Merge branch 'develop' of github.com:secondlife/viewer into roxie/webrtc-voice

11 files changed, 3107 insertions, 711 deletions

diff --git a/indra/newview/gltf/README.md b/indra/newview/gltf/README.md
new file mode 100644
index 0000000000..a2d43be1d6
--- /dev/null
+++ b/indra/newview/gltf/README.md
@@ -0,0 +1,156 @@
+# Linden Lab GLTF Implementation
+
+Currently in prototype stage.  Much functionality is missing (blend shapes,
+multiple texture coordinates, etc).
+
+GLTF Specification can be found here: https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html.
+If this implementation disagrees with the GLTF Specification, the specification is correct.
+
+Class structure and naming should match the GLTF Specification as closely as possible while
+conforming to the LL coding standards.  All code in headers should be contained in the
+LL::GLTF namespace.
+
+The implementation serves both the client and the server.
+
+## Design Principles
+
+- The implementation MUST be capable of round-trip serialization with no data loss beyond F64 to F32 conversions.
+- The implementation MUST use the same indexing scheme as the GLTF specification.  Do not store pointers where the
+- GLTF specification stores indices, store indices.
+- Limit dependencies on llcommon as much as possible.  Prefer std::, boost::, and (soon) glm:: over LL facsimiles.
+- Usage of LLSD is forbidden in the LL::GLTF namespace.
+- Use "using namespace" liberally in .cpp files, but never in .h files.
+- "using Foo = Bar" is permissible in .h files within the LL::GLTF namespace.
+
+## Loading, Copying, and Serialization
+Each class should provide two functions (Primitive shown for example):
+
+```
+// Serialize to the provided json object.
+// "obj" should be "this" in json form on return
+// Do not serialize default values
+void serialize(boost::json::object& obj) const;
+
+// Initialize from a provided json value
+const Primitive& operator=(const Value& src);
+```
+
+"serialize" implementations should use "write":
+
+```
+void Primitive::serialize(boost::json::object& dst) const
+{
+    write(mMaterial, "material", dst, -1);
+    write(mMode, "mode", dst, TINYGLTF_MODE_TRIANGLES);
+    write(mIndices, "indices", dst, INVALID_INDEX);
+    write(mAttributes, "attributes", dst);
+}
+```
+
+And operator= implementations should use "copy":
+
+```
+const Primitive& Primitive::operator=(const Value& src)
+{
+    if (src.is_object())
+    {
+        copy(src, "material", mMaterial);
+        copy(src, "mode", mMode);
+        copy(src, "indices", mIndices);
+        copy(src, "attributes", mAttributes);
+
+        mGLMode = gltf_mode_to_gl_mode(mMode);
+    }
+    return *this;
+}
+```
+
+Parameters to "write" and "copy" MUST be ordered "src" before "dst"
+so the code reads as "write src to dst" and "copy src to dst".
+
+When reading string constants from GLTF json (i.e. "OPAQUE", "TRIANGLES"), these
+strings should be converted to enums inside operator=.  It is permissible to
+store the original strings during prototyping to aid in development, but eventually
+we'll purge these strings from the implementation.  However, implementations MUST
+preserve any and all "name" members.
+
+"write" and "copy" implementations MUST be stored in buffer_util.h.
+As implementers encounter new data types, you'll see compiler errors
+pointing at templates in buffer_util.h.  See vec3 as a known good
+example of how to add support for a new type (there are bad examples, so beware):
+
+```
+// vec3
+template<>
+inline bool copy(const Value& src, vec3& dst)
+{
+    if (src.is_array())
+    {
+        const boost::json::array& arr = src.as_array();
+        if (arr.size() == 3)
+        {
+            if (arr[0].is_double() &&
+                arr[1].is_double() &&
+                arr[2].is_double())
+            {
+                dst = vec3(arr[0].get_double(), arr[1].get_double(), arr[2].get_double());
+            }
+            return true;
+        }
+    }
+    return false;
+}
+
+template<>
+inline bool write(const vec3& src, Value& dst)
+{
+    dst = boost::json::array();
+    boost::json::array& arr = dst.as_array();
+    arr.resize(3);
+    arr[0] = src.x;
+    arr[1] = src.y;
+    arr[2] = src.z;
+    return true;
+}
+
+```
+
+"write" MUST return true if ANY data was written
+"copy" MUST return true if ANY data was copied
+
+Speed is important, but so is safety.  In writers, try to avoid redundant copies
+(prefer resize over push_back, convert dst to an empty array and fill it, don't
+make an array on the stack and copy it into dst).
+
+boost::json WILL throw exceptions if you call as_foo() on a mismatched type but
+WILL NOT throw exceptions on get_foo with a mismatched type.  ALWAYS check is_foo
+before calling as_foo or get_foo.  DO NOT add exception handlers.  If boost throws
+an exception in serialization, the fix is to add type checks.  If we see a large
+number of crash reports from boost::json exceptions, each of those reports
+indicates a place where we're missing "is_foo" checks.  They are gold.  Do not
+bury them with an exception handler.
+
+DO NOT rely on existing type conversion tools in the LL codebase -- LL data models
+conflict with the GLTF specification so we MUST provide conversions independent of
+our existing implementations.
+
+### JSON Serialization ###
+
+
+
+NEVER include buffer_util.h from a header.
+
+Loading from and saving to disk (import/export) is currently done using tinygltf, but this is not a long term
+solution.  Eventually the implementation should rely solely on boost::json for reading and writing .gltf
+files and should handle .bin files natively.
+
+When serializing Images and Buffers to the server, clients MUST store a single UUID "uri" field and nothing else.
+The server MUST reject any data that violates this requirement.
+
+Clients MUST remove any Images from Buffers prior to upload to the server.
+Servers MAY reject Assets that contain Buffers with unreferenced data.
+
+... to be continued.
+
+
+
diff --git a/indra/newview/gltf/accessor.cpp b/indra/newview/gltf/accessor.cpp
index 55d36b7a32..2ef9237f2d 100644
--- a/indra/newview/gltf/accessor.cpp
+++ b/indra/newview/gltf/accessor.cpp
@@ -27,40 +27,272 @@
 #include "../llviewerprecompiledheaders.h"
 
 #include "asset.h"
+#include "buffer_util.h"
+#include "llfilesystem.h"
 
 using namespace LL::GLTF;
+using namespace boost::json;
 
-const Buffer& Buffer::operator=(const tinygltf::Buffer& src)
+namespace LL
 {
-    mData = src.data;
-    mName = src.name;
-    mUri = src.uri;
+    namespace GLTF
+    {
+        Accessor::Type gltf_type_to_enum(const std::string& type)
+        {
+            if (type == "SCALAR")
+            {
+                return Accessor::Type::SCALAR;
+            }
+            else if (type == "VEC2")
+            {
+                return Accessor::Type::VEC2;
+            }
+            else if (type == "VEC3")
+            {
+                return Accessor::Type::VEC3;
+            }
+            else if (type == "VEC4")
+            {
+                return Accessor::Type::VEC4;
+            }
+            else if (type == "MAT2")
+            {
+                return Accessor::Type::MAT2;
+            }
+            else if (type == "MAT3")
+            {
+                return Accessor::Type::MAT3;
+            }
+            else if (type == "MAT4")
+            {
+                return Accessor::Type::MAT4;
+            }
+
+            LL_WARNS("GLTF") << "Unknown accessor type: " << type << LL_ENDL;
+            llassert(false);
+
+            return Accessor::Type::SCALAR;
+        }
+
+        std::string enum_to_gltf_type(Accessor::Type type)
+        {
+            switch (type)
+            {
+            case Accessor::Type::SCALAR:
+                return "SCALAR";
+            case Accessor::Type::VEC2:
+                return "VEC2";
+            case Accessor::Type::VEC3:
+                return "VEC3";
+            case Accessor::Type::VEC4:
+                return "VEC4";
+            case Accessor::Type::MAT2:
+                return "MAT2";
+            case Accessor::Type::MAT3:
+                return "MAT3";
+            case Accessor::Type::MAT4:
+                return "MAT4";
+            }
+
+            LL_WARNS("GLTF") << "Unknown accessor type: " << (S32)type << LL_ENDL;
+            llassert(false);
+
+            return "SCALAR";
+        }
+    }
+}
+
+void Buffer::erase(Asset& asset, S32 offset, S32 length)
+{
+    S32 idx = this - &asset.mBuffers[0];
+
+    mData.erase(mData.begin() + offset, mData.begin() + offset + length);
+
+    llassert(mData.size() <= size_t(INT_MAX));
+    mByteLength = S32(mData.size());
+
+    for (BufferView& view : asset.mBufferViews)
+    {
+        if (view.mBuffer == idx)
+        {
+            if (view.mByteOffset >= offset)
+            {
+                view.mByteOffset -= length;
+            }
+        }
+    }
+}
+
+bool Buffer::prep(Asset& asset)
+{
+    if (mByteLength == 0)
+    {
+        return false;
+    }
+
+    LLUUID id;
+    if (mUri.size() == UUID_STR_SIZE && LLUUID::parseUUID(mUri, &id) && id.notNull())
+    { // loaded from an asset, fetch the buffer data from the asset store
+        LLFileSystem file(id, LLAssetType::AT_GLTF_BIN, LLFileSystem::READ);
+
+        if (mByteLength > file.getSize())
+        {
+            LL_WARNS("GLTF") << "Unexpected glbin size: " << id << " is " << file.getSize() << " bytes, expected " << mByteLength << LL_ENDL;
+            return false;
+        }
+
+        mData.resize(mByteLength);
+        if (!file.read((U8*)mData.data(), mByteLength))
+        {
+            LL_WARNS("GLTF") << "Failed to load buffer data from asset: " << id << LL_ENDL;
+            return false;
+        }
+    }
+    else if (mUri.find("data:") == 0)
+    { // loaded from a data URI, load the texture from the data
+        LL_WARNS() << "Data URIs not yet supported" << LL_ENDL;
+        return false;
+    }
+    else if (!asset.mFilename.empty() &&
+        !mUri.empty()) // <-- uri could be empty if we're loading from .glb
+    {
+        std::string dir = gDirUtilp->getDirName(asset.mFilename);
+        std::string bin_file = dir + gDirUtilp->getDirDelimiter() + mUri;
+
+        std::ifstream file(bin_file, std::ios::binary);
+        if (!file.is_open())
+        {
+            LL_WARNS("GLTF") << "Failed to open file: " << bin_file << LL_ENDL;
+            return false;
+        }
+
+        file.seekg(0, std::ios::end);
+        if (mByteLength > file.tellg())
+        {
+            LL_WARNS("GLTF") << "Unexpected file size: " << bin_file << " is " << file.tellg() << " bytes, expected " << mByteLength << LL_ENDL;
+            return false;
+        }
+        file.seekg(0, std::ios::beg);
+
+        mData.resize(mByteLength);
+        file.read((char*)mData.data(), mData.size());
+    }
+
+    // POSTCONDITION: on success, mData.size == mByteLength
+    llassert(mData.size() == mByteLength);
+    return true;
+}
+
+bool Buffer::save(Asset& asset, const std::string& folder)
+{
+    if (mUri.substr(0, 5) == "data:")
+    {
+        LL_WARNS("GLTF") << "Data URIs not yet supported" << LL_ENDL;
+        return false;
+    }
+
+    std::string bin_file = folder + gDirUtilp->getDirDelimiter();
+
+    if (mUri.empty())
+    {
+        if (mName.empty())
+        {
+            S32 idx = this - &asset.mBuffers[0];
+            mUri = llformat("buffer_%d.bin", idx);
+        }
+        else
+        {
+            mUri = mName + ".bin";
+        }
+    }
+
+    bin_file += mUri;
+
+    std::ofstream file(bin_file, std::ios::binary);
+    if (!file.is_open())
+    {
+        LL_WARNS("GLTF") << "Failed to open file: " << bin_file << LL_ENDL;
+        return false;
+    }
+
+    file.write((char*)mData.data(), mData.size());
+
+    return true;
+}
+
+void Buffer::serialize(object& dst) const
+{
+    write(mName, "name", dst);
+    write(mUri, "uri", dst);
+    write_always(mByteLength, "byteLength", dst);
+};
+
+const Buffer& Buffer::operator=(const Value& src)
+{
+    if (src.is_object())
+    {
+        copy(src, "name", mName);
+        copy(src, "uri", mUri);
+        copy(src, "byteLength", mByteLength);
+
+        // NOTE: DO NOT attempt to handle the uri here.
+        // The uri is a reference to a file that is not loaded until
+        // after the json document is parsed
+    }
     return *this;
 }
 
-const BufferView& BufferView::operator=(const tinygltf::BufferView& src)
+void BufferView::serialize(object& dst) const
 {
-    mBuffer = src.buffer;
-    mByteLength = src.byteLength;
-    mByteOffset = src.byteOffset;
-    mByteStride = src.byteStride;
-    mTarget = src.target;
-    mName = src.name;
+    write_always(mBuffer, "buffer", dst);
+    write_always(mByteLength, "byteLength", dst);
+    write(mByteOffset, "byteOffset", dst, 0);
+    write(mByteStride, "byteStride", dst, 0);
+    write(mTarget, "target", dst, -1);
+    write(mName, "name", dst);
+}
+
+const BufferView& BufferView::operator=(const Value& src)
+{
+    if (src.is_object())
+    {
+        copy(src, "buffer", mBuffer);
+        copy(src, "byteLength", mByteLength);
+        copy(src, "byteOffset", mByteOffset);
+        copy(src, "byteStride", mByteStride);
+        copy(src, "target", mTarget);
+        copy(src, "name", mName);
+    }
     return *this;
 }
 
-const Accessor& Accessor::operator=(const tinygltf::Accessor& src)
+void Accessor::serialize(object& dst) const
 {
-    mBufferView = src.bufferView;
-    mByteOffset = src.byteOffset;
-    mComponentType = src.componentType;
-    mCount = src.count;
-    mType = src.type;
-    mNormalized = src.normalized;
-    mName = src.name;
-    mMax = src.maxValues;
-    mMin = src.minValues;
+    write(mName, "name", dst);
+    write(mBufferView, "bufferView", dst, INVALID_INDEX);
+    write(mByteOffset, "byteOffset", dst, 0);
+    write_always(mComponentType, "componentType", dst);
+    write_always(mCount, "count", dst);
+    write_always(enum_to_gltf_type(mType), "type", dst);
+    write(mNormalized, "normalized", dst, false);
+    write(mMax, "max", dst);
+    write(mMin, "min", dst);
+}
 
+const Accessor& Accessor::operator=(const Value& src)
+{
+    if (src.is_object())
+    {
+        copy(src, "name", mName);
+        copy(src, "bufferView", mBufferView);
+        copy(src, "byteOffset", mByteOffset);
+        copy(src, "componentType", mComponentType);
+        copy(src, "count", mCount);
+        copy(src, "type", mType);
+        copy(src, "normalized", mNormalized);
+        copy(src, "max", mMax);
+        copy(src, "min", mMin);
+    }
     return *this;
 }
 
diff --git a/indra/newview/gltf/accessor.h b/indra/newview/gltf/accessor.h
index 9b8265d8da..ec68c5f624 100644
--- a/indra/newview/gltf/accessor.h
+++ b/indra/newview/gltf/accessor.h
@@ -26,16 +26,16 @@
  * $/LicenseInfo$
  */
 
-#include "../lltinygltfhelper.h"
 #include "llstrider.h"
+#include "boost/json.hpp"
+
+#include "common.h"
 
 // LL GLTF Implementation
 namespace LL
 {
     namespace GLTF
     {
-        class Asset;
-
         constexpr S32 INVALID_INDEX = -1;
 
         class Buffer
@@ -44,52 +44,77 @@ namespace LL
             std::vector<U8> mData;
             std::string mName;
             std::string mUri;
+            S32 mByteLength = 0;
+
+            // erase the given range from this buffer.
+            // also updates all buffer views in given asset that reference this buffer
+            void erase(Asset& asset, S32 offset, S32 length);
+
+            bool prep(Asset& asset);
 
-            const Buffer& operator=(const tinygltf::Buffer& src);
+            void serialize(boost::json::object& obj) const;
+            const Buffer& operator=(const Value& value);
+
+            bool save(Asset& asset, const std::string& folder);
         };
 
         class BufferView
         {
         public:
             S32 mBuffer = INVALID_INDEX;
-            S32 mByteLength;
-            S32 mByteOffset;
-            S32 mByteStride;
-            S32 mTarget;
-            S32 mComponentType;
+            S32 mByteLength = 0;
+            S32 mByteOffset = 0;
+            S32 mByteStride = 0;
+            S32 mTarget = -1;
 
             std::string mName;
 
-            const BufferView& operator=(const tinygltf::BufferView& src);
-            
+            void serialize(boost::json::object& obj) const;
+            const BufferView& operator=(const Value& value);
         };
-        
+
         class Accessor
         {
         public:
-            S32 mBufferView = INVALID_INDEX;
-            S32 mByteOffset;
-            S32 mComponentType;
-            S32 mCount;
-            std::vector<double> mMax;
-            std::vector<double> mMin;
+            enum class Type : U8
+            {
+                SCALAR,
+                VEC2,
+                VEC3,
+                VEC4,
+                MAT2,
+                MAT3,
+                MAT4
+            };
 
-            enum class Type : S32
+            enum class ComponentType : U32
             {
-                SCALAR = TINYGLTF_TYPE_SCALAR,
-                VEC2 = TINYGLTF_TYPE_VEC2,
-                VEC3 = TINYGLTF_TYPE_VEC3,
-                VEC4 = TINYGLTF_TYPE_VEC4,
-                MAT2 = TINYGLTF_TYPE_MAT2,
-                MAT3 = TINYGLTF_TYPE_MAT3,
-                MAT4 = TINYGLTF_TYPE_MAT4
+                BYTE = 5120,
+                UNSIGNED_BYTE = 5121,
+                SHORT = 5122,
+                UNSIGNED_SHORT = 5123,
+                UNSIGNED_INT = 5125,
+                FLOAT = 5126
             };
 
-            S32 mType;
-            bool mNormalized;
+            std::vector<double> mMax;
+            std::vector<double> mMin;
             std::string mName;
+            S32 mBufferView = INVALID_INDEX;
+            S32 mByteOffset = 0;
+            ComponentType mComponentType = ComponentType::BYTE;
+            S32 mCount = 0;
+            Type mType = Type::SCALAR;
+            bool mNormalized = false;
 
-            const Accessor& operator=(const tinygltf::Accessor& src);
+            void serialize(boost::json::object& obj) const;
+            const Accessor& operator=(const Value& value);
         };
+
+        // convert from "SCALAR", "VEC2", etc to Accessor::Type
+        Accessor::Type gltf_type_to_enum(const std::string& type);
+
+        // convert from Accessor::Type to "SCALAR", "VEC2", etc
+        std::string enum_to_gltf_type(Accessor::Type type);
     }
 }
diff --git a/indra/newview/gltf/animation.cpp b/indra/newview/gltf/animation.cpp
index da6d02b356..8b85eba3e5 100644
--- a/indra/newview/gltf/animation.cpp
+++ b/indra/newview/gltf/animation.cpp
@@ -28,10 +28,12 @@
 
 #include "asset.h"
 #include "buffer_util.h"
+#include "../llskinningutil.h"
 
 using namespace LL::GLTF;
+using namespace boost::json;
 
-void Animation::allocateGLResources(Asset& asset)
+bool Animation::prep(Asset& asset)
 {
     if (!mSamplers.empty())
     {
@@ -39,7 +41,10 @@ void Animation::allocateGLResources(Asset& asset)
         mMaxTime = -FLT_MAX;
         for (auto& sampler : mSamplers)
         {
-            sampler.allocateGLResources(asset);
+            if (!sampler.prep(asset))
+            {
+                return false;
+            }
             mMinTime = llmin(sampler.mMinTime, mMinTime);
             mMaxTime = llmax(sampler.mMaxTime, mMaxTime);
         }
@@ -51,13 +56,21 @@ void Animation::allocateGLResources(Asset& asset)
 
     for (auto& channel : mRotationChannels)
     {
-        channel.allocateGLResources(asset, mSamplers[channel.mSampler]);
+        if (!channel.prep(asset, mSamplers[channel.mSampler]))
+        {
+            return false;
+        }
     }
 
     for (auto& channel : mTranslationChannels)
     {
-        channel.allocateGLResources(asset, mSamplers[channel.mSampler]);
+        if (!channel.prep(asset, mSamplers[channel.mSampler]))
+        {
+            return false;
+        }
     }
+
+    return true;
 }
 
 void Animation::update(Asset& asset, F32 dt)
@@ -84,8 +97,7 @@ void Animation::apply(Asset& asset, float time)
     }
 };
 
