Merge branch 'main' of github.com:secondlife/viewer into lua-bradfix

to pick up Featurettes promotion + Brad's GitHub Windows build workaround.

9 files changed, 2452 insertions, 0 deletions

diff --git a/indra/newview/gltf/accessor.cpp b/indra/newview/gltf/accessor.cpp
new file mode 100644
index 0000000000..55d36b7a32
--- /dev/null
+++ b/indra/newview/gltf/accessor.cpp
@@ -0,0 +1,66 @@
+/**
+ * @file accessor.cpp
+ * @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
+ * $/LicenseInfo$
+ */
+
+#include "../llviewerprecompiledheaders.h"
+
+#include "asset.h"
+
+using namespace LL::GLTF;
+
+const Buffer& Buffer::operator=(const tinygltf::Buffer& src)
+{
+    mData = src.data;
+    mName = src.name;
+    mUri = src.uri;
+    return *this;
+}
+
+const BufferView& BufferView::operator=(const tinygltf::BufferView& src)
+{
+    mBuffer = src.buffer;
+    mByteLength = src.byteLength;
+    mByteOffset = src.byteOffset;
+    mByteStride = src.byteStride;
+    mTarget = src.target;
+    mName = src.name;
+    return *this;
+}
+
+const Accessor& Accessor::operator=(const tinygltf::Accessor& src)
+{
+    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;
+
+    return *this;
+}
+
diff --git a/indra/newview/gltf/accessor.h b/indra/newview/gltf/accessor.h
new file mode 100644
index 0000000000..9b8265d8da
--- /dev/null
+++ b/indra/newview/gltf/accessor.h
@@ -0,0 +1,95 @@
+#pragma once
+
+/**
+ * @file asset.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
+ * $/LicenseInfo$
+ */
+
+#include "../lltinygltfhelper.h"
+#include "llstrider.h"
+
+// LL GLTF Implementation
+namespace LL
+{
+    namespace GLTF
+    {
+        class Asset;
+
+        constexpr S32 INVALID_INDEX = -1;
+
+        class Buffer
+        {
+        public:
+            std::vector<U8> mData;
+            std::string mName;
+            std::string mUri;
+
+            const Buffer& operator=(const tinygltf::Buffer& src);
+        };
+
+        class BufferView
+        {
+        public:
+            S32 mBuffer = INVALID_INDEX;
+            S32 mByteLength;
+            S32 mByteOffset;
+            S32 mByteStride;
+            S32 mTarget;
+            S32 mComponentType;
+
+            std::string mName;
+
+            const BufferView& operator=(const tinygltf::BufferView& src);
+            
+        };
+        
+        class Accessor
+        {
+        public:
+            S32 mBufferView = INVALID_INDEX;
+            S32 mByteOffset;
+            S32 mComponentType;
+            S32 mCount;
+            std::vector<double> mMax;
+            std::vector<double> mMin;
+
+            enum class Type : S32
+            {
+                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
+            };
+
+            S32 mType;
+            bool mNormalized;
+            std::string mName;
+
+            const Accessor& operator=(const tinygltf::Accessor& src);
+        };
+    }
+}
diff --git a/indra/newview/gltf/animation.cpp b/indra/newview/gltf/animation.cpp
new file mode 100644
index 0000000000..da6d02b356
--- /dev/null
+++ b/indra/newview/gltf/animation.cpp
@@ -0,0 +1,287 @@
+/**
+ * @file animation.cpp
+ * @brief LL GLTF Animation 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
+ * $/LicenseInfo$
+ */
+
+#include "../llviewerprecompiledheaders.h"
+
+#include "asset.h"
+#include "buffer_util.h"
+
+using namespace LL::GLTF;
+
+void Animation::allocateGLResources(Asset& asset)
+{
+    if (!mSamplers.empty())
+    {
+        mMinTime = FLT_MAX;
+        mMaxTime = -FLT_MAX;
+        for (auto& sampler : mSamplers)
+        {
+            sampler.allocateGLResources(asset);
+            mMinTime = llmin(sampler.mMinTime, mMinTime);
+            mMaxTime = llmax(sampler.mMaxTime, mMaxTime);
+        }
+    }
+    else
+    {
+        mMinTime = mMaxTime = 0.f;
+    }
+
+    for (auto& channel : mRotationChannels)
+    {
+        channel.allocateGLResources(asset, mSamplers[channel.mSampler]);
+    }
+
+    for (auto& channel : mTranslationChannels)
+    {
+        channel.allocateGLResources(asset, mSamplers[channel.mSampler]);
+    }
+}
+
+void Animation::update(Asset& asset, F32 dt)
+{
+    mTime += dt;
+
+    apply(asset, mTime);
+}
+
+void Animation::apply(Asset& asset, float time)
+{
+    // convert time to animation loop time
+    time = fmod(time, mMaxTime - mMinTime) + mMinTime;
+
+    // apply each channel
+    for (auto& channel : mRotationChannels)
+    {
+        channel.apply(asset, mSamplers[channel.mSampler], time);
+    }
+
+    for (auto& channel : mTranslationChannels)
+    {
+        channel.apply(asset, mSamplers[channel.mSampler], time);
+    }
+};
+
+
+void Animation::Sampler::allocateGLResources(Asset& asset)
+{
+    Accessor& accessor = asset.mAccessors[mInput];
+    mMinTime = accessor.mMin[0];
+    mMaxTime = accessor.mMax[0];
+
+    mFrameTimes.resize(accessor.mCount);
+
+    LLStrider<F32> frame_times = mFrameTimes.data();
+    copy(asset, accessor, frame_times);
+}
+
+void Animation::Sampler::getFrameInfo(Asset& asset, F32 time, U32& frameIndex, F32& t)
+{
+    if (time < mMinTime)
+    {
+        frameIndex = 0;
+        t = 0.0f;
+        return;
+    }
+
+    if (mFrameTimes.size() > 1)
+    {
+        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++)
+        {
+            if (time >= mFrameTimes[i] && time < mFrameTimes[i + 1])
+            {
+                frameIndex = i;
+                t = (time - mFrameTimes[i]) / (mFrameTimes[i + 1] - mFrameTimes[i]);
+                return;
+            }
+        }
+    }
+    else
+    {
+        frameIndex = 0;
+        t = 0.0f;
+    }
+}
+
+void Animation::RotationChannel::allocateGLResources(Asset& asset, Animation::Sampler& sampler)
+{
+    Accessor& accessor = asset.mAccessors[sampler.mOutput];
+
+    copy(asset, accessor, mRotations);
+}
+
+void Animation::RotationChannel::apply(Asset& asset, Sampler& sampler, F32 time)
+{
+    U32 frameIndex;
+    F32 t;
+
+    Node& node = asset.mNodes[mTarget.mNode];
+
+    sampler.getFrameInfo(asset, time, frameIndex, t);
+
+    if (sampler.mFrameTimes.size() == 1)
+    {
+        node.setRotation(mRotations[0]);
+    }
+    else
+    {
+        // interpolate
+        LLQuaternion q0(mRotations[frameIndex].get_value());
+        LLQuaternion q1(mRotations[frameIndex + 1].get_value());
+
+        LLQuaternion qf = slerp(t, q0, q1);
+
+        qf.normalize();
+        node.setRotation(glh::quaternionf(qf.mQ));
+    }
+}
+
+void Animation::TranslationChannel::allocateGLResources(Asset& asset, Animation::Sampler& sampler)
+{
+    Accessor& accessor = asset.mAccessors[sampler.mOutput];
+
+    copy(asset, accessor, mTranslations);
+}
+
+void Animation::TranslationChannel::apply(Asset& asset, Sampler& sampler, F32 time)
+{
+    U32 frameIndex;
+    F32 t;
+
+    Node& node = asset.mNodes[mTarget.mNode];
+
+    sampler.getFrameInfo(asset, time, frameIndex, t);
+
+    if (sampler.mFrameTimes.size() == 1)
+    {
+        node.setTranslation(mTranslations[0]);
+    }
+    else
+    {
+        // interpolate
+        const glh::vec3f& v0 = mTranslations[frameIndex];
+        const glh::vec3f& v1 = mTranslations[frameIndex + 1];
+
+        glh::vec3f vf = v0 + t * (v1 - v0);
+
+        node.setTranslation(vf);