-
-void Animation::Sampler::allocateGLResources(Asset& asset)
+bool Animation::Sampler::prep(Asset& asset)
 {
     Accessor& accessor = asset.mAccessors[mInput];
     mMinTime = accessor.mMin[0];
@@ -95,10 +107,79 @@ void Animation::Sampler::allocateGLResources(Asset& asset)
 
     LLStrider<F32> frame_times = mFrameTimes.data();
     copy(asset, accessor, frame_times);
+
+    return true;
+}
+
+
+void Animation::Sampler::serialize(object& obj) const
+{
+    write(mInput, "input", obj, INVALID_INDEX);
+    write(mOutput, "output", obj, INVALID_INDEX);
+    write(mInterpolation, "interpolation", obj, std::string("LINEAR"));
+    write(mMinTime, "min_time", obj);
+    write(mMaxTime, "max_time", obj);
+}
+
+const Animation::Sampler& Animation::Sampler::operator=(const Value& src)
+{
+    if (src.is_object())
+    {
+        copy(src, "input", mInput);
+        copy(src, "output", mOutput);
+        copy(src, "interpolation", mInterpolation);
+        copy(src, "min_time", mMinTime);
+        copy(src, "max_time", mMaxTime);
+    }
+    return *this;
+}
+
+bool Animation::Channel::Target::operator==(const Channel::Target& rhs) const
+{
+    return mNode == rhs.mNode && mPath == rhs.mPath;
+}
+
+bool Animation::Channel::Target::operator!=(const Channel::Target& rhs) const
+{
+    return !(*this == rhs);
+}
+
+void Animation::Channel::Target::serialize(object& obj) const
+{
+    write(mNode, "node", obj, INVALID_INDEX);
+    write(mPath, "path", obj);
+}
+
+const Animation::Channel::Target& Animation::Channel::Target::operator=(const Value& src)
+{
+    if (src.is_object())
+    {
+        copy(src, "node", mNode);
+        copy(src, "path", mPath);
+    }
+    return *this;
+}
+
+void Animation::Channel::serialize(object& obj) const
+{
+    write(mSampler, "sampler", obj, INVALID_INDEX);
+    write(mTarget, "target", obj);
+}
+
+const Animation::Channel& Animation::Channel::operator=(const Value& src)
+{
+    if (src.is_object())
+    {
+        copy(src, "sampler", mSampler);
+        copy(src, "target", mTarget);
+    }
+    return *this;
 }
 
 void Animation::Sampler::getFrameInfo(Asset& asset, F32 time, U32& frameIndex, F32& t)
 {
+    LL_PROFILE_ZONE_SCOPED;
+
     if (time < mMinTime)
     {
         frameIndex = 0;
@@ -108,17 +189,16 @@ void Animation::Sampler::getFrameInfo(Asset& asset, F32 time, U32& frameIndex, F
 
     if (mFrameTimes.size() > 1)
     {
+        llassert(mFrameTimes.size() <= size_t(U32_MAX));
+        frameIndex = U32(mFrameTimes.size()) - 2;
+        t = 1.f;
+
         if (time > mMaxTime)
         {
-            frameIndex = mFrameTimes.size() - 2;
-            t = 1.0f;
             return;
         }
 
-        frameIndex = mFrameTimes.size() - 2;
-        t = 1.f;
-
-        for (U32 i = 0; i < mFrameTimes.size() - 1; i++)
+        for (U32 i = 0; i < (U32)mFrameTimes.size() - 1; i++)
         {
             if (time >= mFrameTimes[i] && time < mFrameTimes[i + 1])
             {
@@ -135,11 +215,13 @@ void Animation::Sampler::getFrameInfo(Asset& asset, F32 time, U32& frameIndex, F
     }
 }
 
-void Animation::RotationChannel::allocateGLResources(Asset& asset, Animation::Sampler& sampler)
+bool Animation::RotationChannel::prep(Asset& asset, Animation::Sampler& sampler)
 {
     Accessor& accessor = asset.mAccessors[sampler.mOutput];
 
     copy(asset, accessor, mRotations);
+
+    return true;
 }
 
 void Animation::RotationChannel::apply(Asset& asset, Sampler& sampler, F32 time)
@@ -158,21 +240,21 @@ void Animation::RotationChannel::apply(Asset& asset, Sampler& sampler, F32 time)
     else
     {
         // interpolate
-        LLQuaternion q0(mRotations[frameIndex].get_value());
-        LLQuaternion q1(mRotations[frameIndex + 1].get_value());
+        quat qf = glm::slerp(mRotations[frameIndex], mRotations[frameIndex + 1], t);
 
-        LLQuaternion qf = slerp(t, q0, q1);
+        qf = glm::normalize(qf);
 
-        qf.normalize();
-        node.setRotation(glh::quaternionf(qf.mQ));
+        node.setRotation(qf);
     }
 }
 
-void Animation::TranslationChannel::allocateGLResources(Asset& asset, Animation::Sampler& sampler)
+bool Animation::TranslationChannel::prep(Asset& asset, Animation::Sampler& sampler)
 {
     Accessor& accessor = asset.mAccessors[sampler.mOutput];
 
     copy(asset, accessor, mTranslations);
+
+    return true;
 }
 
 void Animation::TranslationChannel::apply(Asset& asset, Sampler& sampler, F32 time)
@@ -191,20 +273,22 @@ void Animation::TranslationChannel::apply(Asset& asset, Sampler& sampler, F32 ti
     else
     {
         // interpolate
-        const glh::vec3f& v0 = mTranslations[frameIndex];
-        const glh::vec3f& v1 = mTranslations[frameIndex + 1];
+        const vec3& v0 = mTranslations[frameIndex];
+        const vec3& v1 = mTranslations[frameIndex + 1];
 
-        glh::vec3f vf = v0 + t * (v1 - v0);
+        vec3 vf = v0 + t * (v1 - v0);
 
         node.setTranslation(vf);
     }
 }
 
-void Animation::ScaleChannel::allocateGLResources(Asset& asset, Animation::Sampler& sampler)
+bool Animation::ScaleChannel::prep(Asset& asset, Animation::Sampler& sampler)
 {
     Accessor& accessor = asset.mAccessors[sampler.mOutput];
 
     copy(asset, accessor, mScales);
+
+    return true;
 }
 
 void Animation::ScaleChannel::apply(Asset& asset, Sampler& sampler, F32 time)
@@ -223,65 +307,153 @@ void Animation::ScaleChannel::apply(Asset& asset, Sampler& sampler, F32 time)
     else
     {
         // interpolate
-        const glh::vec3f& v0 = mScales[frameIndex];
-        const glh::vec3f& v1 = mScales[frameIndex + 1];
+        const vec3& v0 = mScales[frameIndex];
+        const vec3& v1 = mScales[frameIndex + 1];
 
-        glh::vec3f vf = v0 + t * (v1 - v0);
+        vec3 vf = v0 + t * (v1 - v0);
 
         node.setScale(vf);
     }
 }
 
-const Animation& Animation::operator=(const tinygltf::Animation& src)
+void Animation::serialize(object& obj) const
 {
-    mName = src.name;
+    write(mName, "name", obj);
+    write(mSamplers, "samplers", obj);
 
-    mSamplers.resize(src.samplers.size());
-    for (U32 i = 0; i < src.samplers.size(); ++i)
-    {
-        mSamplers[i] = src.samplers[i];
-    }
+    std::vector<Channel> channels;
+    channels.insert(channels.end(), mRotationChannels.begin(), mRotationChannels.end());
+    channels.insert(channels.end(), mTranslationChannels.begin(), mTranslationChannels.end());
+    channels.insert(channels.end(), mScaleChannels.begin(), mScaleChannels.end());
+
+    write(channels, "channels", obj);
+}
 
-    for (U32 i = 0; i < src.channels.size(); ++i)
+const Animation& Animation::operator=(const Value& src)
+{
+    if (src.is_object())
     {
-        if (src.channels[i].target_path == "rotation")
-        {
-            mRotationChannels.push_back(RotationChannel());
-            mRotationChannels.back() = src.channels[i];
-        }
+        const object& obj = src.as_object();
 
-        if (src.channels[i].target_path == "translation")
-        {
-            mTranslationChannels.push_back(TranslationChannel());
-            mTranslationChannels.back() = src.channels[i];
-        }
+        copy(obj, "name", mName);
+        copy(obj, "samplers", mSamplers);
+
+        // make a temporory copy of generic channels
+        std::vector<Channel> channels;
+        copy(obj, "channels", channels);
 
-        if (src.channels[i].target_path == "scale")
+        // break up into channel specific implementations
+        for (auto& channel: channels)
         {
-            mScaleChannels.push_back(ScaleChannel());
-            mScaleChannels.back() = src.channels[i];
+            if (channel.mTarget.mPath == "rotation")
+            {
+                mRotationChannels.push_back(channel);
+            }
+            else if (channel.mTarget.mPath == "translation")
+            {
+                mTranslationChannels.push_back(channel);
+            }
+            else if (channel.mTarget.mPath == "scale")
+            {
+                mScaleChannels.push_back(channel);
+            }
         }
     }
-
     return *this;
 }
 
-void Skin::allocateGLResources(Asset& asset)
+Skin::~Skin()
+{
+    if (mUBO)
+    {
+        glDeleteBuffers(1, &mUBO);
+    }
+}
+
+void Skin::uploadMatrixPalette(Asset& asset)
+{
+    // prepare matrix palette
+
+    U32 max_joints = LLSkinningUtil::getMaxGLTFJointCount();
+
+    if (mUBO == 0)
+    {
+        glGenBuffers(1, &mUBO);
+    }
+
+    size_t joint_count = llmin<size_t>(max_joints, mJoints.size());
+
+    std::vector<mat4> t_mp;
+
+    t_mp.resize(joint_count);
+
+    for (U32 i = 0; i < joint_count; ++i)
+    {
+        Node& joint = asset.mNodes[mJoints[i]];
+        // build matrix palette in asset space
+        t_mp[i] = joint.mAssetMatrix * mInverseBindMatricesData[i];
+    }
+
+    std::vector<F32> glmp;
+
+    glmp.resize(joint_count * 12);
+
+    F32* mp = glmp.data();
+
+    for (U32 i = 0; i < joint_count; ++i)
+    {
+        F32* m = glm::value_ptr(t_mp[i]);
+
+        U32 idx = i * 12;
+
+        mp[idx + 0] = m[0];
+        mp[idx + 1] = m[1];
+        mp[idx + 2] = m[2];
+        mp[idx + 3] = m[12];
+
+        mp[idx + 4] = m[4];
+        mp[idx + 5] = m[5];
+        mp[idx + 6] = m[6];
+        mp[idx + 7] = m[13];
+
+        mp[idx + 8] = m[8];
+        mp[idx + 9] = m[9];
+        mp[idx + 10] = m[10];
+        mp[idx + 11] = m[14];
+    }
+
+    glBindBuffer(GL_UNIFORM_BUFFER, mUBO);
+    glBufferData(GL_UNIFORM_BUFFER, glmp.size() * sizeof(F32), glmp.data(), GL_STREAM_DRAW);
+    glBindBuffer(GL_UNIFORM_BUFFER, 0);
+}
+
+bool Skin::prep(Asset& asset)
 {
     if (mInverseBindMatrices != INVALID_INDEX)
     {
         Accessor& accessor = asset.mAccessors[mInverseBindMatrices];
         copy(asset, accessor, mInverseBindMatricesData);
     }
+
+    return true;
 }
 
-const Skin& Skin::operator=(const tinygltf::Skin& src)
+const Skin& Skin::operator=(const Value& src)
 {
-    mName = src.name;
-    mSkeleton = src.skeleton;
-    mInverseBindMatrices = src.inverseBindMatrices;
-    mJoints = src.joints;
-
+    if (src.is_object())
+    {
+        copy(src, "name", mName);
+        copy(src, "skeleton", mSkeleton);
+        copy(src, "inverseBindMatrices", mInverseBindMatrices);
+        copy(src, "joints", mJoints);
+    }
     return *this;
 }
 
+void Skin::serialize(object& obj) const
+{
+    write(mInverseBindMatrices, "inverseBindMatrices", obj, INVALID_INDEX);
+    write(mJoints, "joints", obj);
+    write(mName, "name", obj);
+    write(mSkeleton, "skeleton", obj, INVALID_INDEX);
+}
diff --git a/indra/newview/gltf/animation.h b/indra/newview/gltf/animation.h
index 869eae963a..d5426fd4ce 100644
--- a/indra/newview/gltf/animation.h
+++ b/indra/newview/gltf/animation.h
@@ -27,7 +27,6 @@
  */
 
 #include "accessor.h"
-
 // LL GLTF Implementation
 namespace LL
 {
@@ -50,16 +49,10 @@ namespace LL
                 S32 mOutput = INVALID_INDEX;
                 std::string mInterpolation;
 
-                void allocateGLResources(Asset& asset);
-
-                const Sampler& operator=(const tinygltf::AnimationSampler& src)
-                {
-                    mInput = src.input;
-                    mOutput = src.output;
-                    mInterpolation = src.interpolation;
+                bool prep(Asset& asset);
 
-                    return *this;
-                }
+                void serialize(boost::json::object& dst) const;
+                const Sampler& operator=(const Value& value);
 
                 // get the frame index and time for the specified time
                 // asset -- the asset to reference for Accessors
@@ -77,40 +70,33 @@ namespace LL
                 public:
                     S32 mNode = INVALID_INDEX;
                     std::string mPath;
+
+                    bool operator==(const Target& other) const;
+                    bool operator!=(const Target& other) const;
+
+                    void serialize(boost::json::object& dst) const;
+                    const Target& operator=(const Value& value);
                 };
 
                 S32 mSampler = INVALID_INDEX;
                 Target mTarget;
-                std::string mTargetPath;
-                std::string mName;
-
-                const Channel& operator=(const tinygltf::AnimationChannel& src)
-                {
-                    mSampler = src.sampler;
-
-                    mTarget.mNode = src.target_node;
-                    mTarget.mPath = src.target_path;
-
-                    return *this;
-                }
 
+                void serialize(boost::json::object& dst) const;
+                const Channel& operator=(const Value& value);
             };
 
             class RotationChannel : public Channel
             {
             public:
-                std::vector<glh::quaternionf> mRotations;
+                RotationChannel() = default;
+                RotationChannel(const Channel& channel) : Channel(channel) {}
 
-                const RotationChannel& operator=(const tinygltf::AnimationChannel& src)
-                {
-                    Channel::operator=(src);
-                    return *this;
-                }
+                std::vector<quat> mRotations;
 
                 // prepare data needed for rendering
                 // asset -- asset to reference for Accessors
                 // sampler -- Sampler associated with this channel
-                void allocateGLResources(Asset& asset, Sampler& sampler);
+                bool prep(Asset& asset, Sampler& sampler);
 
                 void apply(Asset& asset, Sampler& sampler, F32 time);
             };
@@ -118,18 +104,15 @@ namespace LL
             class TranslationChannel : public Channel
             {
             public:
-                std::vector<glh::vec3f> mTranslations;
+                TranslationChannel() = default;
+                TranslationChannel(const Channel& channel) : Channel(channel) {}
 
-                const TranslationChannel& operator=(const tinygltf::AnimationChannel& src)
-                {
-                    Channel::operator=(src);
-                    return *this;
-                }
+                std::vector<vec3> mTranslations;
 
                 // prepare data needed for rendering
                 // asset -- asset to reference for Accessors
                 // sampler -- Sampler associated with this channel
-                void allocateGLResources(Asset& asset, Sampler& sampler);
+                bool prep(Asset& asset, Sampler& sampler);
 
                 void apply(Asset& asset, Sampler& sampler, F32 time);
             };
@@ -137,18 +120,15 @@ namespace LL
             class ScaleChannel : public Channel
             {
             public:
-                std::vector<glh::vec3f> mScales;
+                ScaleChannel() = default;
+                ScaleChannel(const Channel& channel) : Channel(channel) {}
 
-                const ScaleChannel& operator=(const tinygltf::AnimationChannel& src)
-                {
-                    Channel::operator=(src);
-                    return *this;
-                }
+                std::vector<vec3> mScales;
 
                 // prepare data needed for rendering
                 // asset -- asset to reference for Accessors
                 // sampler -- Sampler associated with this channel
-                void allocateGLResources(Asset& asset, Sampler& sampler);
+                bool prep(Asset& asset, Sampler& sampler);
 
                 void apply(Asset& asset, Sampler& sampler, F32 time);
             };
@@ -159,7 +139,7 @@ namespace LL
             // min/max time values for all samplers combined
             F32 mMinTime = 0.f;
             F32 mMaxTime = 0.f;
-            
+
             // current time of the animation
             F32 mTime = 0.f;
 
@@ -167,9 +147,10 @@ namespace LL
             std::vector<TranslationChannel> mTranslationChannels;
             std::vector<ScaleChannel> mScaleChannels;
 
-            const Animation& operator=(const tinygltf::Animation& src);
-            
-            void allocateGLResources(Asset& asset);
+            void serialize(boost::json::object& dst) const;
+            const Animation& operator=(const Value& value);
+
+            bool prep(Asset& asset);
 
             void update(Asset& asset, float dt);
 
diff --git a/indra/newview/gltf/asset.cpp b/indra/newview/gltf/asset.cpp
index 313e82bf01..21be69aae2 100644
--- a/indra/newview/gltf/asset.cpp
+++ b/indra/newview/gltf/asset.cpp
@@ -30,13 +30,67 @@
 #include "llvolumeoctree.h"
 #include "../llviewershadermgr.h"
 #include "../llviewercontrol.h"
+#include "../llviewertexturelist.h"
+#include "../pipeline.h"
+#include "buffer_util.h"
+#include <boost/url.hpp>
+#include "llimagejpeg.h"
 
 using namespace LL::GLTF;
+using namespace boost::json;
+
+
+namespace LL
+{
+    namespace GLTF
+    {
+        static std::unordered_set<std::string> ExtensionsSupported = {
+            "KHR_materials_unlit",
+            "KHR_texture_transform"
+        };
+
+        Material::AlphaMode gltf_alpha_mode_to_enum(const std::string& alpha_mode)
+        {
+            if (alpha_mode == "OPAQUE")
+            {
+                return Material::AlphaMode::OPAQUE;
+            }
+            else if (alpha_mode == "MASK")
+            {
+                return Material::AlphaMode::MASK;
+            }
+            else if (alpha_mode == "BLEND")
+            {
+                return Material::AlphaMode::BLEND;
+            }
+            else
+            {
+                return Material::AlphaMode::OPAQUE;
+            }
+        }
+
+        std::string enum_to_gltf_alpha_mode(Material::AlphaMode alpha_mode)
+        {
+            switch (alpha_mode)
+            {
+            case Material::AlphaMode::OPAQUE:
+                return "OPAQUE";
+            case Material::AlphaMode::MASK:
+                return "MASK";
+            case Material::AlphaMode::BLEND:
+                return "BLEND";
+            default:
+                return "OPAQUE";
+            }
+        }
+    }
+}
+
 
 void Scene::updateTransforms(Asset& asset)
 {
-    LLMatrix4a identity;
-    identity.setIdentity();
+    mat4 identity = glm::identity<mat4>();
+
     for (auto& nodeIndex : mNodes)
     {
         Node& node = asset.mNodes[nodeIndex];
@@ -44,7 +98,7 @@ void Scene::updateTransforms(Asset& asset)
     }
 }
 
-void Scene::updateRenderTransforms(Asset& asset, const LLMatrix4a& modelview)
+void Scene::updateRenderTransforms(Asset& asset, const mat4& modelview)
 {
     for (auto& nodeIndex : mNodes)
     {
@@ -53,9 +107,9 @@ void Scene::updateRenderTransforms(Asset& asset, const LLMatrix4a& modelview)
     }
 }
 
-void Node::updateRenderTransforms(Asset& asset, const LLMatrix4a& modelview)
+void Node::updateRenderTransforms(Asset& asset, const mat4& modelview)
 {
-    matMul(mMatrix, modelview, mRenderMatrix);
+    mRenderMatrix = modelview * mMatrix;
 
     for (auto& childIndex : mChildren)
     {
@@ -64,14 +118,13 @@ void Node::updateRenderTransforms(Asset& asset, const LLMatrix4a& modelview)
     }
 }
 
-LLMatrix4a inverse(const LLMatrix4a& mat);
-
-void Node::updateTransforms(Asset& asset, const LLMatrix4a& parentMatrix)
+void Node::updateTransforms(Asset& asset, const mat4& parentMatrix)
 {
     makeMatrixValid();
-    matMul(mMatrix, parentMatrix, mAssetMatrix);
-    mAssetMatrixInv = inverse(mAssetMatrix);
-    
+    mAssetMatrix = parentMatrix * mMatrix;
+
+    mAssetMatrixInv = glm::inverse(mAssetMatrix);
+
     S32 my_index = this - &asset.mNodes[0];
 
     for (auto& childIndex : mChildren)
@@ -90,26 +143,13 @@ void Asset::updateTransforms()
     }
 }
 
-void Asset::updateRenderTransforms(const LLMatrix4a& modelview)
+void Asset::updateRenderTransforms(const mat4& modelview)
 {
-#if 0
-    // traverse hierarchy and update render transforms from scratch
-    for (auto& scene : mScenes)
-    {
-        scene.updateRenderTransforms(*this, modelview);
-    }
-#else
     // use mAssetMatrix to update render transforms from node list
     for (auto& node : mNodes)
     {
-        //if (node.mMesh != INVALID_INDEX)
-        {
-            matMul(node.mAssetMatrix, modelview, node.mRenderMatrix);
-        }
+        node.mRenderMatrix = modelview * node.mAssetMatrix;
     }
-
-#endif
-
 }
 
 S32 Asset::lineSegmentIntersect(const LLVector4a& start, const LLVector4a& end,
@@ -133,12 +173,13 @@ S32 Asset::lineSegmentIntersect(const LLVector4a& start, const LLVector4a& end,
     {
         if (node.mMesh != INVALID_INDEX)
         {
-            
             bool newHit = false;
 
+            LLMatrix4a ami;
+            ami.loadu(glm::value_ptr(node.mAssetMatrixInv));
             // transform start and end to this node's local space
-            node.mAssetMatrixInv.affineTransform(start, local_start);
-            node.mAssetMatrixInv.affineTransform(asset_end, local_end);
+            ami.affineTransform(start, local_start);
+            ami.affineTransform(asset_end, local_end);
 
             Mesh& mesh = mMeshes[node.mMesh];
             for (auto& primitive : mesh.mPrimitives)
@@ -161,8 +202,10 @@ S32 Asset::lineSegmentIntersect(const LLVector4a& start, const LLVector4a& end,
 
             if (newHit)
             {
+                LLMatrix4a am;
+                am.loadu(glm::value_ptr(node.mAssetMatrix));
                 // shorten line segment on hit
-                node.mAssetMatrix.affineTransform(p, asset_end); 
+                am.affineTransform(p, asset_end);
 
                 // transform results back to asset space
                 if (intersection)
@@ -172,12 +215,10 @@ S32 Asset::lineSegmentIntersect(const LLVector4a& start, const LLVector4a& end,
 
                 if (normal || tangent)
                 {
-                    LLMatrix4 normalMatrix(node.mAssetMatrixInv.getF32ptr());
-
-                    normalMatrix.transpose();
+                    mat4 normalMatrix = glm::transpose(node.mAssetMatrixInv);
 
                     LLMatrix4a norm_mat;
-                    norm_mat.loadu((F32*)normalMatrix.mMatrix);
+                    norm_mat.loadu(glm::value_ptr(normalMatrix));
 
                     if (normal)
                     {
@@ -219,446 +260,933 @@ void Node::makeMatrixValid()
 {
     if (!mMatrixValid && mTRSValid)
     {
-        glh::matrix4f rot;
-        mRotation.get_value(rot);
-
-        glh::matrix4f trans;
-        trans.set_translate(mTranslation);
-
-        glh::matrix4f sc;
-        sc.set_scale(mScale);
-
-        glh::matrix4f t;
-        //t = sc * rot * trans; 
-        //t = trans * rot * sc; // best so far, still wrong on negative scale
-        //t = sc * trans * rot;
-        t = trans * sc * rot;
-
-        mMatrix.loadu(t.m);
+        mMatrix = glm::recompose(mScale, mRotation, mTranslation, vec3(0,0,0), vec4(0,0,0,1));
         mMatrixValid = true;
     }
+
+    llassert(mMatrixValid);
 }
 
 void Node::makeTRSValid()
 {
     if (!mTRSValid && mMatrixValid)
     {
-        glh::matrix4f t(mMatrix.getF32ptr());
-
-        glh::vec4f p = t.get_column(3);
-        mTranslation.set_value(p.v[0], p.v[1], p.v[2]);
+        vec3 skew;
+        vec4 perspective;
+        glm::decompose(mMatrix, mScale, mRotation, mTranslation, skew, perspective);
 
-        mScale.set_value(t.get_column(0).length(), t.get_column(1).length(), t.get_column(2).length());
-        mRotation.set_value(t);
         mTRSValid = true;
     }
+
+    llassert(mTRSValid);
 }
 
-void Node::setRotation(const glh::quaternionf& q)
+void Node::setRotation(const quat& q)
 {
     makeTRSValid();
     mRotation = q;
     mMatrixValid = false;
 }
 
-void Node::setTranslation(const glh::vec3f& t)
+void Node::setTranslation(const vec3& t)
 {
     makeTRSValid();
     mTranslation = t;
     mMatrixValid = false;
 }
 
-void Node::setScale(const glh::vec3f& s)
+void Node::setScale(const vec3& s)
 {
     makeTRSValid();
     mScale = s;
     mMatrixValid = false;
 }
 
-const Node& Node::operator=(const tinygltf::Node& src)
+void Node::serialize(object& dst) const
 {
-    F32* dstMatrix = mMatrix.getF32ptr();
+    write(mName, "name", dst);
+    write(mMatrix, "matrix", dst, glm::identity<mat4>());
+    write(mRotation, "rotation", dst, glm::identity<quat>());
+    write(mTranslation, "translation", dst, glm::vec3(0.f, 0.f, 0.f));
+    write(mScale, "scale", dst, vec3(1.f,1.f,1.f));
+    write(mChildren, "children", dst);
+    write(mMesh, "mesh", dst, INVALID_INDEX);
+    write(mSkin, "skin", dst, INVALID_INDEX);
+}
 
-    if (src.matrix.size() == 16)
+const Node& Node::operator=(const Value& src)
+{
+    copy(src, "name", mName);
+    mMatrixValid = copy(src, "matrix", mMatrix);
+    copy(src, "rotation", mRotation);
+    copy(src, "translation", mTranslation);
+    copy(src, "scale", mScale);
+    copy(src, "children", mChildren);
+    copy(src, "mesh", mMesh);
+    copy(src, "skin", mSkin);
+
+    if (!mMatrixValid)
     {
-        // Node has a transformation matrix, just copy it
-        for (U32 i = 0; i < 16; ++i)
+        mTRSValid = true;
+    }
+
+    return *this;
+}
+
+void Image::serialize(object& dst) const
+{
+    write(mUri, "uri", dst);
+    write(mMimeType, "mimeType", dst);
+    write(mBufferView, "bufferView", dst, INVALID_INDEX);
+    write(mName, "name", dst);
+    write(mWidth, "width", dst, -1);
+    write(mHeight, "height", dst, -1);
+    write(mComponent, "component", dst, -1);
+    write(mBits, "bits", dst, -1);
+    write(mPixelType, "pixelType", dst, -1);
+}
+
+const Image& Image::operator=(const Value& src)
+{
+    copy(src, "uri", mUri);
+    copy(src, "mimeType", mMimeType);
+    copy(src, "bufferView", mBufferView);
+    copy(src, "name", mName);
+    copy(src, "width", mWidth);
+    copy(src, "height", mHeight);
+    copy(src, "component", mComponent);
+    copy(src, "bits", mBits);
+    copy(src, "pixelType", mPixelType);
+
+    return *this;
+}
+
+void Asset::update()
+{
+    F32 dt = gFrameTimeSeconds - mLastUpdateTime;
+
+    if (dt > 0.f)
+    {
+        mLastUpdateTime = gFrameTimeSeconds;
+        if (mAnimations.size() > 0)
         {
-            dstMatrix[i] = (F32)src.matrix[i];
+            static LLCachedControl<U32> anim_idx(gSavedSettings, "GLTFAnimationIndex", 0);
+            static LLCachedControl<F32> anim_speed(gSavedSettings, "GLTFAnimationSpeed", 1.f);
+
+            U32 idx = llclamp(anim_idx(), 0U, mAnimations.size() - 1);
+            mAnimations[idx].update(*this, dt*anim_speed);
         }
 
-        mMatrixValid = true;
+        updateTransforms();
+
+        for (auto& skin : mSkins)
+        {
+            skin.uploadMatrixPalette(*this);
+        }
     }
-    else if (!src.rotation.empty() || !src.translation.empty() || !src.scale.empty())
+}
+
+bool Asset::prep()
+{
+    // check required extensions and fail if not supported
+    bool unsupported = false;
+    for (auto& extension : mExtensionsRequired)
     {
-        // node has rotation/translation/scale, convert to matrix
-        if (src.rotation.size() == 4)
+        if (ExtensionsSupported.find(extension) == ExtensionsSupported.end())
         {
-            mRotation = glh::quaternionf((F32)src.rotation[0], (F32)src.rotation[1], (F32)src.rotation[2], (F32)src.rotation[3]);
+            LL_WARNS() << "Unsupported extension: " << extension << LL_ENDL;
+            unsupported = true;
         }
+    }
 
-        if (src.translation.size() == 3)
+    if (unsupported)
+    {
+        return false;
+    }
+
+    // do buffers first as other resources depend on them
+    for (auto& buffer : mBuffers)
+    {
+        if (!buffer.prep(*this))
         {
-            mTranslation = glh::vec3f((F32)src.translation[0], (F32)src.translation[1], (F32)src.translation[2]);
+            return false;
         }
+    }
 
-        glh::vec3f scale;
-        if (src.scale.size() == 3)
+    for (auto& image : mImages)
+    {
+        if (!image.prep(*this))
         {
-            mScale = glh::vec3f((F32)src.scale[0], (F32)src.scale[1], (F32)src.scale[2]);
+            return false;
         }
-        else
+    }
+
+    for (auto& mesh : mMeshes)
+    {
+        if (!mesh.prep(*this))
         {
-            mScale.set_value(1.f, 1.f, 1.f);
+            return false;
         }
+    }
 
-        mTRSValid = true;
+    for (auto& animation : mAnimations)
+    {
+        if (!animation.prep(*this))
+        {
+            return false;
+        }
     }
-    else
+
+    for (auto& skin : mSkins)
     {
-        // node specifies no transformation, set to identity
-        mMatrix.setIdentity();
+        if (!skin.prep(*this))
+        {
+            return false;
+        }
     }
 
-    mChildren = src.children;
-    mMesh = src.mesh;
-    mSkin = src.skin;
-    mName = src.name;
+    return true;
+}
 
-    return *this;
+Asset::Asset(const Value& src)
+{
+    *this = src;
 }
 
-void Asset::render(bool opaque, bool rigged)
+bool Asset::load(std::string_view filename)
 {
-    if (rigged)
-    {
-        gGL.loadIdentity();
-    }
+    mFilename = filename;
+    std::string ext = gDirUtilp->getExtension(mFilename);
 
-    for (auto& node : mNodes)
+    std::ifstream file(filename.data(), std::ios::binary);
+    if (file.is_open())
     {
-        if (node.mSkin != INVALID_INDEX)
+        std::string str((std::istreambuf_iterator<char>(file)), std::istreambuf_iterator<char>());
+        file.close();
+
+        if (ext == "gltf")
         {
-            if (rigged)
-            {
-                Skin& skin = mSkins[node.mSkin];
-                skin.uploadMatrixPalette(*this, node);
-            }
-            else
-            {
-                //skip static nodes if we're rendering rigged
-                continue;
-            }
+            Value val = parse(str);
+            *this = val;
+            return prep();
         }
-        else if (rigged)
+        else if (ext == "glb")
         {
-            // skip rigged nodes if we're not rendering rigged
-            continue;
+            return loadBinary(str);
         }
+        else
+        {
+            LL_WARNS() << "Unsupported file type: " << ext << LL_ENDL;
+            return false;
+        }
+    }
+    else
+    {
+        LL_WARNS() << "Failed to open file: " << filename << LL_ENDL;
+        return false;
+    }
 
+    return false;
+}
 
-        if (node.mMesh != INVALID_INDEX)
+bool Asset::loadBinary(const std::string& data)
+{
+    // load from binary gltf
+    const U8* ptr = (const U8*)data.data();
+    const U8* end = ptr + data.size();
+
+    if (end - ptr < 12)
+    {
+        LL_WARNS("GLTF") << "GLB file too short" << LL_ENDL;
+        return false;
+    }
+
+    U32 magic = *(U32*)ptr;
+    ptr += 4;
+
+    if (magic != 0x46546C67)
+    {
+        LL_WARNS("GLTF") << "Invalid GLB magic" << LL_ENDL;
+        return false;
+    }
+
+    U32 version = *(U32*)ptr;
+    ptr += 4;
+
+    if (version != 2)
+    {
+        LL_WARNS("GLTF") << "Unsupported GLB version" << LL_ENDL;
+        return false;
+    }
+
+    U32 length = *(U32*)ptr;
+    ptr += 4;
+
+    if (length != data.size())
+    {
+        LL_WARNS("GLTF") << "GLB length mismatch" << LL_ENDL;
+        return false;
+    }
+
+    U32 chunkLength = *(U32*)ptr;
+    ptr += 4;
+
+    if (end - ptr < chunkLength + 8)
+    {
+        LL_WARNS("GLTF") << "GLB chunk too short" << LL_ENDL;
+        return false;
+    }
+
+    U32 chunkType = *(U32*)ptr;
+    ptr += 4;
+
+    if (chunkType != 0x4E4F534A)
+    {
+        LL_WARNS("GLTF") << "Invalid GLB chunk type" << LL_ENDL;
+        return false;
+    }
+
+    Value val = parse(std::string_view((const char*)ptr, chunkLength));
+    *this = val;
+
+    if (mBuffers.size() > 0 && mBuffers[0].mUri.empty())
+    {
+        // load binary chunk
+        ptr += chunkLength;
+
+        if (end - ptr < 8)
         {
-            Mesh& mesh = mMeshes[node.mMesh];
-            for (auto& primitive : mesh.mPrimitives)
-            {
-                if (!rigged)
-                {
-                    gGL.loadMatrix((F32*)node.mRenderMatrix.mMatrix);
-                }
-                bool cull = true;
-                if (primitive.mMaterial != INVALID_INDEX)
-                {
-                    Material& material = mMaterials[primitive.mMaterial];
+            LL_WARNS("GLTF") << "GLB chunk too short" << LL_ENDL;
+            return false;
+        }
 
-                    if ((material.mMaterial->mAlphaMode == LLGLTFMaterial::ALPHA_MODE_BLEND) == opaque)
-                    {
-                        continue;
-                    }
-                    material.mMaterial->bind();
-                    cull = !material.mMaterial->mDoubleSided;
-                }
-                else
-                {
-                    if (!opaque)
-                    {
-                        continue;
-                    }
-                    LLFetchedGLTFMaterial::sDefault.bind();
-                }
+        chunkLength = *(U32*)ptr;
+        ptr += 4;
 
-                LLGLDisable cull_face(!cull ? GL_CULL_FACE : 0);
+        chunkType = *(U32*)ptr;
+        ptr += 4;
 
-                primitive.mVertexBuffer->setBuffer();
-                if (primitive.mVertexBuffer->getNumIndices() > 0)
-                {
-                    primitive.mVertexBuffer->draw(primitive.mGLMode, primitive.mVertexBuffer->getNumIndices(), 0);
-                }
-                else
-                {
-                    primitive.mVertexBuffer->drawArrays(primitive.mGLMode, 0, primitive.mVertexBuffer->getNumVerts());
-                }
+        if (chunkType != 0x004E4942)
+        {
+            LL_WARNS("GLTF") << "Invalid GLB chunk type" << LL_ENDL;
+            return false;
+        }
 
-            }
+        auto& buffer = mBuffers[0];
+
+        if (ptr + buffer.mByteLength <= end)
+        {
+            buffer.mData.resize(buffer.mByteLength);
+            memcpy(buffer.mData.data(), ptr, buffer.mByteLength);
+            ptr += buffer.mByteLength;
+        }
+        else
+        {
+            LL_WARNS("GLTF") << "Buffer too short" << LL_ENDL;
+            return false;
         }
     }
-}
 
-void Asset::renderOpaque()
-{
-    render(true);
+    return prep();
 }
 
-void Asset::renderTransparent()
+const Asset& Asset::operator=(const Value& src)
 {
-    render(false);
-}
+    if (src.is_object())
+    {
+        const object& obj = src.as_object();
 
-void Asset::update()
-{
-    F32 dt = gFrameTimeSeconds - mLastUpdateTime;
+        const auto it = obj.find("asset");
 
-    if (dt > 0.f)
-    {
-        mLastUpdateTime = gFrameTimeSeconds;
-        if (mAnimations.size() > 0)
+        if (it != obj.end())
         {
-            static LLCachedControl<U32> anim_idx(gSavedSettings, "GLTFAnimationIndex", 0);
-            static LLCachedControl<F32> anim_speed(gSavedSettings, "GLTFAnimationSpeed", 1.f);
+            const Value& asset = it->value();
 
-            U32 idx = llclamp(anim_idx(), 0U, mAnimations.size() - 1);
-            mAnimations[idx].update(*this, dt*anim_speed);
+            copy(asset, "version", mVersion);
+            copy(asset, "minVersion", mMinVersion);
+            copy(asset, "generator", mGenerator);
+            copy(asset, "copyright", mCopyright);
+            copy(asset, "extras", mExtras);
         }
 
-        updateTransforms();
+        copy(obj, "scene", mScene);
+        copy(obj, "scenes", mScenes);
+        copy(obj, "nodes", mNodes);
+        copy(obj, "meshes", mMeshes);
+        copy(obj, "materials", mMaterials);
+        copy(obj, "buffers", mBuffers);
+        copy(obj, "bufferViews", mBufferViews);
+        copy(obj, "textures", mTextures);
+        copy(obj, "samplers", mSamplers);
+        copy(obj, "images", mImages);
+        copy(obj, "accessors", mAccessors);
+        copy(obj, "animations", mAnimations);
+        copy(obj, "skins", mSkins);
+        copy(obj, "extensionsUsed", mExtensionsUsed);
+        copy(obj, "extensionsRequired", mExtensionsRequired);
     }
+
+    return *this;
+}
+
+void Asset::serialize(object& dst) const
+{
+    static const std::string sGenerator = "Linden Lab GLTF Prototype v0.1";
+
+    dst["asset"] = object{};
+    object& asset = dst["asset"].get_object();
+
+    write(mVersion, "version", asset);
+    write(mMinVersion, "minVersion", asset, std::string());
+    write(sGenerator, "generator", asset);
+    write(mScene, "scene", dst, INVALID_INDEX);
+    write(mScenes, "scenes", dst);
+    write(mNodes, "nodes", dst);
+    write(mMeshes, "meshes", dst);
+    write(mMaterials, "materials", dst);
+    write(mBuffers, "buffers", dst);
+    write(mBufferViews, "bufferViews", dst);
+    write(mTextures, "textures", dst);
+    write(mSamplers, "samplers", dst);
+    write(mImages, "images", dst);
+    write(mAccessors, "accessors", dst);
+    write(mAnimations, "animations", dst);
+    write(mSkins, "skins", dst);
+    write(mExtensionsUsed, "extensionsUsed", dst);
+    write(mExtensionsRequired, "extensionsRequired", dst);
 }
 