+    }
+}
+
+void Animation::ScaleChannel::allocateGLResources(Asset& asset, Animation::Sampler& sampler)
+{
+    Accessor& accessor = asset.mAccessors[sampler.mOutput];
+
+    copy(asset, accessor, mScales);
+}
+
+void Animation::ScaleChannel::apply(Asset& asset, Sampler& sampler, F32 time)
+{
+    U32 frameIndex;
+    F32 t;
+
+    Node& node = asset.mNodes[mTarget.mNode];
+
+    sampler.getFrameInfo(asset, time, frameIndex, t);
+
+    if (sampler.mFrameTimes.size() == 1)
+    {
+        node.setScale(mScales[0]);
+    }
+    else
+    {
+        // interpolate
+        const glh::vec3f& v0 = mScales[frameIndex];
+        const glh::vec3f& v1 = mScales[frameIndex + 1];
+
+        glh::vec3f vf = v0 + t * (v1 - v0);
+
+        node.setScale(vf);
+    }
+}
+
+const Animation& Animation::operator=(const tinygltf::Animation& src)
+{
+    mName = src.name;
+
+    mSamplers.resize(src.samplers.size());
+    for (U32 i = 0; i < src.samplers.size(); ++i)
+    {
+        mSamplers[i] = src.samplers[i];
+    }
+
+    for (U32 i = 0; i < src.channels.size(); ++i)
+    {
+        if (src.channels[i].target_path == "rotation")
+        {
+            mRotationChannels.push_back(RotationChannel());
+            mRotationChannels.back() = src.channels[i];
+        }
+
+        if (src.channels[i].target_path == "translation")
+        {
+            mTranslationChannels.push_back(TranslationChannel());
+            mTranslationChannels.back() = src.channels[i];
+        }
+
+        if (src.channels[i].target_path == "scale")
+        {
+            mScaleChannels.push_back(ScaleChannel());
+            mScaleChannels.back() = src.channels[i];
+        }
+    }
+
+    return *this;
+}
+
+void Skin::allocateGLResources(Asset& asset)
+{
+    if (mInverseBindMatrices != INVALID_INDEX)
+    {
+        Accessor& accessor = asset.mAccessors[mInverseBindMatrices];
+        copy(asset, accessor, mInverseBindMatricesData);
+    }
+}
+
+const Skin& Skin::operator=(const tinygltf::Skin& src)
+{
+    mName = src.name;
+    mSkeleton = src.skeleton;
+    mInverseBindMatrices = src.inverseBindMatrices;
+    mJoints = src.joints;
+
+    return *this;
+}
+
diff --git a/indra/newview/gltf/animation.h b/indra/newview/gltf/animation.h
new file mode 100644
index 0000000000..869eae963a
--- /dev/null
+++ b/indra/newview/gltf/animation.h
@@ -0,0 +1,181 @@
+#pragma once
+
+/**
+ * @file animation.h
+ * @brief LL GLTF Animation 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
+ * $/LicenseInfo$
+ */
+
+#include "accessor.h"
+
+// LL GLTF Implementation
+namespace LL
+{
+    namespace GLTF
+    {
+        class Asset;
+
+        class Animation
+        {
+        public:
+            class Sampler
+            {
+            public:
+                std::vector<F32> mFrameTimes;
+
+                F32 mMinTime = -FLT_MAX;
+                F32 mMaxTime = FLT_MAX;
+
+                S32 mInput = INVALID_INDEX;
+                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;
+
+                    return *this;
+                }
+
+                // get the frame index and time for the specified time
+                // asset -- the asset to reference for Accessors
+                // time -- the animation time to get the frame info for
+                // frameIndex -- index of the closest frame that precedes the specified time
+                // t - interpolant value between the frameIndex and the next frame
+                void getFrameInfo(Asset& asset, F32 time, U32& frameIndex, F32& t);
+            };
+
+            class Channel
+            {
+            public:
+                class Target