-void Asset::allocateGLResources(const std::string& filename, const tinygltf::Model& model)
+bool Asset::save(const std::string& filename)
 {
-    // do images first as materials may depend on images
+    // get folder path
+    std::string folder = gDirUtilp->getDirName(filename);
+
+    // save images
     for (auto& image : mImages)
     {
-        image.allocateGLResources();
+        if (!image.save(*this, folder))
+        {
+            return false;
+        }
     }
 
-    // do materials before meshes as meshes may depend on materials
-    for (U32 i = 0; i < mMaterials.size(); ++i)
+    // save buffers
+    // NOTE: save buffers after saving images as saving images
+    // may remove image data from buffers
+    for (auto& buffer : mBuffers)
     {
-        mMaterials[i].allocateGLResources(*this);
-        LLTinyGLTFHelper::getMaterialFromModel(filename, model, i, mMaterials[i].mMaterial, mMaterials[i].mName, true);
+        if (!buffer.save(*this, folder))
+        {
+            return false;
+        }
     }
 
-    for (auto& mesh : mMeshes)
-    {
-        mesh.allocateGLResources(*this);
-    }
+    // save .gltf
+    object obj;
+    serialize(obj);
+    std::string buffer = boost::json::serialize(obj, {});
+    std::ofstream file(filename, std::ios::binary);
+    file.write(buffer.c_str(), buffer.size());
 
-    for (auto& animation : mAnimations)
+    return true;
+}
+
+void Asset::eraseBufferView(S32 bufferView)
+{
+    mBufferViews.erase(mBufferViews.begin() + bufferView);
+
+    for (auto& accessor : mAccessors)
     {
-        animation.allocateGLResources(*this);
+        if (accessor.mBufferView > bufferView)
+        {
+            accessor.mBufferView--;
+        }
     }
 
-    for (auto& skin : mSkins)
+    for (auto& image : mImages)
     {
-        skin.allocateGLResources(*this);
+        if (image.mBufferView > bufferView)
+        {
+            image.mBufferView--;
+        }
     }
+
 }
 
-const Asset& Asset::operator=(const tinygltf::Model& src)
+LLViewerFetchedTexture* fetch_texture(const LLUUID& id);
+
+bool Image::prep(Asset& asset)
 {
-    mScenes.resize(src.scenes.size());
-    for (U32 i = 0; i < src.scenes.size(); ++i)
-    {
-        mScenes[i] = src.scenes[i];
+    LLUUID id;
+    if (mUri.size() == UUID_STR_SIZE && LLUUID::parseUUID(mUri, &id) && id.notNull())
+    { // loaded from an asset, fetch the texture from the asset system
+        mTexture = fetch_texture(id);
     }
-
-    mNodes.resize(src.nodes.size());
-    for (U32 i = 0; i < src.nodes.size(); ++i)
-    {
-        mNodes[i] = src.nodes[i];
+    else if (mUri.find("data:") == 0)
+    { // embedded in a data URI, load the texture from the URI
+        LL_WARNS() << "Data URIs not yet supported" << LL_ENDL;
+        return false;
     }
+    else if (mBufferView != INVALID_INDEX)
+    { // embedded in a buffer, load the texture from the buffer
+        BufferView& bufferView = asset.mBufferViews[mBufferView];
+        Buffer& buffer = asset.mBuffers[bufferView.mBuffer];
 
-    mMeshes.resize(src.meshes.size());
-    for (U32 i = 0; i < src.meshes.size(); ++i)
-    {
-        mMeshes[i] = src.meshes[i];
-    }
+        U8* data = buffer.mData.data() + bufferView.mByteOffset;
 
-    mMaterials.resize(src.materials.size());
-    for (U32 i = 0; i < src.materials.size(); ++i)
-    {
-        mMaterials[i] = src.materials[i];
+        mTexture = LLViewerTextureManager::getFetchedTextureFromMemory(data, bufferView.mByteLength, mMimeType);
+
+        if (mTexture.isNull())
+        {
+            LL_WARNS("GLTF") << "Failed to load image from buffer:" << LL_ENDL;
+            LL_WARNS("GLTF") << "  image: " << mName << LL_ENDL;
+            LL_WARNS("GLTF") << "  mimeType: " << mMimeType << LL_ENDL;
+
+            return false;
+        }
     }
+    else if (!asset.mFilename.empty() && !mUri.empty())
+    { // loaded locally and not embedded, load the texture as a local preview
+        std::string dir = gDirUtilp->getDirName(asset.mFilename);
+        std::string img_file = dir + gDirUtilp->getDirDelimiter() + mUri;
+
+        LLUUID tracking_id = LLLocalBitmapMgr::getInstance()->addUnit(img_file);
+        if (tracking_id.notNull())
+        {
+            LLUUID world_id = LLLocalBitmapMgr::getInstance()->getWorldID(tracking_id);
+            mTexture = LLViewerTextureManager::getFetchedTexture(world_id);
+        }
+        else
+        {
+            LL_WARNS("GLTF") << "Failed to load image from file:" << LL_ENDL;
+            LL_WARNS("GLTF") << "  image: " << mName << LL_ENDL;
+            LL_WARNS("GLTF") << "  file: " << img_file << LL_ENDL;
 
-    mBuffers.resize(src.buffers.size());
-    for (U32 i = 0; i < src.buffers.size(); ++i)
+            return false;
+        }
+    }
+    else
     {
-        mBuffers[i] = src.buffers[i];
+        LL_WARNS("GLTF") << "Failed to load image: " << mName << LL_ENDL;
+        return false;
     }
 
-    mBufferViews.resize(src.bufferViews.size());
-    for (U32 i = 0; i < src.bufferViews.size(); ++i)
+    return true;
+}
+
+
+void Image::clearData(Asset& asset)
+{
+    if (mBufferView != INVALID_INDEX)
     {
-        mBufferViews[i] = src.bufferViews[i];
+        // remove data from buffer
+        BufferView& bufferView = asset.mBufferViews[mBufferView];
+        Buffer& buffer = asset.mBuffers[bufferView.mBuffer];
+
+        buffer.erase(asset, bufferView.mByteOffset, bufferView.mByteLength);
+
+        asset.eraseBufferView(mBufferView);
     }
 
-    mTextures.resize(src.textures.size());
-    for (U32 i = 0; i < src.textures.size(); ++i)
+    mBufferView = INVALID_INDEX;
+    mWidth = -1;
+    mHeight = -1;
+    mComponent = -1;
+    mBits = -1;
+    mPixelType = -1;
+    mMimeType = "";
+}
+
+bool Image::save(Asset& asset, const std::string& folder)
+{
+    // NOTE:  this *MUST* be a lossless save
+    // Artists use this to save their work repeatedly, so
+    // adding any compression artifacts here will degrade
+    // images over time.
+    std::string name = mName;
+    std::string error;
+    const std::string& delim = gDirUtilp->getDirDelimiter();
+    if (name.empty())
     {
-        mTextures[i] = src.textures[i];
+        S32 idx = this - asset.mImages.data();
+        name = llformat("image_%d", idx);
     }
 
-    mSamplers.resize(src.samplers.size());
-    for (U32 i = 0; i < src.samplers.size(); ++i)
+    if (mBufferView != INVALID_INDEX)
     {
-        mSamplers[i] = src.samplers[i];
-    }
+        // we have the bytes of the original image, save that out in its
+        // original format
+        BufferView& bufferView = asset.mBufferViews[mBufferView];
+        Buffer& buffer = asset.mBuffers[bufferView.mBuffer];
+
+        std::string extension;
+
+        if (mMimeType == "image/jpeg")
+        {
+            extension = ".jpg";
+        }
+        else if (mMimeType == "image/png")
+        {
+            extension = ".png";
+        }
+        else
+        {
+            error = "Unknown mime type, saved as .bin";
+            extension = ".bin";
+        }
+
+        std::string filename = folder + delim + name + extension;
 
-    mImages.resize(src.images.size());
-    for (U32 i = 0; i < src.images.size(); ++i)
+        // set URI to non-j2c file for now, but later we'll want to reference the j2c hash
+        mUri = name + extension;
+
+        std::ofstream file(filename, std::ios::binary);
+        file.write((const char*)buffer.mData.data() + bufferView.mByteOffset, bufferView.mByteLength);
+    }
+    else if (mTexture.notNull())
     {
-        mImages[i] = src.images[i];
+        auto bitmapmgr = LLLocalBitmapMgr::getInstance();
+        if (bitmapmgr->isLocal(mTexture->getID()))
+        {
+            LLUUID tracking_id = bitmapmgr->getTrackingID(mTexture->getID());
+            if (tracking_id.notNull())
+            { // copy original file to destination folder
+                std::string source = bitmapmgr->getFilename(tracking_id);
+                if (gDirUtilp->fileExists(source))
+                {
+                    std::string filename = gDirUtilp->getBaseFileName(source);
+                    std::string dest = folder + delim + filename;
+
+                    LLFile::copy(source, dest);
+                    mUri = filename;
+                }
+                else
+                {
+                    error = "File not found: " + source;
+                }
+            }
+            else
+            {
+                error = "Local image missing.";
+            }
+        }
+        else if (!mUri.empty())
+        {
+            std::string from_dir = gDirUtilp->getDirName(asset.mFilename);
+            std::string base_filename = gDirUtilp->getBaseFileName(mUri);
+            std::string filename = from_dir + delim + base_filename;
+            if (gDirUtilp->fileExists(filename))
+            {
+                std::string dest = folder + delim + base_filename;
+                LLFile::copy(filename, dest);
+                mUri = base_filename;
+            }
+            else
+            {
+                error = "Original image file not found: " + filename;
+            }
+        }
+        else
+        {
+            error = "Image is not a local image and has no uri, cannot save.";
+        }
     }
 
-    mAccessors.resize(src.accessors.size());
-    for (U32 i = 0; i < src.accessors.size(); ++i)
+    if (!error.empty())
     {
-        mAccessors[i] = src.accessors[i];
+        LL_WARNS("GLTF") << "Failed to save " << name << ": " << error << LL_ENDL;
+        return false;
     }
 
-    mAnimations.resize(src.animations.size());
-    for (U32 i = 0; i < src.animations.size(); ++i)
+    clearData(asset);
+
+    return true;
+}
+
+void Material::TextureInfo::serialize(object& dst) const
+{
+    write(mIndex, "index", dst, INVALID_INDEX);
+    write(mTexCoord, "texCoord", dst, 0);
+    write_extensions(dst, &mTextureTransform, "KHR_texture_transform");
+}
+
+S32 Material::TextureInfo::getTexCoord() const
+{
+    if (mTextureTransform.mPresent && mTextureTransform.mTexCoord != INVALID_INDEX)
     {
-        mAnimations[i] = src.animations[i];
+        return mTextureTransform.mTexCoord;
     }
+    return mTexCoord;
+}
+
+bool Material::isMultiUV() const
+{
+    return mPbrMetallicRoughness.mBaseColorTexture.getTexCoord() != 0 ||
+        mPbrMetallicRoughness.mMetallicRoughnessTexture.getTexCoord() != 0 ||
+        mNormalTexture.getTexCoord() != 0 ||
+        mOcclusionTexture.getTexCoord() != 0 ||
+        mEmissiveTexture.getTexCoord() != 0;
+}
 
-    mSkins.resize(src.skins.size());
-    for (U32 i = 0; i < src.skins.size(); ++i)
+const Material::TextureInfo& Material::TextureInfo::operator=(const Value& src)
+{
+    if (src.is_object())
     {
-        mSkins[i] = src.skins[i];
+        copy(src, "index", mIndex);
+        copy(src, "texCoord", mTexCoord);
+        copy_extensions(src, "KHR_texture_transform", &mTextureTransform);
     }
- 
+
     return *this;
 }
 
-const Material& Material::operator=(const tinygltf::Material& src)
+bool Material::TextureInfo::operator==(const Material::TextureInfo& rhs) const
 {
-    mName = src.name;
-    return *this;
+    return mIndex == rhs.mIndex && mTexCoord == rhs.mTexCoord;
+}
+
+bool Material::TextureInfo::operator!=(const Material::TextureInfo& rhs) const
+{
+    return !(*this == rhs);
 }
 
-void Material::allocateGLResources(Asset& asset)
+void Material::OcclusionTextureInfo::serialize(object& dst) const
 {
-    // allocate material
-    mMaterial = new LLFetchedGLTFMaterial();
+    TextureInfo::serialize(dst);
+    write(mStrength, "strength", dst, 1.f);
 }
 
-const Mesh& Mesh::operator=(const tinygltf::Mesh& src)
+const Material::OcclusionTextureInfo& Material::OcclusionTextureInfo::operator=(const Value& src)
 {
-    mPrimitives.resize(src.primitives.size());
-    for (U32 i = 0; i < src.primitives.size(); ++i)
+    TextureInfo::operator=(src);
+
+    if (src.is_object())
     {
-        mPrimitives[i] = src.primitives[i];
+        copy(src, "strength", mStrength);
     }
 
-    mWeights = src.weights;
-    mName = src.name;
-
     return *this;
 }
 
-void Mesh::allocateGLResources(Asset& asset)
+void Material::NormalTextureInfo::serialize(object& dst) const
 {
-    for (auto& primitive : mPrimitives)
+    TextureInfo::serialize(dst);
+    write(mScale, "scale", dst, 1.f);
+}
+
+const Material::NormalTextureInfo& Material::NormalTextureInfo::operator=(const Value& src)
+{
+    TextureInfo::operator=(src);
+    if (src.is_object())
     {
-        primitive.allocateGLResources(asset);
+        copy(src, "index", mIndex);
+        copy(src, "texCoord", mTexCoord);
+        copy(src, "scale", mScale);
     }
+
+    return *this;
 }
 
-const Scene& Scene::operator=(const tinygltf::Scene& src)
+const Material::PbrMetallicRoughness& Material::PbrMetallicRoughness::operator=(const Value& src)
 {
-    mNodes = src.nodes;
-    mName = src.name;
+    if (src.is_object())
+    {
+        copy(src, "baseColorFactor", mBaseColorFactor);
+        copy(src, "baseColorTexture", mBaseColorTexture);
+        copy(src, "metallicFactor", mMetallicFactor);
+        copy(src, "roughnessFactor", mRoughnessFactor);
+        copy(src, "metallicRoughnessTexture", mMetallicRoughnessTexture);
+    }
 
     return *this;
 }
 
-const Texture& Texture::operator=(const tinygltf::Texture& src)
+void Material::PbrMetallicRoughness::serialize(object& dst) const
 {
-    mSampler = src.sampler;
-    mSource = src.source;
-    mName = src.name;
+    write(mBaseColorFactor, "baseColorFactor", dst, vec4(1.f, 1.f, 1.f, 1.f));
+    write(mBaseColorTexture, "baseColorTexture", dst);
+    write(mMetallicFactor, "metallicFactor", dst, 1.f);
+    write(mRoughnessFactor, "roughnessFactor", dst, 1.f);
+    write(mMetallicRoughnessTexture, "metallicRoughnessTexture", dst);
+}
 
-    return *this;
+bool Material::PbrMetallicRoughness::operator==(const Material::PbrMetallicRoughness& rhs) const
+{
+    return mBaseColorFactor == rhs.mBaseColorFactor &&
+        mBaseColorTexture == rhs.mBaseColorTexture &&
+        mMetallicFactor == rhs.mMetallicFactor &&
+        mRoughnessFactor == rhs.mRoughnessFactor &&
+        mMetallicRoughnessTexture == rhs.mMetallicRoughnessTexture;
 }
 
-const Sampler& Sampler::operator=(const tinygltf::Sampler& src)
+bool Material::PbrMetallicRoughness::operator!=(const Material::PbrMetallicRoughness& rhs) const
 {
-    mMagFilter = src.magFilter;
-    mMinFilter = src.minFilter;
-    mWrapS = src.wrapS;
-    mWrapT = src.wrapT;
-    mName = src.name;
+    return !(*this == rhs);
+}
 
+const Material::Unlit& Material::Unlit::operator=(const Value& src)
+{
+    mPresent = true;
     return *this;
 }
 
-void Skin::uploadMatrixPalette(Asset& asset, Node& node)
+void Material::Unlit::serialize(object& dst) const
 {
-    // prepare matrix palette
+    // no members and object has already been created, nothing to do
+}
 
-    // modelview will be applied by the shader, so assume matrix palette is in asset space
-    std::vector<glh::matrix4f> t_mp;
+void TextureTransform::getPacked(F32* packed) const
+{
+    packed[0] = mScale.x;
+    packed[1] = mScale.y;
+    packed[2] = mRotation;
+    packed[3] = mOffset.x;
+    packed[4] = mOffset.y;
+
+    packed[5] = packed[6] = packed[7] = 0.f;
+}
 
-    t_mp.resize(mJoints.size());
 
-    for (U32 i = 0; i < mJoints.size(); ++i)
+const TextureTransform& TextureTransform::operator=(const Value& src)
+{
+    mPresent = true;
+    if (src.is_object())
     {
-        Node& joint = asset.mNodes[mJoints[i]];
-        
-        //t_mp[i].set_value(joint.mRenderMatrix.getF32ptr());
-        //t_mp[i] = t_mp[i] * mInverseBindMatricesData[i];
+        copy(src, "offset", mOffset);
+        copy(src, "rotation", mRotation);
+        copy(src, "scale", mScale);
+        copy(src, "texCoord", mTexCoord);
+    }
+
+    return *this;
+}
+
+void TextureTransform::serialize(object& dst) const
+{
+    write(mOffset, "offset", dst, vec2(0.f, 0.f));
+    write(mRotation, "rotation", dst, 0.f);
+    write(mScale, "scale", dst, vec2(1.f, 1.f));
+    write(mTexCoord, "texCoord", dst, -1);
+}
 
-        //t_mp[i].set_value(joint.mRenderMatrix.getF32ptr());
-        //t_mp[i] = mInverseBindMatricesData[i] * t_mp[i];
 
-        t_mp[i].set_value(joint.mRenderMatrix.getF32ptr());
-        t_mp[i] = t_mp[i] * mInverseBindMatricesData[i];
+void Material::serialize(object& dst) const
+{
+    write(mName, "name", dst);
+    write(mEmissiveFactor, "emissiveFactor", dst, vec3(0.f, 0.f, 0.f));
+    write(mPbrMetallicRoughness, "pbrMetallicRoughness", dst);
+    write(mNormalTexture, "normalTexture", dst);
+    write(mOcclusionTexture, "occlusionTexture", dst);
+    write(mEmissiveTexture, "emissiveTexture", dst);
+    write(mAlphaMode, "alphaMode", dst, Material::AlphaMode::OPAQUE);
+    write(mAlphaCutoff, "alphaCutoff", dst, 0.5f);
+    write(mDoubleSided, "doubleSided", dst, false);
+    write_extensions(dst, &mUnlit, "KHR_materials_unlit");
+}
 
+const Material& Material::operator=(const Value& src)
+{
+    if (src.is_object())
+    {
+        copy(src, "name", mName);
+        copy(src, "emissiveFactor", mEmissiveFactor);
+        copy(src, "pbrMetallicRoughness", mPbrMetallicRoughness);
+        copy(src, "normalTexture", mNormalTexture);
+        copy(src, "occlusionTexture", mOcclusionTexture);
+        copy(src, "emissiveTexture", mEmissiveTexture);
+        copy(src, "alphaMode", mAlphaMode);
+        copy(src, "alphaCutoff", mAlphaCutoff);
+        copy(src, "doubleSided", mDoubleSided);
+        copy_extensions(src,
+            "KHR_materials_unlit", &mUnlit );
     }
+    return *this;
+}
 
-    std::vector<F32> glmp;
 
-    glmp.resize(mJoints.size() * 12);
+void Mesh::serialize(object& dst) const
+{
+    write(mPrimitives, "primitives", dst);
+    write(mWeights, "weights", dst);
+    write(mName, "name", dst);
+}
 
-    F32* mp = glmp.data();
+const Mesh& Mesh::operator=(const Value& src)
+{
+    if (src.is_object())
+    {
+        copy(src, "primitives", mPrimitives);
+        copy(src, "weights", mWeights);
+        copy(src, "name", mName);
+    }
 
-    for (U32 i = 0; i < mJoints.size(); ++i)
+    return *this;
+}
+
+bool Mesh::prep(Asset& asset)
+{
+    for (auto& primitive : mPrimitives)
     {
-        F32* m = (F32*)t_mp[i].m;
+        if (!primitive.prep(asset))
+        {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+void Scene::serialize(object& dst) const
+{
+    write(mNodes, "nodes", dst);
+    write(mName, "name", dst);
+}
 
-        U32 idx = i * 12;
+const Scene& Scene::operator=(const Value& src)
+{
+    copy(src, "nodes", mNodes);
+    copy(src, "name", mName);
 
-        mp[idx + 0] = m[0];
-        mp[idx + 1] = m[1];
-        mp[idx + 2] = m[2];
-        mp[idx + 3] = m[12];
+    return *this;
+}
 
-        mp[idx + 4] = m[4];
-        mp[idx + 5] = m[5];
-        mp[idx + 6] = m[6];
-        mp[idx + 7] = m[13];
+void Texture::serialize(object& dst) const
+{
+    write(mSampler, "sampler", dst, INVALID_INDEX);
+    write(mSource, "source", dst, INVALID_INDEX);
+    write(mName, "name", dst);
+}
 
-        mp[idx + 8] = m[8];
-        mp[idx + 9] = m[9];
-        mp[idx + 10] = m[10];
-        mp[idx + 11] = m[14];
+const Texture& Texture::operator=(const Value& src)
+{
+    if (src.is_object())
+    {
+        copy(src, "sampler", mSampler);
+        copy(src, "source", mSource);
+        copy(src, "name", mName);
     }
 
-    LLGLSLShader::sCurBoundShaderPtr->uniformMatrix3x4fv(LLViewerShaderMgr::AVATAR_MATRIX,
-        mJoints.size(),
-        FALSE,
-        (GLfloat*)glmp.data());
+    return *this;
+}
+
+void Sampler::serialize(object& dst) const
+{
+    write(mMagFilter, "magFilter", dst, LINEAR);
+    write(mMinFilter, "minFilter", dst, LINEAR_MIPMAP_LINEAR);
+    write(mWrapS, "wrapS", dst, REPEAT);
+    write(mWrapT, "wrapT", dst, REPEAT);
+    write(mName, "name", dst);
 }
 
+const Sampler& Sampler::operator=(const Value& src)
+{
+    copy(src, "magFilter", mMagFilter);
+    copy(src, "minFilter", mMinFilter);
+    copy(src, "wrapS", mWrapS);
+    copy(src, "wrapT", mWrapT);
+    copy(src, "name", mName);
+
+    return *this;
+}
+
+
diff --git a/indra/newview/gltf/asset.h b/indra/newview/gltf/asset.h
index 5ceac74a8a..ea3f7d480a 100644
--- a/indra/newview/gltf/asset.h
+++ b/indra/newview/gltf/asset.h
@@ -28,13 +28,20 @@
 
 #include "llvertexbuffer.h"
 #include "llvolumeoctree.h"
-#include "../lltinygltfhelper.h"
 #include "accessor.h"
 #include "primitive.h"
 #include "animation.h"
+#include "boost/json.hpp"
+#include "common.h"
+#include "../llviewertexture.h"
 
 extern F32SecondsImplicit       gFrameTimeSeconds;
 
+// wingdi defines OPAQUE, which conflicts with our enum
+#if defined(OPAQUE)
+#undef OPAQUE
+#endif
+
 // LL GLTF Implementation
 namespace LL
 {
@@ -42,18 +49,117 @@ namespace LL
     {
         class Asset;
 
+        class Extension
+        {
+        public:
+            // true if this extension is present in the gltf file
+            // otherwise false
+            bool mPresent = false;
+        };
+
+        class TextureTransform : public Extension // KHR_texture_transform implementation
+        {
+        public:
+            vec2 mOffset = vec2(0.f, 0.f);
+            F32 mRotation = 0.f;
+            vec2 mScale = vec2(1.f, 1.f);
+            S32 mTexCoord = INVALID_INDEX;
+
+            // get the texture transform as a packed array of floats
+            // dst MUST point to at least 8 floats
+            void getPacked(F32* dst) const;
+
+            const TextureTransform& operator=(const Value& src);
+            void serialize(boost::json::object& dst) const;
+        };
+
         class Material
         {
         public:
-            // use LLFetchedGLTFMaterial for now, but eventually we'll want to use
-            // a more flexible GLTF material implementation instead of the fixed packing
-            // version we use for sharable GLTF material assets
-            LLPointer<LLFetchedGLTFMaterial> mMaterial;
+
+            class Unlit : public Extension // KHR_materials_unlit implementation
+            {
+            public:
+                const Unlit& operator=(const Value& src);
+                void serialize(boost::json::object& dst) const;
+            };
+
+            enum class AlphaMode
+            {
+                OPAQUE,
+                MASK,
+                BLEND
+            };
+
+            class TextureInfo
+            {
+            public:
+                S32 mIndex = INVALID_INDEX;
+                S32 mTexCoord = 0;
+
+                TextureTransform mTextureTransform;
+
+                bool operator==(const TextureInfo& rhs) const;
+                bool operator!=(const TextureInfo& rhs) const;
+
+                // get the UV channel that should be used for sampling this texture
+                // returns mTextureTransform.mTexCoord if present and valid, otherwise mTexCoord
+                S32 getTexCoord() const;
+
+                const TextureInfo& operator=(const Value& src);
+                void serialize(boost::json::object& dst) const;
+            };
+
+            class NormalTextureInfo : public TextureInfo
+            {
+            public:
+                F32 mScale = 1.0f;
+
+                const NormalTextureInfo& operator=(const Value& src);
+                void serialize(boost::json::object& dst) const;
+            };
+
+            class OcclusionTextureInfo : public TextureInfo
+            {
+            public:
+                F32 mStrength = 1.0f;
+
+                const OcclusionTextureInfo& operator=(const Value& src);
+                void serialize(boost::json::object& dst) const;
+            };
+
+            class PbrMetallicRoughness
+            {
+            public:
+                vec4 mBaseColorFactor = vec4(1.f,1.f,1.f,1.f);
+                TextureInfo mBaseColorTexture;
+                F32 mMetallicFactor = 1.0f;
+                F32 mRoughnessFactor = 1.0f;
+                TextureInfo mMetallicRoughnessTexture;
+
+                bool operator==(const PbrMetallicRoughness& rhs) const;
+                bool operator!=(const PbrMetallicRoughness& rhs) const;
+                const PbrMetallicRoughness& operator=(const Value& src);
+                void serialize(boost::json::object& dst) const;
+            };
+
+
+            PbrMetallicRoughness mPbrMetallicRoughness;
+            NormalTextureInfo mNormalTexture;
+            OcclusionTextureInfo mOcclusionTexture;
+            TextureInfo mEmissiveTexture;
+
             std::string mName;
+            vec3 mEmissiveFactor = vec3(0.f, 0.f, 0.f);
+            AlphaMode mAlphaMode = AlphaMode::OPAQUE;
+            F32 mAlphaCutoff = 0.5f;
+            bool mDoubleSided = false;
+            Unlit mUnlit;
 
-            const Material& operator=(const tinygltf::Material& src);
+            bool isMultiUV() const;
 
-            void allocateGLResources(Asset& asset);
+            const Material& operator=(const Value& src);
+            void serialize(boost::json::object& dst) const;
         };
 
         class Mesh
@@ -63,22 +169,23 @@ namespace LL
             std::vector<double> mWeights;
             std::string mName;
 
-            const Mesh& operator=(const tinygltf::Mesh& src);
+            const Mesh& operator=(const Value& src);
+            void serialize(boost::json::object& dst) const;
 
-            void allocateGLResources(Asset& asset);
+            bool prep(Asset& asset);
         };
 
         class Node
         {
         public:
-            LLMatrix4a mMatrix; //local transform
-            LLMatrix4a mRenderMatrix; //transform for rendering
-            LLMatrix4a mAssetMatrix; //transform from local to asset space
-            LLMatrix4a mAssetMatrixInv; //transform from asset to local space
+            mat4 mMatrix = glm::identity<mat4>(); //local transform
+            mat4 mRenderMatrix; //transform for rendering
+            mat4 mAssetMatrix; //transform from local to asset space
+            mat4 mAssetMatrixInv; //transform from asset to local space
 
-            glh::vec3f mTranslation;
-            glh::quaternionf mRotation;
-            glh::vec3f mScale;
+            vec3  mTranslation = vec3(0,0,0);
+            quat mRotation = glm::identity<quat>();
+            vec3 mScale = vec3(1.f,1.f,1.f);
 
             // if true, mMatrix is valid and up to date
             bool mMatrixValid = false;
@@ -96,14 +203,15 @@ namespace LL
 
             std::string mName;
 
-            const Node& operator=(const tinygltf::Node& src);
+            const Node& operator=(const Value& src);
+            void serialize(boost::json::object& dst) const;
 
             // Set mRenderMatrix to a transform that can be used for the current render pass
             // modelview -- parent's render matrix
-            void updateRenderTransforms(Asset& asset, const LLMatrix4a& modelview);
+            void updateRenderTransforms(Asset& asset, const mat4& modelview);
 
             // update mAssetMatrix and mAssetMatrixInv
-            void updateTransforms(Asset& asset, const LLMatrix4a& parentMatrix);
+            void updateTransforms(Asset& asset, const mat4& parentMatrix);
 
             // ensure mMatrix is valid -- if mMatrixValid is false and mTRSValid is true, will update mMatrix to match Translation/Rotation/Scale
             void makeMatrixValid();
@@ -113,30 +221,35 @@ namespace LL
 
             // Set rotation of this node
             // SIDE EFFECT: invalidates mMatrix
-            void setRotation(const glh::quaternionf& rotation);
+            void setRotation(const quat& rotation);
 
             // Set translation of this node
             // SIDE EFFECT: invalidates mMatrix
-            void setTranslation(const glh::vec3f& translation);
+            void setTranslation(const vec3& translation);
 
             // Set scale of this node
             // SIDE EFFECT: invalidates mMatrix
-            void setScale(const glh::vec3f& scale);
+            void setScale(const vec3& scale);
         };
 
         class Skin
         {
         public:
+            ~Skin();
+
             S32 mInverseBindMatrices = INVALID_INDEX;
             S32 mSkeleton = INVALID_INDEX;
+
+            U32 mUBO = 0;
             std::vector<S32> mJoints;
             std::string mName;
-            std::vector<glh::matrix4f> mInverseBindMatricesData;
+            std::vector<mat4> mInverseBindMatricesData;
 
-            void allocateGLResources(Asset& asset);
-            void uploadMatrixPalette(Asset& asset, Node& node);
+            bool prep(Asset& asset);
+            void uploadMatrixPalette(Asset& asset);
 
-            const Skin& operator=(const tinygltf::Skin& src);
+            const Skin& operator=(const Value& src);
+            void serialize(boost::json::object& dst) const;
         };
 
         class Scene
@@ -145,10 +258,11 @@ namespace LL
             std::vector<S32> mNodes;
             std::string mName;
 
-            const Scene& operator=(const tinygltf::Scene& src);
+            const Scene& operator=(const Value& src);
+            void serialize(boost::json::object& dst) const;
 
             void updateTransforms(Asset& asset);
-            void updateRenderTransforms(Asset& asset, const LLMatrix4a& modelview);
+            void updateRenderTransforms(Asset& asset, const mat4& modelview);
         };
 
         class Texture
@@ -158,19 +272,21 @@ namespace LL
             S32 mSource = INVALID_INDEX;
             std::string mName;
 
-            const Texture& operator=(const tinygltf::Texture& src);
+            const Texture& operator=(const Value& src);
+            void serialize(boost::json::object& dst) const;
         };
 
         class Sampler
         {
         public:
-            S32 mMagFilter;
-            S32 mMinFilter;
-            S32 mWrapS;
-            S32 mWrapT;
+            S32 mMagFilter = LINEAR;
+            S32 mMinFilter = LINEAR_MIPMAP_LINEAR;
+            S32 mWrapS = REPEAT;
+            S32 mWrapT = REPEAT;
             std::string mName;
 
-            const Sampler& operator=(const tinygltf::Sampler& src);
+            const Sampler& operator=(const Value& src);
+            void serialize(boost::json::object& dst) const;
         };
 
         class Image
@@ -179,38 +295,39 @@ namespace LL
             std::string mName;
             std::string mUri;
             std::string mMimeType;
-            std::vector<U8> mData;
-            S32 mWidth;
-            S32 mHeight;
-            S32 mComponent;
-            S32 mBits;
+
+            S32 mBufferView = INVALID_INDEX;
+
+            S32 mWidth = -1;
+            S32 mHeight = -1;
+            S32 mComponent = -1;
+            S32 mBits = -1;
+            S32 mPixelType = -1;
+
             LLPointer<LLViewerFetchedTexture> mTexture;
 
-            const Image& operator=(const tinygltf::Image& src)
-            {
-                mName = src.name;
-                mUri = src.uri;
-                mMimeType = src.mimeType;
-                mData = src.image;
-                mWidth = src.width;
-                mHeight = src.height;
-                mComponent = src.component;
-                mBits = src.bits;
-
-                return *this;
-            }
-
-            void allocateGLResources()
-            {
-                // allocate texture
+            const Image& operator=(const Value& src);
+            void serialize(boost::json::object& dst) const;
+
+            // save image to disk
+            // may remove image data from bufferviews and convert to
+            // file uri if necessary
+            bool save(Asset& asset, const std::string& filename);
+
+            // erase the buffer view associated with this image
+            // free any associated GLTF resources
+            // preserve only uri and name
+            void clearData(Asset& asset);
 
-            }
+            bool prep(Asset& asset);
         };
 
         // C++ representation of a GLTF Asset
-        class Asset : public LLRefCount
+        class Asset
         {
         public:
+
+            static const std::string minVersion_default;
             std::vector<Scene> mScenes;
             std::vector<Node> mNodes;
             std::vector<Mesh> mMeshes;
@@ -223,12 +340,28 @@ namespace LL
             std::vector<Accessor> mAccessors;
             std::vector<Animation> mAnimations;
             std::vector<Skin> mSkins;
+            std::vector<std::string> mExtensionsUsed;
+            std::vector<std::string> mExtensionsRequired;
+
+            std::string mVersion;
+            std::string mGenerator;
+            std::string mMinVersion;
+            std::string mCopyright;
+
+            S32 mScene = INVALID_INDEX;
+            Value mExtras;
+
+            U32 mPendingBuffers = 0;
+
+            // local file this asset was loaded from (if any)
+            std::string mFilename;
 
             // the last time update() was called according to gFrameTimeSeconds
             F32 mLastUpdateTime = gFrameTimeSeconds;
 
-            // prepare the asset for rendering
-            void allocateGLResources(const std::string& filename, const tinygltf::Model& model);
+
+            // prepare for first time use
+            bool prep();
 
             // Called periodically (typically once per frame)
             // Any ongoing work (such as animations) should be handled here
@@ -241,11 +374,7 @@ namespace LL
             void updateTransforms();
 
             // update node render transforms
-            void updateRenderTransforms(const LLMatrix4a& modelview);
-
-            void render(bool opaque, bool rigged = false);
-            void renderOpaque();
-            void renderTransparent();
+            void updateRenderTransforms(const mat4& modelview);
 
             // return the index of the node that the line segment intersects with, or -1 if no hit
             // input and output values must be in this asset's local coordinate frame
@@ -257,8 +386,37 @@ namespace LL
                 S32* primitive_hitp = nullptr           // return the index of the primitive that was hit
             );
 
-            const Asset& operator=(const tinygltf::Model& src);
+            Asset() = default;
+            Asset(const Value& src);
 
+            // load from given file
+            // accepts .gltf and .glb files
+            // Any existing data will be lost
+            // returns result of prep() on success
+            bool load(std::string_view filename);
+
+            // load .glb contents from memory
+            // data - binary contents of .glb file
+            // returns result of prep() on success
+            bool loadBinary(const std::string& data);
+
+            const Asset& operator=(const Value& src);
+            void serialize(boost::json::object& dst) const;
+
+            // save the asset to the given .gltf file
+            // saves images and bins alongside the gltf file
+            bool save(const std::string& filename);
+
+            // remove the bufferview at the given index
+            // updates all bufferview indices in this Asset as needed
+            void eraseBufferView(S32 bufferView);
+
+            // return true if this Asset has been loaded as a local preview
+            // Local previews may be uploaded or exported to disk
+            bool isLocalPreview() { return !mFilename.empty(); }
         };
+
+        Material::AlphaMode gltf_alpha_mode_to_enum(const std::string& alpha_mode);
+        std::string enum_to_gltf_alpha_mode(Material::AlphaMode alpha_mode);
     }
 }
diff --git a/indra/newview/gltf/buffer_util.h b/indra/newview/gltf/buffer_util.h
index 4e6f5901e7..40f9448aaf 100644
--- a/indra/newview/gltf/buffer_util.h
+++ b/indra/newview/gltf/buffer_util.h
@@ -31,60 +31,65 @@
 // whenever we add support for more types
 
 #ifdef _MSC_VER
-#define LL_FUNCSIG __FUNCSIG__ 
+#define LL_FUNCSIG __FUNCSIG__
 #else
 #define LL_FUNCSIG __PRETTY_FUNCTION__
 #endif
 
+#include "accessor.h"
+
 namespace LL
 {
     namespace GLTF
     {
+
+        using string_view = boost::json::string_view;
+
         // copy one Scalar from src to dst
         template<class S, class T>
-        static void copyScalar(S* src, T& dst)
+        inline void copyScalar(S* src, T& dst)
         {
             LL_ERRS() << "TODO: implement " << LL_FUNCSIG << LL_ENDL;
         }
 
         // copy one vec2 from src to dst
         template<class S, class T>
-        static void copyVec2(S* src, T& dst)
+        inline void copyVec2(S* src, T& dst)
         {
             LL_ERRS() << "TODO: implement " << LL_FUNCSIG << LL_ENDL;
         }
 
         // copy one vec3 from src to dst
         template<class S, class T>
-        static void copyVec3(S* src, T& dst)
+        inline void copyVec3(S* src, T& dst)
         {
             LL_ERRS() << "TODO: implement " << LL_FUNCSIG << LL_ENDL;
         }
 
         // copy one vec4 from src to dst
         template<class S, class T>
-        static void copyVec4(S* src, T& dst)
+        inline void copyVec4(S* src, T& dst)
         {
             LL_ERRS() << "TODO: implement " << LL_FUNCSIG << LL_ENDL;
         }
 
-        // copy one vec2 from src to dst
+        // copy one mat2 from src to dst
         template<class S, class T>
-        static void copyMat2(S* src, T& dst)
+        inline void copyMat2(S* src, T& dst)
         {
             LL_ERRS() << "TODO: implement " << LL_FUNCSIG << LL_ENDL;
         }
 
-        // copy one vec3 from src to dst
+        // copy one mat3 from src to dst
         template<class S, class T>
-        static void copyMat3(S* src, T& dst)
+        inline void copyMat3(S* src, T& dst)
         {
             LL_ERRS() << "TODO: implement " << LL_FUNCSIG << LL_ENDL;
         }
 
-        // copy one vec4 from src to dst
+        // copy one mat4 from src to dst
         template<class S, class T>
-        static void copyMat4(S* src, T& dst)
+        inline void copyMat4(S* src, T& dst)
         {
             LL_ERRS() << "TODO: implement " << LL_FUNCSIG << LL_ENDL;
         }
@@ -93,135 +98,138 @@ namespace LL
         // concrete implementations for different types of source and destination
         //=========================================================================================================
 