+                {
+                public:
+                    S32 mNode = INVALID_INDEX;
+                    std::string mPath;
+                };
+
+                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;
+                }
+
+            };
+
+            class RotationChannel : public Channel
+            {
+            public:
+                std::vector<glh::quaternionf> mRotations;
+
+                const RotationChannel& operator=(const tinygltf::AnimationChannel& src)
+                {
+                    Channel::operator=(src);
+                    return *this;
+                }
+
+                // prepare data needed for rendering
+                // asset -- asset to reference for Accessors
+                // sampler -- Sampler associated with this channel
+                void allocateGLResources(Asset& asset, Sampler& sampler);
+
+                void apply(Asset& asset, Sampler& sampler, F32 time);
+            };
+
+            class TranslationChannel : public Channel
+            {
+            public:
+                std::vector<glh::vec3f> mTranslations;
+
+                const TranslationChannel& operator=(const tinygltf::AnimationChannel& src)
+                {
+                    Channel::operator=(src);
+                    return *this;
+                }
+
+                // prepare data needed for rendering
+                // asset -- asset to reference for Accessors
+                // sampler -- Sampler associated with this channel
+                void allocateGLResources(Asset& asset, Sampler& sampler);
+
+                void apply(Asset& asset, Sampler& sampler, F32 time);
+            };
+
+            class ScaleChannel : public Channel
+            {
+            public:
+                std::vector<glh::vec3f> mScales;
+
+                const ScaleChannel& operator=(const tinygltf::AnimationChannel& src)
+                {
+                    Channel::operator=(src);
+                    return *this;
+                }
+
+                // prepare data needed for rendering
+                // asset -- asset to reference for Accessors
+                // sampler -- Sampler associated with this channel
+                void allocateGLResources(Asset& asset, Sampler& sampler);
+
+                void apply(Asset& asset, Sampler& sampler, F32 time);
+            };
+
+            std::string mName;
+            std::vector<Sampler> mSamplers;
+
+            // 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;
+
+            std::vector<RotationChannel> mRotationChannels;
+            std::vector<TranslationChannel> mTranslationChannels;
+            std::vector<ScaleChannel> mScaleChannels;
+
+            const Animation& operator=(const tinygltf::Animation& src);
+            
+            void allocateGLResources(Asset& asset);
+
+            void update(Asset& asset, float dt);
+
+            // apply this animation at the specified time
+            void apply(Asset& asset, F32 time);
+        };
+
+    }
+}
diff --git a/indra/newview/gltf/asset.cpp b/indra/newview/gltf/asset.cpp
new file mode 100644
index 0000000000..313e82bf01
--- /dev/null
+++ b/indra/newview/gltf/asset.cpp
@@ -0,0 +1,664 @@
+/**
+ * @file asset.cpp
+ * @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
+ * $/LicenseInfo$
+ */
+
+#include "../llviewerprecompiledheaders.h"
+
+#include "asset.h"
+#include "llvolumeoctree.h"
+#include "../llviewershadermgr.h"
+#include "../llviewercontrol.h"
+
+using namespace LL::GLTF;
+
+void Scene::updateTransforms(Asset& asset)
+{
+    LLMatrix4a identity;