-// suppress unused function warning -- clang complains here but these specializations are definitely used
-#if defined(__clang__)
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wunused-function"
-#endif
-
         template<>
-        void copyScalar<F32, F32>(F32* src, F32& dst)
+        inline void copyScalar<F32, F32>(F32* src, F32& dst)
         {
             dst = *src;
         }
 
         template<>
-        void copyScalar<U32, U32>(U32* src, U32& dst)
+        inline void copyScalar<U32, U32>(U32* src, U32& dst)
         {
             dst = *src;
         }
 
         template<>
-        void copyScalar<U32, U16>(U32* src, U16& dst)
+        inline void copyScalar<U32, U16>(U32* src, U16& dst)
         {
             dst = *src;
         }
 
         template<>
-        void copyScalar<U16, U16>(U16* src, U16& dst)
+        inline void copyScalar<U16, U16>(U16* src, U16& dst)
         {
             dst = *src;
         }
 
         template<>
-        void copyScalar<U16, U32>(U16* src, U32& dst)
+        inline void copyScalar<U16, U32>(U16* src, U32& dst)
         {
             dst = *src;
         }
 
         template<>
-        void copyScalar<U8, U16>(U8* src, U16& dst)
+        inline void copyScalar<U8, U16>(U8* src, U16& dst)
         {
             dst = *src;
         }
 
         template<>
-        void copyScalar<U8, U32>(U8* src, U32& dst)
+        inline void copyScalar<U8, U32>(U8* src, U32& dst)
         {
             dst = *src;
         }
 
         template<>
-        void copyVec2<F32, LLVector2>(F32* src, LLVector2& dst)
+        inline void copyVec2<F32, LLVector2>(F32* src, LLVector2& dst)
         {
             dst.set(src[0], src[1]);
         }
 
         template<>
-        void copyVec3<F32, glh::vec3f>(F32* src, glh::vec3f& dst)
+        inline void copyVec3<F32, vec3>(F32* src, vec3& dst)
         {
-            dst.set_value(src[0], src[1], src[2]);
+            dst = vec3(src[0], src[1], src[2]);
         }
 
         template<>
-        void copyVec3<F32, LLVector4a>(F32* src, LLVector4a& dst)
+        inline void copyVec3<F32, LLVector4a>(F32* src, LLVector4a& dst)
         {
             dst.load3(src);
         }
 
         template<>
-        void copyVec3<U16, LLColor4U>(U16* src, LLColor4U& dst)
+        inline void copyVec3<U16, LLColor4U>(U16* src, LLColor4U& dst)
         {
             dst.set(src[0], src[1], src[2], 255);
         }
 
         template<>
-        void copyVec4<U8, LLColor4U>(U8* src, LLColor4U& dst)
+        inline void copyVec4<U8, LLColor4U>(U8* src, LLColor4U& dst)
         {
             dst.set(src[0], src[1], src[2], src[3]);
         }
 
         template<>
-        void copyVec4<U16, LLColor4U>(U16* src, LLColor4U& dst)
+        inline void copyVec4<U16, U64>(U16* src, U64& dst)
+        {
+            U16* data = (U16*)&dst;
+            data[0] = src[0];
+            data[1] = src[1];
+            data[2] = src[2];
+            data[3] = src[3];
+        }
+
+        template<>
+        inline void copyVec4<U16, LLColor4U>(U16* src, LLColor4U& dst)
         {
             dst.set(src[0], src[1], src[2], src[3]);
         }
 
         template<>
-        void copyVec4<F32, LLColor4U>(F32* src, LLColor4U& dst)
+        inline void copyVec4<F32, LLColor4U>(F32* src, LLColor4U& dst)
         {
             dst.set(src[0]*255, src[1]*255, src[2]*255, src[3]*255);
         }
 
         template<>
-        void copyVec4<F32, LLVector4a>(F32* src, LLVector4a& dst)
+        inline void copyVec4<F32, LLVector4a>(F32* src, LLVector4a& dst)
         {
             dst.loadua(src);
         }
 
         template<>
-        void copyVec4<U16, LLVector4a>(U16* src, LLVector4a& dst)
+        inline void copyVec4<U16, LLVector4a>(U16* src, LLVector4a& dst)
         {
             dst.set(src[0], src[1], src[2], src[3]);
         }
 
         template<>
-        void copyVec4<U8, LLVector4a>(U8* src, LLVector4a& dst)
+        inline void copyVec4<U8, LLVector4a>(U8* src, LLVector4a& dst)
         {
             dst.set(src[0], src[1], src[2], src[3]);
         }
 
         template<>
-        void copyVec4<F32, glh::quaternionf>(F32* src, glh::quaternionf& dst)
+        inline void copyVec4<F32, quat>(F32* src, quat& dst)
         {
-            dst.set_value(src);
+            dst.x = src[0];
+            dst.y = src[1];
+            dst.z = src[2];
+            dst.w = src[3];
         }
 
         template<>
-        void copyMat4<F32, glh::matrix4f>(F32* src, glh::matrix4f& dst)
+        inline void copyMat4<F32, mat4>(F32* src, mat4& dst)
         {
-            dst.set_value(src);
+            dst = glm::make_mat4(src);
         }
 
-#if defined(__clang__)
-#pragma clang diagnostic pop
-#endif
-
         //=========================================================================================================
 
         // copy from src to dst, stride is the number of bytes between each element in src, count is number of elements to copy
         template<class S, class T>
-        static void copyScalar(S* src, LLStrider<T> dst, S32 stride, S32 count)
+        inline void copyScalar(S* src, LLStrider<T> dst, S32 stride, S32 count)
         {
             for (S32 i = 0; i < count; ++i)
             {
@@ -233,7 +241,7 @@ namespace LL
 
         // copy from src to dst, stride is the number of bytes between each element in src, count is number of elements to copy
         template<class S, class T>
-        static void copyVec2(S* src, LLStrider<T> dst, S32 stride, S32 count)
+        inline void copyVec2(S* src, LLStrider<T> dst, S32 stride, S32 count)
         {
             for (S32 i = 0; i < count; ++i)
             {
@@ -245,7 +253,7 @@ namespace LL
 
         // copy from src to dst, stride is the number of bytes between each element in src, count is number of elements to copy
         template<class S, class T>
-        static void copyVec3(S* src, LLStrider<T> dst, S32 stride, S32 count)
+        inline void copyVec3(S* src, LLStrider<T> dst, S32 stride, S32 count)
         {
             for (S32 i = 0; i < count; ++i)
             {
@@ -257,7 +265,7 @@ namespace LL
 
         // copy from src to dst, stride is the number of bytes between each element in src, count is number of elements to copy
         template<class S, class T>
-        static void copyVec4(S* src, LLStrider<T> dst, S32 stride, S32 count)
+        inline void copyVec4(S* src, LLStrider<T> dst, S32 stride, S32 count)
         {
             for (S32 i = 0; i < count; ++i)
             {
@@ -269,7 +277,7 @@ namespace LL
 
         // copy from src to dst, stride is the number of bytes between each element in src, count is number of elements to copy
         template<class S, class T>
-        static void copyMat2(S* src, LLStrider<T> dst, S32 stride, S32 count)
+        inline void copyMat2(S* src, LLStrider<T> dst, S32 stride, S32 count)
         {
             for (S32 i = 0; i < count; ++i)
             {
@@ -281,7 +289,7 @@ namespace LL
 
         // copy from src to dst, stride is the number of bytes between each element in src, count is number of elements to copy
         template<class S, class T>
-        static void copyMat3(S* src, LLStrider<T> dst, S32 stride, S32 count)
+        inline void copyMat3(S* src, LLStrider<T> dst, S32 stride, S32 count)
         {
             for (S32 i = 0; i < count; ++i)
             {
@@ -293,7 +301,7 @@ namespace LL
 
         // copy from src to dst, stride is the number of bytes between each element in src, count is number of elements to copy
         template<class S, class T>
-        static void copyMat4(S* src, LLStrider<T> dst, S32 stride, S32 count)
+        inline void copyMat4(S* src, LLStrider<T> dst, S32 stride, S32 count)
         {
             for (S32 i = 0; i < count; ++i)
             {
@@ -304,39 +312,39 @@ namespace LL
         }
 
         template<class S, class T>
-        static void copy(Asset& asset, Accessor& accessor, const S* src, LLStrider<T>& dst, S32 byteStride)
+        inline void copy(Asset& asset, Accessor& accessor, const S* src, LLStrider<T>& dst, S32 byteStride)
         {
-            if (accessor.mType == (S32)Accessor::Type::SCALAR)
+            if (accessor.mType == Accessor::Type::SCALAR)
             {
                 S32 stride = byteStride == 0 ? sizeof(S) * 1 : byteStride;
                 copyScalar((S*)src, dst, stride, accessor.mCount);
             }
-            else if (accessor.mType == (S32)Accessor::Type::VEC2)
+            else if (accessor.mType == Accessor::Type::VEC2)
             {
                 S32 stride = byteStride == 0 ? sizeof(S) * 2 : byteStride;
                 copyVec2((S*)src, dst, stride, accessor.mCount);
             }
-            else if (accessor.mType == (S32)Accessor::Type::VEC3)
+            else if (accessor.mType == Accessor::Type::VEC3)
             {
                 S32 stride = byteStride == 0 ? sizeof(S) * 3 : byteStride;
                 copyVec3((S*)src, dst, stride, accessor.mCount);
             }
-            else if (accessor.mType == (S32)Accessor::Type::VEC4)
+            else if (accessor.mType == Accessor::Type::VEC4)
             {
                 S32 stride = byteStride == 0 ? sizeof(S) * 4 : byteStride;
                 copyVec4((S*)src, dst, stride, accessor.mCount);
             }
-            else if (accessor.mType == (S32)Accessor::Type::MAT2)
+            else if (accessor.mType == Accessor::Type::MAT2)
             {
                 S32 stride = byteStride == 0 ? sizeof(S) * 4 : byteStride;
                 copyMat2((S*)src, dst, stride, accessor.mCount);
             }
-            else if (accessor.mType == (S32)Accessor::Type::MAT3)
+            else if (accessor.mType == Accessor::Type::MAT3)
             {
                 S32 stride = byteStride == 0 ? sizeof(S) * 9 : byteStride;
                 copyMat3((S*)src, dst, stride, accessor.mCount);
             }
-            else if (accessor.mType == (S32)Accessor::Type::MAT4)
+            else if (accessor.mType == Accessor::Type::MAT4)
             {
                 S32 stride = byteStride == 0 ? sizeof(S) * 16 : byteStride;
                 copyMat4((S*)src, dst, stride, accessor.mCount);
@@ -349,54 +357,701 @@ namespace LL
 
         // copy data from accessor to strider
         template<class T>
-        static void copy(Asset& asset, Accessor& accessor, LLStrider<T>& dst)
+        inline void copy(Asset& asset, Accessor& accessor, LLStrider<T>& dst)
         {
             const BufferView& bufferView = asset.mBufferViews[accessor.mBufferView];
             const Buffer& buffer = asset.mBuffers[bufferView.mBuffer];
             const U8* src = buffer.mData.data() + bufferView.mByteOffset + accessor.mByteOffset;
 
-            if (accessor.mComponentType == TINYGLTF_COMPONENT_TYPE_FLOAT)
+            switch (accessor.mComponentType)
             {
-                LL::GLTF::copy(asset, accessor, (const F32*)src, dst, bufferView.mByteStride);
+            case Accessor::ComponentType::FLOAT:
+                copy(asset, accessor, (const F32*)src, dst, bufferView.mByteStride);
+                break;
+            case Accessor::ComponentType::UNSIGNED_INT:
+                copy(asset, accessor, (const U32*)src, dst, bufferView.mByteStride);
+                break;
+            case Accessor::ComponentType::SHORT:
+                copy(asset, accessor, (const S16*)src, dst, bufferView.mByteStride);
+                break;
+            case Accessor::ComponentType::UNSIGNED_SHORT:
+                copy(asset, accessor, (const U16*)src, dst, bufferView.mByteStride);
+                break;
+            case Accessor::ComponentType::BYTE:
+                copy(asset, accessor, (const S8*)src, dst, bufferView.mByteStride);
+                break;
+            case Accessor::ComponentType::UNSIGNED_BYTE:
+                copy(asset, accessor, (const U8*)src, dst, bufferView.mByteStride);
+                break;
+            default:
+                LL_ERRS("GLTF") << "Invalid component type" << LL_ENDL;
+                break;
             }
-            else if (accessor.mComponentType == TINYGLTF_COMPONENT_TYPE_UNSIGNED_SHORT)
+        }
+
+        // copy data from accessor to vector
+        template<class T>
+        inline void copy(Asset& asset, Accessor& accessor, std::vector<T>& dst)
+        {
+            dst.resize(accessor.mCount);
+            LLStrider<T> strider = dst.data();
+            copy(asset, accessor, strider);
+        }
+
+
+        //=========================================================================================================
+        // boost::json copying utilities
+        // ========================================================================================================
+
+        //====================== unspecialized base template, single value ===========================
+
+        // to/from Value
+        template<typename T>
+        inline bool copy(const Value& src, T& dst)
+        {
+            dst = src;
+            return true;
+        }
+
+        template<typename T>
+        inline bool write(const T& src, Value& dst)
+        {
+            dst = boost::json::object();
+            src.serialize(dst.as_object());
+            return true;
+        }
+
+        template<typename T>
+        inline bool copy(const Value& src, std::unordered_map<std::string, T>& dst)
+        {
+            if (src.is_object())
             {
-                LL::GLTF::copy(asset, accessor, (const U16*)src, dst, bufferView.mByteStride);
+                const boost::json::object& obj = src.as_object();
+                for (const auto& [key, value] : obj)
+                {
+                    copy<T>(value, dst[key]);
+                }
+                return true;
             }
-            else if (accessor.mComponentType == TINYGLTF_COMPONENT_TYPE_UNSIGNED_INT)
+            return false;
+        }
+
+        template<typename T>
+        inline bool write(const std::unordered_map<std::string, T>& src, Value& dst)
+        {
+            boost::json::object obj;
+            for (const auto& [key, value] : src)
             {
-                LL::GLTF::copy(asset, accessor, (const U32*)src, dst, bufferView.mByteStride);
+                Value v;
+                if (write<T>(value, v))
+                {
+                    obj[key] = v;
+                }
+                else
+                {
+                    return false;
+                }
             }
-            else if (accessor.mComponentType == TINYGLTF_COMPONENT_TYPE_UNSIGNED_BYTE)
+            dst = obj;
+            return true;
+        }
+
+        // to/from array
+        template<typename T>
+        inline bool copy(const Value& src, std::vector<T>& dst)
+        {
+            if (src.is_array())
             {
-                LL::GLTF::copy(asset, accessor, (const U8*)src, dst, bufferView.mByteStride);
+                const boost::json::array& arr = src.get_array();
+                dst.resize(arr.size());
+                for (size_t i = 0; i < arr.size(); ++i)
+                {
+                    copy(arr[i], dst[i]);
+                }
+                return true;
             }
-            else if (accessor.mComponentType == TINYGLTF_COMPONENT_TYPE_SHORT)
+
+            return false;
+        }
+
+        template<typename T>
+        inline bool write(const std::vector<T>& src, Value& dst)
+        {
+            boost::json::array arr;
+            for (const T& t : src)
             {
-                LL::GLTF::copy(asset, accessor, (const S16*)src, dst, bufferView.mByteStride);
+                Value v;
+                if (write(t, v))
+                {
+                    arr.push_back(v);
+                }
+                else
+                {
+                    return false;
+                }
             }
-            else if (accessor.mComponentType == TINYGLTF_COMPONENT_TYPE_BYTE)
+            dst = arr;
+            return true;
+        }
+
+        // to/from object member
+        template<typename T>
+        inline bool copy(const boost::json::object& src, string_view member, T& dst)
+        {
+            auto it = src.find(member);
+            if (it != src.end())
             {
-                LL::GLTF::copy(asset, accessor, (const S8*)src, dst, bufferView.mByteStride);
+                return copy(it->value(), dst);
             }
-            else if (accessor.mComponentType == TINYGLTF_COMPONENT_TYPE_DOUBLE)
+            return false;
+        }
+
+        // always write a member to an object without checking default
+        template<typename T>
+        inline bool write_always(const T& src, string_view member, boost::json::object& dst)
+        {
+            Value& v = dst[member];
+            if (!write(src, v))
             {
-                LL::GLTF::copy(asset, accessor, (const F64*)src, dst, bufferView.mByteStride);
+                dst.erase(member);
+                return false;
             }
-            else
+            return true;
+        }
+
+
+        // to/from extension
+
+        // for internal use only, use copy_extensions instead
+        template<typename T>
+        inline bool _copy_extension(const boost::json::object& extensions, std::string_view member, T* dst)
+        {
+            if (extensions.contains(member))
             {
-                LL_ERRS("GLTF") << "Unsupported component type" << LL_ENDL;
+                return copy(extensions.at(member), *dst);
             }
+
+            return false;
         }
 
-        // copy data from accessor to vector
-        template<class T>
-        static void copy(Asset& asset, Accessor& accessor, std::vector<T>& dst)
+        // Copy all extensions from src.extensions to provided destinations
+        // Usage:
+        //  copy_extensions(src,
+        //                  "KHR_materials_unlit", &mUnlit,
+        //                  "KHR_materials_pbrSpecularGlossiness", &mPbrSpecularGlossiness);
+        // returns true if any of the extensions are copied
+        template<class... Types>
+        inline bool copy_extensions(const boost::json::value& src, Types... args)
         {
-            dst.resize(accessor.mCount);
-            LLStrider<T> strider = dst.data();
-            copy(asset, accessor, strider);
+            // extract the extensions object (don't assume it exists and verify that it is an object)
+            if (src.is_object())
+            {
+                boost::json::object obj = src.get_object();
+                if (obj.contains("extensions"))
+                {
+                    const boost::json::value& extensions = obj.at("extensions");
+                    if (extensions.is_object())
+                    {
+                        const boost::json::object& ext_obj = extensions.as_object();
+                        bool success = false;
+                        // copy each extension, return true if any of them succeed, do not short circuit on success
+                        U32 count = sizeof...(args);
+                        for (U32 i = 0; i < count; i += 2)
+                        {
+                            if (_copy_extension(ext_obj, args...))
+                            {
+                                success = true;
+                            }
+                        }
+                        return success;
+                    }
+                }
+            }
+
+            return false;
         }
+
+        // internal use aonly, use write_extensions instead
+        template<typename T>
+        inline bool _write_extension(boost::json::object& extensions, const T* src, string_view member)
+        {
+            if (src->mPresent)
+            {
+                Value v;
+                if (write(*src, v))
+                {
+                    extensions[member] = v;
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        // Write all extensions to dst.extensions
+        // Usage:
+        //  write_extensions(dst,
+        //                   mUnlit, "KHR_materials_unlit",
+        //                   mPbrSpecularGlossiness, "KHR_materials_pbrSpecularGlossiness");
+        // returns true if any of the extensions are written
+        template<class... Types>
+        inline bool write_extensions(boost::json::object& dst, Types... args)
+        {
+            bool success = false;
+
+            boost::json::object extensions;
+            U32 count = sizeof...(args) - 1;
+
+            for (U32 i = 0; i < count; i += 2)
+            {
+                if (_write_extension(extensions, args...))
+                {
+                    success = true;
+                }
+            }
+
+            if (success)
+            {
+                dst["extensions"] = extensions;
+            }
+
+            return success;
+        }
+
+        // conditionally write a member to an object if the member
+        // is not the default value
+        template<typename T>
+        inline bool write(const T& src, string_view member, boost::json::object& dst, const T& default_value = T())
+        {
+            if (src != default_value)
+            {
+                return write_always(src, member, dst);
+            }
+            return false;
+        }
+
+        template<typename T>
+        inline bool write(const std::unordered_map<std::string, T>& src, string_view member, boost::json::object& dst, const std::unordered_map<std::string, T>& default_value = std::unordered_map<std::string, T>())
+        {
+            if (!src.empty())
+            {
+                Value v;
+                if (write<T>(src, v))
+                {
+                    dst[member] = v;
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        template<typename T>
+        inline bool write(const std::vector<T>& src, string_view member, boost::json::object& dst, const std::vector<T>& deafault_value = std::vector<T>())
+        {
+            if (!src.empty())
+            {
+                Value v;
+                if (write(src, v))
+                {
+                    dst[member] = v;
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        template<typename T>
+        inline bool copy(const Value& src, string_view member, T& dst)
+        {
+            if (src.is_object())
+            {
+                const boost::json::object& obj = src.as_object();
+                return copy(obj, member, dst);
+            }
+
+            return false;
+        }
+
+        // Accessor::ComponentType
+        template<>
+        inline bool copy(const Value& src, Accessor::ComponentType& dst)
+        {
+            if (src.is_int64())
+            {
+                dst = (Accessor::ComponentType)src.get_int64();
+                return true;
+            }
+            return false;
+        }
+
+        template<>
+        inline bool write(const Accessor::ComponentType& src, Value& dst)
+        {
+            dst = (S32)src;
+            return true;
+        }
+
+        //Primitive::Mode
+        template<>
+        inline bool copy(const Value& src, Primitive::Mode& dst)
+        {
+            if (src.is_int64())
+            {
+                dst = (Primitive::Mode)src.get_int64();
+                return true;
+            }
+            return false;
+        }
+
+        template<>
+        inline bool write(const Primitive::Mode& src, Value& dst)
+        {
+            dst = (S32)src;
+            return true;
+        }
+
+        // vec4
+        template<>
+        inline bool copy(const Value& src, vec4& dst)
+        {
+            if (src.is_array())
+            {
+                const boost::json::array& arr = src.as_array();
+                if (arr.size() == 4)
+                {
+                    vec4 v;
+                    std::error_code ec;
+
+                    v.x = arr[0].to_number<F32>(ec); if (ec) return false;
+                    v.y = arr[1].to_number<F32>(ec); if (ec) return false;
+                    v.z = arr[2].to_number<F32>(ec); if (ec) return false;
+                    v.w = arr[3].to_number<F32>(ec); if (ec) return false;
+
+                    dst = v;
+
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        template<>
+        inline bool write(const vec4& src, Value& dst)
+        {
+            dst = boost::json::array();
+            boost::json::array& arr = dst.get_array();
+            arr.resize(4);
+            arr[0] = src.x;
+            arr[1] = src.y;
+            arr[2] = src.z;
+            arr[3] = src.w;
+            return true;
+        }
+
+        // quat
+        template<>
+        inline bool copy(const Value& src, quat& dst)
+        {
+            if (src.is_array())
+            {
+                const boost::json::array& arr = src.as_array();
+                if (arr.size() == 4)
+                {
+                    std::error_code ec;
+                    dst.x = arr[0].to_number<F32>(ec); if (ec) return false;
+                    dst.y = arr[1].to_number<F32>(ec); if (ec) return false;
+                    dst.z = arr[2].to_number<F32>(ec); if (ec) return false;
+                    dst.w = arr[3].to_number<F32>(ec); if (ec) return false;
+
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        template<>
+        inline bool write(const quat& src, Value& dst)
+        {
+            dst = boost::json::array();
+            boost::json::array& arr = dst.get_array();
+            arr.resize(4);
+            arr[0] = src.x;
+            arr[1] = src.y;
+            arr[2] = src.z;
+            arr[3] = src.w;
+            return true;
+        }
+
+
+        // vec3
+        template<>
+        inline bool copy(const Value& src, vec3& dst)
+        {
+            if (src.is_array())
+            {
+                const boost::json::array& arr = src.as_array();
+                if (arr.size() == 3)
+                {
+                    std::error_code ec;
+                    vec3 t;
+                    t.x = arr[0].to_number<F32>(ec); if (ec) return false;
+                    t.y = arr[1].to_number<F32>(ec); if (ec) return false;
+                    t.z = arr[2].to_number<F32>(ec); if (ec) return false;
+
+                    dst = t;
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        template<>
+        inline bool write(const vec3& src, Value& dst)
+        {
+            dst = boost::json::array();
+            boost::json::array& arr = dst.as_array();
+            arr.resize(3);
+            arr[0] = src.x;
+            arr[1] = src.y;
+            arr[2] = src.z;
+            return true;
+        }
+
+        // vec2
+        template<>
+        inline bool copy(const Value& src, vec2& dst)
+        {
+            if (src.is_array())
+            {
+                const boost::json::array& arr = src.as_array();
+                if (arr.size() == 2)
+                {
+                    std::error_code ec;
+                    vec2 t;
+                    t.x = arr[0].to_number<F32>(ec); if (ec) return false;
+                    t.y = arr[1].to_number<F32>(ec); if (ec) return false;
+
+                    dst = t;
+                    return true;
+                }
+            }
+            return false;
+        }
+
+        template<>
+        inline bool write(const vec2& src, Value& dst)
+        {
+            dst = boost::json::array();
+            boost::json::array& arr = dst.as_array();
+            arr.resize(2);
+            arr[0] = src.x;
+            arr[1] = src.y;
+
+            return true;
+        }
+
+        // bool
+        template<>
+        inline bool copy(const Value& src, bool& dst)
+        {
+            if (src.is_bool())
+            {
+                dst = src.get_bool();
+                return true;
+            }
+            return false;
+        }
+
+        template<>
+        inline bool write(const bool& src, Value& dst)
+        {
+            dst = src;
+            return true;
+        }
+
+        // F32
+        template<>
+        inline bool copy(const Value& src, F32& dst)
+        {
+            std::error_code ec;
+            F32 t = src.to_number<F32>(ec); if (ec) return false;
+            dst = t;
+            return true;
+        }
+
+        template<>
+        inline bool write(const F32& src, Value& dst)
+        {
+            dst = src;
+            return true;
+        }
+
+
+        // U32
+        template<>
+        inline bool copy(const Value& src, U32& dst)
+        {
+            if (src.is_int64())
+            {
+                dst = src.get_int64();
+                return true;
+            }
+            return false;
+        }
+
+        template<>
+        inline bool write(const U32& src, Value& dst)
+        {
+            dst = src;
+            return true;
+        }
+
+        // F64
+        template<>
+        inline bool copy(const Value& src, F64& dst)
+        {
+            std::error_code ec;
+            F64 t = src.to_number<F64>(ec); if (ec) return false;
+            dst = t;
+            return true;
+        }
+
+        template<>
+        inline bool write(const F64& src, Value& dst)
+        {
+            dst = src;
+            return true;
+        }
+
+        // Accessor::Type
+        template<>
+        inline bool copy(const Value& src, Accessor::Type& dst)
+        {
+            if (src.is_string())
+            {
+                dst = gltf_type_to_enum(src.get_string().c_str());
+                return true;
+            }
+            return false;
+        }
+
+        template<>
+        inline bool write(const Accessor::Type& src, Value& dst)
+        {
+            dst = enum_to_gltf_type(src);
+            return true;
+        }
+
+        // S32
+        template<>
+        inline bool copy(const Value& src, S32& dst)
+        {
+            if (src.is_int64())
+            {
+                dst = src.get_int64();
+                return true;
+            }
+            return false;
+        }
+
+        template<>
+        inline bool write(const S32& src, Value& dst)
+        {
+            dst = src;
+            return true;
+        }
+
+
+        // std::string
+        template<>
+        inline bool copy(const Value& src, std::string& dst)
+        {
+            if (src.is_string())
+            {
+                dst = src.get_string().c_str();
+                return true;
+            }
+            return false;
+        }
+
+        template<>
+        inline bool write(const std::string& src, Value& dst)
+        {
+            dst = src;
+            return true;
+        }
+
+        // mat4
+        template<>
+        inline bool copy(const Value& src, mat4& dst)
+        {
+            if (src.is_array())
+            {
+                const boost::json::array& arr = src.get_array();
+                if (arr.size() == 16)
+                {
+                    // populate a temporary local in case
+                    // we hit an error in the middle of the array
+                    // (don't partially write a matrix)
+                    mat4 t;
+                    F32* p = glm::value_ptr(t);
+
+                    for (U32 i = 0; i < arr.size(); ++i)
+                    {
+                        std::error_code ec;
+                        p[i] = arr[i].to_number<F32>(ec);
+                        if (ec)
+                        {
+                            return false;
+                        }
+                    }
+
+                    dst = t;
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        template<>
+        inline bool write(const mat4& src, Value& dst)
+        {
+            dst = boost::json::array();
+            boost::json::array& arr = dst.get_array();
+            arr.resize(16);
+            const F32* p = glm::value_ptr(src);
+            for (U32 i = 0; i < 16; ++i)
+            {
+                arr[i] = p[i];
+            }
+            return true;
+        }
+
+        // Material::AlphaMode
+        template<>
+        inline bool copy(const Value& src, Material::AlphaMode& dst)
+        {
+            if (src.is_string())
+            {
+                dst = gltf_alpha_mode_to_enum(src.get_string().c_str());
+                return true;
+            }
+            return true;
+        }
+
+        template<>
+        inline bool write(const Material::AlphaMode& src, Value& dst)
+        {
+            dst = enum_to_gltf_alpha_mode(src);
+            return true;
+        }
+
+        //
+        // ========================================================================================================
+
     }
 }
 
+
+
+
diff --git a/indra/newview/gltf/common.h b/indra/newview/gltf/common.h
new file mode 100644
index 0000000000..4f660d7cfc
--- /dev/null
+++ b/indra/newview/gltf/common.h
@@ -0,0 +1,83 @@
+#pragma once
+
+/**
+ * @file common.h
+ * @brief LL GLTF Implementation
+ *
+ * $LicenseInfo:firstyear=2024&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2024, Linden Research, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ *
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+#define GLM_ENABLE_EXPERIMENTAL 1
+
+#include "glm/vec2.hpp"
+#include "glm/vec3.hpp"
+#include "glm/vec4.hpp"
+#include "glm/mat4x4.hpp"
+#include "glm/gtc/type_ptr.hpp"
+#include "glm/ext/quaternion_float.hpp"
+#include "glm/gtx/quaternion.hpp"
+#include "glm/gtx/matrix_decompose.hpp"
+#include <boost/json.hpp>
+
+// Common types and constants used in the GLTF implementation
+namespace LL
+{
+    namespace GLTF
+    {
+        using Value = boost::json::value;
+
+        using mat4 = glm::mat4;
+        using vec4 = glm::vec4;
+        using vec3 = glm::vec3;
+        using vec2 = glm::vec2;
+        using quat = glm::quat;
+
+        constexpr S32 LINEAR = 9729;
+        constexpr S32 NEAREST = 9728;
+        constexpr S32 NEAREST_MIPMAP_NEAREST = 9984;
+        constexpr S32 LINEAR_MIPMAP_NEAREST = 9985;
+        constexpr S32 NEAREST_MIPMAP_LINEAR = 9986;
+        constexpr S32 LINEAR_MIPMAP_LINEAR = 9987;
+        constexpr S32 CLAMP_TO_EDGE = 33071;
+        constexpr S32 MIRRORED_REPEAT = 33648;
+        constexpr S32 REPEAT = 10497;
+
+
+        class Asset;
+        class Material;
+        class Mesh;
+        class Node;
+        class Scene;
+        class Texture;
+        class Sampler;
+        class Image;
+        class Animation;
+        class Skin;
+        class Camera;
+        class Light;
+        class Primitive;
+        class Accessor;
+        class BufferView;
+        class Buffer;
+    }
+}
+
diff --git a/indra/newview/gltf/primitive.cpp b/indra/newview/gltf/primitive.cpp
index b57a0af18d..2280c7004e 100644
--- a/indra/newview/gltf/primitive.cpp
+++ b/indra/newview/gltf/primitive.cpp
@@ -9,7 +9,7 @@
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation;
- * version 2.1 of the License only. 
+ * version 2.1 of the License only.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -28,12 +28,295 @@
 
 #include "asset.h"
 #include "buffer_util.h"
+#include "../llviewershadermgr.h"
+
+#include "mikktspace/mikktspace.hh"
+
+#include "meshoptimizer/meshoptimizer.h"
 
-#include "../lltinygltfhelper.h"
 
 using namespace LL::GLTF;
+using namespace boost::json;
+
+
+// Mesh data useful for Mikktspace tangent generation (and flat normal generation)
+struct MikktMesh
+{
+    std::vector<LLVector3> p;       //positions
+    std::vector<LLVector3> n;       //normals
+    std::vector<LLVector4> t;       //tangents
+    std::vector<LLVector2> tc0;     //texcoords 0
+    std::vector<LLVector2> tc1;     //texcoords 1
+    std::vector<LLColor4U> c;       //colors
+    std::vector<LLVector4> w;       //weights
+    std::vector<U64> j;             //joints
+
+    // initialize from src primitive and make an unrolled triangle list
+    // returns false if the Primitive cannot be converted to a triangle list
+    bool copy(const Primitive* prim)
+    {
+        bool indexed = !prim->mIndexArray.empty();
+        size_t vert_count = indexed ? prim->mIndexArray.size() : prim->mPositions.size();
+
+        size_t triangle_count = 0;
+
+        if (prim->mMode == Primitive::Mode::TRIANGLE_STRIP ||
+            prim->mMode == Primitive::Mode::TRIANGLE_FAN)
+        {
+            triangle_count = vert_count - 2;
+        }
+        else if (prim->mMode == Primitive::Mode::TRIANGLES)
+        {
+            triangle_count = vert_count / 3;
+        }
+        else
+        {
+            LL_WARNS("GLTF") << "Unsupported primitive mode for conversion to triangles: " << (S32)prim->mMode << LL_ENDL;
+            return false;
+        }
+
+        vert_count = triangle_count * 3;
+        llassert(vert_count <= size_t(U32_MAX));  // triangle_count will also naturally be under the limit
+
+        p.resize(vert_count);
+        n.resize(vert_count);
+        tc0.resize(vert_count);
+        c.resize(vert_count);
+
+        bool has_normals = !prim->mNormals.empty();
+        if (has_normals)
+        {
+            n.resize(vert_count);
+        }
+        bool has_tangents = !prim->mTangents.empty();
+        if (has_tangents)
+        {
+            t.resize(vert_count);
+        }
+
+        bool rigged = !prim->mWeights.empty();
+        if (rigged)
+        {
+            w.resize(vert_count);
+            j.resize(vert_count);
+        }
+
+        bool multi_uv = !prim->mTexCoords1.empty();
+        if (multi_uv)
+        {
+            tc1.resize(vert_count);
+        }
+
+        for (U32 tri_idx = 0; tri_idx < U32(triangle_count); ++tri_idx)
+        {
+            U32 idx[3];
+
+            if (prim->mMode == Primitive::Mode::TRIANGLES)
+            {
+                idx[0] = tri_idx * 3;
+                idx[1] = tri_idx * 3 + 1;
+                idx[2] = tri_idx * 3 + 2;
+            }
+            else if (prim->mMode == Primitive::Mode::TRIANGLE_STRIP)
+            {
+                idx[0] = tri_idx;
+                idx[1] = tri_idx + 1;
+                idx[2] = tri_idx + 2;
+
+                if (tri_idx % 2 != 0)
+                {
+                    std::swap(idx[1], idx[2]);
+                }
+            }
+            else if (prim->mMode == Primitive::Mode::TRIANGLE_FAN)
+            {
+                idx[0] = 0;
+                idx[1] = tri_idx + 1;
+                idx[2] = tri_idx + 2;
+            }
+
+            if (indexed)
+            {
+                idx[0] = prim->mIndexArray[idx[0]];
+                idx[1] = prim->mIndexArray[idx[1]];
+                idx[2] = prim->mIndexArray[idx[2]];
+            }
+
+            for (U32 v = 0; v < 3; ++v)
+            {
+                U32 i = tri_idx * 3 + v;
+                p[i].set(prim->mPositions[idx[v]].getF32ptr());
+                tc0[i].set(prim->mTexCoords0[idx[v]]);
+                c[i] = prim->mColors[idx[v]];
+
+                if (multi_uv)
+                {
+                    tc1[i].set(prim->mTexCoords1[idx[v]]);
+                }
+
+                if (has_normals)
+                {
+                    n[i].set(prim->mNormals[idx[v]].getF32ptr());
+                }
+
+                if (rigged)
+                {
+                    w[i].set(prim->mWeights[idx[v]].getF32ptr());
+                    j[i] = prim->mJoints[idx[v]];
+                }
+            }
+        }
+
+        return true;
+    }
+
+    void genNormals()
+    {
+        size_t tri_count = p.size() / 3;
+        for (size_t i = 0; i < tri_count; ++i)
+        {
+            LLVector3 v0 = p[i * 3];
+            LLVector3 v1 = p[i * 3 + 1];
+            LLVector3 v2 = p[i * 3 + 2];
+
+            LLVector3 normal = (v1 - v0) % (v2 - v0);
+            normal.normalize();
+
+            n[i * 3] = normal;
+            n[i * 3 + 1] = normal;
+            n[i * 3 + 2] = normal;
+        }
+    }
+
+    void genTangents()
+    {
+        t.resize(p.size());
+        mikk::Mikktspace ctx(*this);
+        ctx.genTangSpace();
+    }
+
+    // write to target primitive as an indexed triangle list
+    // Only modifies runtime data, does not modify the original GLTF data
+    void write(Primitive* prim) const
+    {
+        //re-weld
+        std::vector<meshopt_Stream> mos =
+        {
+            { &p[0], sizeof(LLVector3), sizeof(LLVector3) },
+            { &n[0], sizeof(LLVector3), sizeof(LLVector3) },
+            { &t[0], sizeof(LLVector4), sizeof(LLVector4) },
+            { &tc0[0], sizeof(LLVector2), sizeof(LLVector2) },
+            { &c[0], sizeof(LLColor4U), sizeof(LLColor4U) }
+        };
+
+        if (!w.empty())
+        {
+            mos.push_back({ &w[0], sizeof(LLVector4), sizeof(LLVector4) });
+            mos.push_back({ &j[0], sizeof(U64), sizeof(U64) });
+        }
+
+        if (!tc1.empty())
+        {
+            mos.push_back({ &tc1[0], sizeof(LLVector2), sizeof(LLVector2) });
+        }
+
+        std::vector<U32> remap;
+        remap.resize(p.size());
+
+        size_t stream_count = mos.size();
+
+        size_t vert_count = meshopt_generateVertexRemapMulti(&remap[0], nullptr, p.size(), p.size(), mos.data(), stream_count);
+
+        prim->mTexCoords0.resize(vert_count);
+        prim->mNormals.resize(vert_count);
+        prim->mTangents.resize(vert_count);
+        prim->mPositions.resize(vert_count);
+        prim->mColors.resize(vert_count);
+        if (!w.empty())
+        {
+            prim->mWeights.resize(vert_count);
+            prim->mJoints.resize(vert_count);
+        }
+        if (!tc1.empty())
+                    {
+            prim->mTexCoords1.resize(vert_count);
+        }
+
+        prim->mIndexArray.resize(remap.size());
+
+        for (int i = 0; i < remap.size(); ++i)
+        {
+            U32 src_idx = i;
+            U32 dst_idx = remap[i];
+
+            prim->mIndexArray[i] = dst_idx;
+
+            prim->mPositions[dst_idx].load3(p[src_idx].mV);
+            prim->mNormals[dst_idx].load3(n[src_idx].mV);
+            prim->mTexCoords0[dst_idx] = tc0[src_idx];
+            prim->mTangents[dst_idx].loadua(t[src_idx].mV);
+            prim->mColors[dst_idx] = c[src_idx];
+
+            if (!w.empty())
+            {
+                prim->mWeights[dst_idx].loadua(w[src_idx].mV);
+                prim->mJoints[dst_idx] = j[src_idx];
+            }
+
+            if (!tc1.empty())
+            {
+                prim->mTexCoords1[dst_idx] = tc1[src_idx];
+            }
+        }
+
+        prim->mGLMode = LLRender::TRIANGLES;
+    }
+
+    uint32_t GetNumFaces()
+    {
+        return uint32_t(p.size()/3);
+    }
+
+    uint32_t GetNumVerticesOfFace(const uint32_t face_num)
+    {
+        return 3;
+    }
+
+    mikk::float3 GetPosition(const uint32_t face_num, const uint32_t vert_num)
+    {
+        F32* v = p[face_num * 3 + vert_num].mV;
+        return mikk::float3(v);
+    }
+
+    mikk::float3 GetTexCoord(const uint32_t face_num, const uint32_t vert_num)
+    {
+        F32* uv = tc0[face_num * 3 + vert_num].mV;
+        return mikk::float3(uv[0], 1.f-uv[1], 1.0f);
+    }
+
+    mikk::float3 GetNormal(const uint32_t face_num, const uint32_t vert_num)
+    {
+        F32* normal = n[face_num * 3 + vert_num].mV;
+        return mikk::float3(normal);
+    }
+
+    void SetTangentSpace(const uint32_t face_num, const uint32_t vert_num, mikk::float3 T, bool orientation)
+    {
+        S32 i = face_num * 3 + vert_num;
+        t[i].set(T.x, T.y, T.z, orientation ? 1.0f : -1.0f);
+    }
+};
+
+
+static void vertical_flip(std::vector<LLVector2>& texcoords)
+{
+    for (auto& tc : texcoords)
+    {
+        tc[1] = 1.f - tc[1];
+    }
+}
 