+    identity.setIdentity();
+    for (auto& nodeIndex : mNodes)
+    {
+        Node& node = asset.mNodes[nodeIndex];
+        node.updateTransforms(asset, identity);
+    }
+}
+
+void Scene::updateRenderTransforms(Asset& asset, const LLMatrix4a& modelview)
+{
+    for (auto& nodeIndex : mNodes)
+    {
+        Node& node = asset.mNodes[nodeIndex];
+        node.updateRenderTransforms(asset, modelview);
+    }
+}
+
+void Node::updateRenderTransforms(Asset& asset, const LLMatrix4a& modelview)
+{
+    matMul(mMatrix, modelview, mRenderMatrix);
+
+    for (auto& childIndex : mChildren)
+    {
+        Node& child = asset.mNodes[childIndex];
+        child.updateRenderTransforms(asset, mRenderMatrix);
+    }
+}
+
+LLMatrix4a inverse(const LLMatrix4a& mat);
+
+void Node::updateTransforms(Asset& asset, const LLMatrix4a& parentMatrix)
+{
+    makeMatrixValid();
+    matMul(mMatrix, parentMatrix, mAssetMatrix);
+    mAssetMatrixInv = inverse(mAssetMatrix);
+    
+    S32 my_index = this - &asset.mNodes[0];
+
+    for (auto& childIndex : mChildren)
+    {
+        Node& child = asset.mNodes[childIndex];
+        child.mParent = my_index;
+        child.updateTransforms(asset, mAssetMatrix);
+    }
+}
+
+void Asset::updateTransforms()
+{
+    for (auto& scene : mScenes)
+    {
+        scene.updateTransforms(*this);
+    }
+}
+
+void Asset::updateRenderTransforms(const LLMatrix4a& 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);
+        }
+    }
+
+#endif
+
+}
+
+S32 Asset::lineSegmentIntersect(const LLVector4a& start, const LLVector4a& end,
+    LLVector4a* intersection,         // return the intersection point
+    LLVector2* tex_coord,            // return the texture coordinates of the intersection point
+    LLVector4a* normal,               // return the surface normal at the intersection point
+    LLVector4a* tangent,             // return the surface tangent at the intersection point
+    S32* primitive_hitp
+)
+{
+    S32 node_hit = -1;
+    S32 primitive_hit = -1;
+
+    LLVector4a local_start;
+    LLVector4a asset_end = end;
+    LLVector4a local_end;
+    LLVector4a p;
+
+
+    for (auto& node : mNodes)
+    {
+        if (node.mMesh != INVALID_INDEX)
+        {
+            
+            bool newHit = false;
+
+            // transform start and end to this node's local space
+            node.mAssetMatrixInv.affineTransform(start, local_start);
+            node.mAssetMatrixInv.affineTransform(asset_end, local_end);
+
+            Mesh& mesh = mMeshes[node.mMesh];
+            for (auto& primitive : mesh.mPrimitives)
+            {
+                const LLVolumeTriangle* tri = primitive.lineSegmentIntersect(local_start, local_end, &p, tex_coord, normal, tangent);
+                if (tri)
+                {
+                    newHit = true;
+                    local_end = p;
+
+                    // pointer math to get the node index
+                    node_hit = &node - &mNodes[0];
+                    llassert(&mNodes[node_hit] == &node);
+
+                    //pointer math to get the primitive index
+                    primitive_hit = &primitive - &mesh.mPrimitives[0];
+                    llassert(&mesh.mPrimitives[primitive_hit] == &primitive);
+                }
+            }
+
+            if (newHit)
+            {
+                // shorten line segment on hit
+                node.mAssetMatrix.affineTransform(p, asset_end); 
+
+                // transform results back to asset space
+                if (intersection)
+                {
+                    *intersection = asset_end;
+                }
+
+                if (normal || tangent)