-void Primitive::allocateGLResources(Asset& asset)
+bool Primitive::prep(Asset& asset)
 {
     // allocate vertex buffer
     // We diverge from the intent of the GLTF format here to work with our existing render pipeline
@@ -66,7 +349,11 @@ void Primitive::allocateGLResources(Asset& asset)
         }
         else if (attribName == "TEXCOORD_0")
         {
-            copy(asset, accessor, mTexCoords);
+            copy(asset, accessor, mTexCoords0);
+        }
+        else if (attribName == "TEXCOORD_1")
+        {
+            copy(asset, accessor, mTexCoords1);
         }
         else if (attribName == "JOINTS_0")
         {
@@ -83,96 +370,205 @@ void Primitive::allocateGLResources(Asset& asset)
     {
         Accessor& accessor = asset.mAccessors[mIndices];
         copy(asset, accessor, mIndexArray);
-    }
 
-    U32 mask = ATTRIBUTE_MASK;
-    
-    if (!mWeights.empty())
-    {
-        mask |= LLVertexBuffer::MAP_WEIGHT4;
+        for (auto& idx : mIndexArray)
+        {
+            if (idx >= mPositions.size())
+            {
+                LL_WARNS("GLTF") << "Invalid index array" << LL_ENDL;
+                return false;
+            }
+        }
     }
 
-    mVertexBuffer = new LLVertexBuffer(mask);
-    mVertexBuffer->allocateBuffer(mPositions.size(), mIndexArray.size()*2); // double the size of the index buffer for 32-bit indices
-
-    mVertexBuffer->setBuffer();
-    mVertexBuffer->setPositionData(mPositions.data());
+    U32 mask = LLVertexBuffer::MAP_VERTEX;
 
-    if (!mIndexArray.empty())
+    if (!mWeights.empty())
     {
-        mVertexBuffer->setIndexData(mIndexArray.data());
+        mask |= LLVertexBuffer::MAP_WEIGHT4;
+        mask |= LLVertexBuffer::MAP_JOINT;
     }
 
-    if (mTexCoords.empty())
+    if (mTexCoords0.empty())
     {
-        mTexCoords.resize(mPositions.size());
+        mTexCoords0.resize(mPositions.size());
     }
 
-    // flip texcoord y, upload, then flip back (keep the off-spec data in vram only)
-    for (auto& tc : mTexCoords)
-    {
-        tc[1] = 1.f - tc[1];
-    }
-    mVertexBuffer->setTexCoordData(mTexCoords.data());
+    mask |= LLVertexBuffer::MAP_TEXCOORD0;
 
-    for (auto& tc : mTexCoords)
+    if (!mTexCoords1.empty())
     {
-        tc[1] = 1.f - tc[1];
+        mask |= LLVertexBuffer::MAP_TEXCOORD1;
     }
 
     if (mColors.empty())
     {
         mColors.resize(mPositions.size(), LLColor4U::white);
     }
-    
+
+    mShaderVariant = 0;
+
+    // TODO: support colorless vertex buffers
+    mask |= LLVertexBuffer::MAP_COLOR;
+
+    bool unlit = false;
+
     // bake material basecolor into color array
     if (mMaterial != INVALID_INDEX)
     {
         const Material& material = asset.mMaterials[mMaterial];
-        LLColor4 baseColor = material.mMaterial->mBaseColor;
+        LLColor4 baseColor(glm::value_ptr(material.mPbrMetallicRoughness.mBaseColorFactor));
         for (auto& dst : mColors)
         {
             dst = LLColor4U(baseColor * LLColor4(dst));
         }
+
+        if (material.mUnlit.mPresent)
+        { // material uses KHR_materials_unlit
+            mShaderVariant |= LLGLSLShader::GLTFVariant::UNLIT;
+            unlit = true;
+        }
+
+        if (material.isMultiUV())
+        {
+            mShaderVariant |= LLGLSLShader::GLTFVariant::MULTI_UV;
+        }
     }
 
-    mVertexBuffer->setColorData(mColors.data());
+    if (mNormals.empty() && !unlit)
+    {
+        mTangents.clear();
+
+        if (mMode == Mode::POINTS || mMode == Mode::LINES || mMode == Mode::LINE_LOOP || mMode == Mode::LINE_STRIP)
+        { //no normals and no surfaces, this primitive is unlit
+            mTangents.clear();
+            mShaderVariant |= LLGLSLShader::GLTFVariant::UNLIT;
+            unlit = true;
+        }
+        else
+        {
+            // unroll into non-indexed array of flat shaded triangles
+            MikktMesh data;
+            if (!data.copy(this))
+            {
+                return false;
+            }
+
+            data.genNormals();
+            data.genTangents();
+            data.write(this);
+        }
+    }
 
-    if (mNormals.empty())
+    if (mTangents.empty() && !unlit)
+    { // NOTE: must be done last because tangent generation rewrites the other arrays
+        // adapted from usage of Mikktspace in llvolume.cpp
+        if (mMode == Mode::POINTS || mMode == Mode::LINES || mMode == Mode::LINE_LOOP || mMode == Mode::LINE_STRIP)
+        {
+            // for points and lines, just make sure tangent is perpendicular to normal
+            mTangents.resize(mNormals.size());
+            LLVector4a up(0.f, 0.f, 1.f, 0.f);
+            LLVector4a left(1.f, 0.f, 0.f, 0.f);
+            for (U32 i = 0; i < mNormals.size(); ++i)
+            {
+                if (fabsf(mNormals[i].getF32ptr()[2]) < 0.999f)
+                {
+                    mTangents[i] = up.cross3(mNormals[i]);
+                }
+                else
+                {
+                    mTangents[i] = left.cross3(mNormals[i]);
+                }
+
+                mTangents[i].getF32ptr()[3] = 1.f;
+            }
+        }
+        else
+        {
+            MikktMesh data;
+            if (!data.copy(this))
+            {
+                return false;
+            }
+
+            data.genTangents();
+            data.write(this);
+        }
+    }
+
+    if (!mNormals.empty())
     {
-        mNormals.resize(mPositions.size(), LLVector4a(0, 0, 1, 0));
+        mask |= LLVertexBuffer::MAP_NORMAL;
     }
-    
-    mVertexBuffer->setNormalData(mNormals.data());
 
-    if (mTangents.empty())
+    if (!mTangents.empty())
     {
-        // TODO: generate tangents if needed
-        mTangents.resize(mPositions.size(), LLVector4a(1, 0, 0, 1));
+        mask |= LLVertexBuffer::MAP_TANGENT;
     }
 
-    mVertexBuffer->setTangentData(mTangents.data());
+    if (LLGLSLShader::sCurBoundShaderPtr == nullptr)
+    { // make sure a shader is bound to satisfy mVertexBuffer->setBuffer
+        gDebugProgram.bind();
+    }
+
+    mVertexBuffer = new LLVertexBuffer(mask);
+    // we store these buffer sizes as S32 elsewhere
+    llassert(mPositions.size() <= size_t(S32_MAX));
+    llassert(mIndexArray.size() <= size_t(S32_MAX / 2));
+    mVertexBuffer->allocateBuffer(U32(mPositions.size()), U32(mIndexArray.size() * 2)); // double the size of the index buffer for 32-bit indices
+
+    mVertexBuffer->setBuffer();
+    mVertexBuffer->setPositionData(mPositions.data());
+    mVertexBuffer->setColorData(mColors.data());
+
+    if (!mNormals.empty())
+    {
+        mVertexBuffer->setNormalData(mNormals.data());
+    }
+    if (!mTangents.empty())
+    {
+        mVertexBuffer->setTangentData(mTangents.data());
+    }
 
     if (!mWeights.empty())
     {
-        std::vector<LLVector4a> weight_data;
-        weight_data.resize(mWeights.size());
+        mShaderVariant |= LLGLSLShader::GLTFVariant::RIGGED;
+        mVertexBuffer->setWeight4Data(mWeights.data());
+        mVertexBuffer->setJointData(mJoints.data());
+    }
+
+    // flip texcoord y, upload, then flip back (keep the off-spec data in vram only)
+    vertical_flip(mTexCoords0);
+    mVertexBuffer->setTexCoord0Data(mTexCoords0.data());
+    vertical_flip(mTexCoords0);
+
+    if (!mTexCoords1.empty())
+    {
+        vertical_flip(mTexCoords1);
+        mVertexBuffer->setTexCoord1Data(mTexCoords1.data());
+        vertical_flip(mTexCoords1);
+    }
 
-        F32 max_weight = 1.f - FLT_EPSILON*100.f;
-        LLVector4a maxw(max_weight, max_weight, max_weight, max_weight);
-        for (U32 i = 0; i < mWeights.size(); ++i)
-        {
-            LLVector4a& w = weight_data[i];
-            w.setMin(mWeights[i], maxw);
-            w.add(mJoints[i]);
-        };
 
-        mVertexBuffer->setWeight4Data(weight_data.data());
+    if (!mIndexArray.empty())
+    {
+        mVertexBuffer->setIndexData(mIndexArray.data());
     }
-    
+
     createOctree();
-    
+
     mVertexBuffer->unbind();
+
+    if (mMaterial != INVALID_INDEX)
+    {
+        Material& material = asset.mMaterials[mMaterial];
+        if (material.mAlphaMode == Material::AlphaMode::BLEND)
+        {
+            mShaderVariant |= LLGLSLShader::GLTFVariant::ALPHA_BLEND;
+        }
+    }
+
+    return true;
 }
 
 void initOctreeTriangle(LLVolumeTriangle* tri, F32 scaler, S32 i0, S32 i1, S32 i2, const LLVector4a& v0, const LLVector4a& v1, const LLVector4a& v2)
@@ -218,7 +614,7 @@ void Primitive::createOctree()
 
     F32 scaler = 0.25f;
 
-    if (mMode == TINYGLTF_MODE_TRIANGLES)
+    if (mMode == Mode::TRIANGLES)
     {
         const U32 num_triangles = mVertexBuffer->getNumIndices() / 3;
         // Initialize all the triangles we need
@@ -235,14 +631,14 @@ void Primitive::createOctree()
             const LLVector4a& v0 = mPositions[i0];
             const LLVector4a& v1 = mPositions[i1];
             const LLVector4a& v2 = mPositions[i2];
-            
+
             initOctreeTriangle(tri, scaler, i0, i1, i2, v0, v1, v2);
-            
+
             //insert
             mOctree->insert(tri);
         }
     }
-    else if (mMode == TINYGLTF_MODE_TRIANGLE_STRIP)
+    else if (mMode == Mode::TRIANGLE_STRIP)
     {
         const U32 num_triangles = mVertexBuffer->getNumIndices() - 2;
         // Initialize all the triangles we need
@@ -266,7 +662,7 @@ void Primitive::createOctree()
             mOctree->insert(tri);
         }
     }
-    else if (mMode == TINYGLTF_MODE_TRIANGLE_FAN)
+    else if (mMode == Mode::TRIANGLE_FAN)
     {
         const U32 num_triangles = mVertexBuffer->getNumIndices() - 2;
         // Initialize all the triangles we need
@@ -290,14 +686,14 @@ void Primitive::createOctree()
             mOctree->insert(tri);
         }
     }
-    else if (mMode == TINYGLTF_MODE_POINTS ||
-            mMode == TINYGLTF_MODE_LINE ||
-        mMode == TINYGLTF_MODE_LINE_LOOP ||
-        mMode == TINYGLTF_MODE_LINE_STRIP)
+    else if (mMode == Mode::POINTS ||
+            mMode == Mode::LINES ||
+        mMode == Mode::LINE_LOOP ||
+        mMode == Mode::LINE_STRIP)
     {
         // nothing to do, no volume... maybe add some collision geometry around these primitive types?
     }
-    
+
     else
     {
         LL_ERRS() << "Unsupported Primitive mode" << LL_ENDL;
@@ -327,13 +723,13 @@ const LLVolumeTriangle* Primitive::lineSegmentIntersect(const LLVector4a& start,
     //create a proxy LLVolumeFace for the raycast
     LLVolumeFace face;
     face.mPositions = mPositions.data();
-    face.mTexCoords = mTexCoords.data();
+    face.mTexCoords = mTexCoords0.data();
     face.mNormals = mNormals.data();
     face.mTangents = mTangents.data();
     face.mIndices = nullptr; // unreferenced
 
-    face.mNumIndices = mIndexArray.size();
-    face.mNumVertices = mPositions.size();
+    face.mNumIndices = S32(mIndexArray.size());
+    face.mNumVertices = S32(mPositions.size());
 
     LLOctreeTriangleRayIntersect intersect(start, dir, &face, &closest_t, intersection, tex_coord, normal, tangent_out);
     intersect.traverse(mOctree);
@@ -351,50 +747,48 @@ Primitive::~Primitive()
     mOctree = nullptr;
 }
 
-
-const Primitive& Primitive::operator=(const tinygltf::Primitive& src)
+LLRender::eGeomModes gltf_mode_to_gl_mode(Primitive::Mode mode)
 {
-    // load material
-    mMaterial = src.material;
-
-    // load mode
-    mMode = src.mode;
-
-    // load indices
-    mIndices = src.indices;
-
-    // load attributes
-    for (auto& it : src.attributes)
-    {
-        mAttributes[it.first] = it.second;
-    }
-
-    switch (mMode)
-    {
-    case TINYGLTF_MODE_POINTS:
-        mGLMode = LLRender::POINTS;
-        break;
-    case TINYGLTF_MODE_LINE:
-        mGLMode = LLRender::LINES;
-        break;
-    case TINYGLTF_MODE_LINE_LOOP:
-        mGLMode = LLRender::LINE_LOOP;
-        break;
-    case TINYGLTF_MODE_LINE_STRIP:
-        mGLMode = LLRender::LINE_STRIP;
-        break;
-    case TINYGLTF_MODE_TRIANGLES:
-        mGLMode = LLRender::TRIANGLES;
-        break;
-    case TINYGLTF_MODE_TRIANGLE_STRIP:
-        mGLMode = LLRender::TRIANGLE_STRIP;
-        break;
-    case TINYGLTF_MODE_TRIANGLE_FAN:
-        mGLMode = LLRender::TRIANGLE_FAN;
-        break;
+    switch (mode)
+    {
+    case Primitive::Mode::POINTS:
+        return LLRender::POINTS;
+    case Primitive::Mode::LINES:
+        return LLRender::LINES;
+    case Primitive::Mode::LINE_LOOP:
+        return LLRender::LINE_LOOP;
+    case Primitive::Mode::LINE_STRIP:
+        return LLRender::LINE_STRIP;
+    case Primitive::Mode::TRIANGLES:
+        return LLRender::TRIANGLES;
+    case Primitive::Mode::TRIANGLE_STRIP:
+        return LLRender::TRIANGLE_STRIP;
+    case Primitive::Mode::TRIANGLE_FAN:
+        return LLRender::TRIANGLE_FAN;
     default:
-        mGLMode = GL_TRIANGLES;
+        return LLRender::TRIANGLES;
     }
+}
+
+void Primitive::serialize(boost::json::object& dst) const
+{
+    write(mMaterial, "material", dst, -1);
+    write(mMode, "mode", dst, Primitive::Mode::TRIANGLES);
+    write(mIndices, "indices", dst, INVALID_INDEX);
+    write(mAttributes, "attributes", dst);
+}
 
+const Primitive& Primitive::operator=(const Value& src)
+{
+    if (src.is_object())
+    {
+        copy(src, "material", mMaterial);
+        copy(src, "mode", mMode);
+        copy(src, "indices", mIndices);
+        copy(src, "attributes", mAttributes);
+
+        mGLMode = gltf_mode_to_gl_mode(mMode);
+    }
     return *this;
 }
+
diff --git a/indra/newview/gltf/primitive.h b/indra/newview/gltf/primitive.h
index 07e8e7deb2..7cc05cf831 100644
--- a/indra/newview/gltf/primitive.h
+++ b/indra/newview/gltf/primitive.h
@@ -28,35 +28,42 @@
 
 #include "llvertexbuffer.h"
 #include "llvolumeoctree.h"
+#include "boost/json.hpp"
 
 // LL GLTF Implementation
 namespace LL
 {
     namespace GLTF
     {
+        using Value = boost::json::value;
         class Asset;
 
-        constexpr U32 ATTRIBUTE_MASK =
-            LLVertexBuffer::MAP_VERTEX |
-            LLVertexBuffer::MAP_NORMAL |
-            LLVertexBuffer::MAP_TEXCOORD0 |
-            LLVertexBuffer::MAP_TANGENT |
-            LLVertexBuffer::MAP_COLOR;
-
         class Primitive
         {
         public:
+            enum class Mode : U8
+            {
+                POINTS,
+                LINES,
+                LINE_LOOP,
+                LINE_STRIP,
+                TRIANGLES,
+                TRIANGLE_STRIP,
+                TRIANGLE_FAN
+            };
+
             ~Primitive();
 
             // GPU copy of mesh data
             LLPointer<LLVertexBuffer> mVertexBuffer;
 
-            // CPU copy of mesh data
-            std::vector<LLVector2> mTexCoords;
+            // CPU copy of mesh data, keep these as LLVector types for compatibility with raycasting code
+            std::vector<LLVector2> mTexCoords0;
+            std::vector<LLVector2> mTexCoords1;
             std::vector<LLVector4a> mNormals;
             std::vector<LLVector4a> mTangents;
             std::vector<LLVector4a> mPositions;
-            std::vector<LLVector4a> mJoints;
+            std::vector<U64> mJoints;
             std::vector<LLVector4a> mWeights;
             std::vector<LLColor4U> mColors;
             std::vector<U32> mIndexArray;
@@ -64,18 +71,22 @@ namespace LL
             // raycast acceleration structure
             LLPointer<LLVolumeOctree> mOctree;
             std::vector<LLVolumeTriangle> mOctreeTriangles;
-            
+
             S32 mMaterial = -1;
-            U32 mMode = TINYGLTF_MODE_TRIANGLES; // default to triangles
-            U32 mGLMode = LLRender::TRIANGLES;
+            Mode mMode = Mode::TRIANGLES; // default to triangles
+            LLRender::eGeomModes mGLMode = LLRender::TRIANGLES; // for use with LLRender
             S32 mIndices = -1;
-            std::unordered_map<std::string, int> mAttributes;
+
+            // shader variant according to LLGLSLShader::GLTFVariant flags
+            U8 mShaderVariant = 0;
+
+            std::unordered_map<std::string, S32> mAttributes;
 
             // create octree based on vertex buffer
             // must be called before buffer is unmapped and after buffer is populated with good data
             void createOctree();
 
-            //get the LLVolumeTriangle that intersects with the given line segment at the point 
+            //get the LLVolumeTriangle that intersects with the given line segment at the point
             //closest to start.  Moves end to the point of intersection.  Returns nullptr if no intersection.
             //Line segment must be in the same coordinate frame as this Primitive
             const LLVolumeTriangle* lineSegmentIntersect(const LLVector4a& start, const LLVector4a& end,
@@ -84,10 +95,11 @@ namespace LL
                 LLVector4a* normal = NULL,               // return the surface normal at the intersection point
                 LLVector4a* tangent = NULL             // return the surface tangent at the intersection point
             );
-            
-            const Primitive& operator=(const tinygltf::Primitive& src);
 
-            void allocateGLResources(Asset& asset);
+            void serialize(boost::json::object& obj) const;
+            const Primitive& operator=(const Value& src);
+
+            bool prep(Asset& asset);
         };
     }
 }