+                {
+                    LLMatrix4 normalMatrix(node.mAssetMatrixInv.getF32ptr());
+
+                    normalMatrix.transpose();
+
+                    LLMatrix4a norm_mat;
+                    norm_mat.loadu((F32*)normalMatrix.mMatrix);
+
+                    if (normal)
+                    {
+                        LLVector4a n = *normal;
+                        F32 w = n.getF32ptr()[3];
+                        n.getF32ptr()[3] = 0.0f;
+
+                        norm_mat.affineTransform(n, *normal);
+                        normal->getF32ptr()[3] = w;
+                    }
+
+                    if (tangent)
+                    {
+                        LLVector4a t = *tangent;
+                        F32 w = t.getF32ptr()[3];
+                        t.getF32ptr()[3] = 0.0f;
+
+                        norm_mat.affineTransform(t, *tangent);
+                        tangent->getF32ptr()[3] = w;
+                    }
+                }
+            }
+        }
+    }
+
+    if (node_hit != -1)
+    {
+        if (primitive_hitp)
+        {
+            *primitive_hitp = primitive_hit;
+        }
+    }
+
+    return node_hit;
+}
+
+
+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);
+        mMatrixValid = true;
+    }
+}
+
+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]);
+
+        mScale.set_value(t.get_column(0).length(), t.get_column(1).length(), t.get_column(2).length());
+        mRotation.set_value(t);
+        mTRSValid = true;
+    }
+}
+
+void Node::setRotation(const glh::quaternionf& q)
+{
+    makeTRSValid();
+    mRotation = q;
+    mMatrixValid = false;
+}
+
+void Node::setTranslation(const glh::vec3f& t)
+{
+    makeTRSValid();
+    mTranslation = t;
+    mMatrixValid = false;
+}
+
+void Node::setScale(const glh::vec3f& s)
+{
+    makeTRSValid();
+    mScale = s;
+    mMatrixValid = false;
+}
+
+const Node& Node::operator=(const tinygltf::Node& src)
+{
+    F32* dstMatrix = mMatrix.getF32ptr();
+
+    if (src.matrix.size() == 16)
+    {
+        // Node has a transformation matrix, just copy it
+        for (U32 i = 0; i < 16; ++i)
+        {
+            dstMatrix[i] = (F32)src.matrix[i];
+        }
+
+        mMatrixValid = true;
+    }
+    else if (!src.rotation.empty() || !src.translation.empty() || !src.scale.empty())
+    {
+        // node has rotation/translation/scale, convert to matrix
+        if (src.rotation.size() == 4)
+        {
+            mRotation = glh::quaternionf((F32)src.rotation[0], (F32)src.rotation[1], (F32)src.rotation[2], (F32)src.rotation[3]);
+        }
+
+        if (src.translation.size() == 3)
+        {
+            mTranslation = glh::vec3f((F32)src.translation[0], (F32)src.translation[1], (F32)src.translation[2]);
+        }
+
+        glh::vec3f scale;
+        if (src.scale.size() == 3)
+        {
+            mScale = glh::vec3f((F32)src.scale[0], (F32)src.scale[1], (F32)src.scale[2]);
+        }
+        else
+        {
+            mScale.set_value(1.f, 1.f, 1.f);
+        }
+
+        mTRSValid = true;
+    }
+    else
+    {
+        // node specifies no transformation, set to identity
+        mMatrix.setIdentity();
+    }
+
+    mChildren = src.children;
+    mMesh = src.mesh;
+    mSkin = src.skin;
+    mName = src.name;
+
+    return *this;
+}
+
+void Asset::render(bool opaque, bool rigged)
+{
+    if (rigged)
+    {
+        gGL.loadIdentity();
+    }
+
+    for (auto& node : mNodes)
+    {
+        if (node.mSkin != INVALID_INDEX)
+        {
+            if (rigged)
+            {
+                Skin& skin = mSkins[node.mSkin];
+                skin.uploadMatrixPalette(*this, node);
+            }
+            else
+            {
+                //skip static nodes if we're rendering rigged
+                continue;
+            }
+        }
+        else if (rigged)
+        {
+            // skip rigged nodes if we're not rendering rigged
+            continue;
+        }
+
+
+        if (node.mMesh != INVALID_INDEX)
+        {
+            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];
+
+                    if ((material.mMaterial->mAlphaMode == LLGLTFMaterial::ALPHA_MODE_BLEND) == opaque)
+                    {
+                        continue;
+                    }
+                    material.mMaterial->bind();
+                    cull = !material.mMaterial->mDoubleSided;
+                }
+                else
+                {
+                    if (!opaque)
+                    {
+                        continue;
+                    }
+                    LLFetchedGLTFMaterial::sDefault.bind();
+                }
+
+                LLGLDisable cull_face(!cull ? GL_CULL_FACE : 0);
+
+                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());
+                }
+
+            }
+        }
+    }
+}
+
+void Asset::renderOpaque()
+{
+    render(true);
+}
+
+void Asset::renderTransparent()
+{
+    render(false);
+}
+
+void Asset::update()
+{
+    F32 dt = gFrameTimeSeconds - mLastUpdateTime;
+
+    if (dt > 0.f)
+    {
+        mLastUpdateTime = gFrameTimeSeconds;
+        if (mAnimations.size() > 0)
+        {
+            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);
+        }
+
+        updateTransforms();
+    }
+}
+
+void Asset::allocateGLResources(const std::string& filename, const tinygltf::Model& model)
+{
+    // do images first as materials may depend on images
+    for (auto& image : mImages)
+    {
+        image.allocateGLResources();
+    }
+
+    // do materials before meshes as meshes may depend on materials
+    for (U32 i = 0; i < mMaterials.size(); ++i)
+    {
+        mMaterials[i].allocateGLResources(*this);
+        LLTinyGLTFHelper::getMaterialFromModel(filename, model, i, mMaterials[i].mMaterial, mMaterials[i].mName, true);
+    }
+
+    for (auto& mesh : mMeshes)
+    {
+        mesh.allocateGLResources(*this);
+    }
+
+    for (auto& animation : mAnimations)
+    {
+        animation.allocateGLResources(*this);
+    }
+
+    for (auto& skin : mSkins)
+    {
+        skin.allocateGLResources(*this);
+    }
+}
+
+const Asset& Asset::operator=(const tinygltf::Model& src)
+{
+    mScenes.resize(src.scenes.size());
+    for (U32 i = 0; i < src.scenes.size(); ++i)
+    {
+        mScenes[i] = src.scenes[i];
+    }
+
+    mNodes.resize(src.nodes.size());
+    for (U32 i = 0; i < src.nodes.size(); ++i)
+    {
+        mNodes[i] = src.nodes[i];
+    }
+
+    mMeshes.resize(src.meshes.size());
+    for (U32 i = 0; i < src.meshes.size(); ++i)
+    {
+        mMeshes[i] = src.meshes[i];
+    }
+
+    mMaterials.resize(src.materials.size());
+    for (U32 i = 0; i < src.materials.size(); ++i)
+    {
+        mMaterials[i] = src.materials[i];
+    }
+
+    mBuffers.resize(src.buffers.size());
+    for (U32 i = 0; i < src.buffers.size(); ++i)
+    {
+        mBuffers[i] = src.buffers[i];
+    }
+
+    mBufferViews.resize(src.bufferViews.size());
+    for (U32 i = 0; i < src.bufferViews.size(); ++i)
+    {
+        mBufferViews[i] = src.bufferViews[i];
+    }
+
+    mTextures.resize(src.textures.size());
+    for (U32 i = 0; i < src.textures.size(); ++i)
+    {
+        mTextures[i] = src.textures[i];
+    }
+
+    mSamplers.resize(src.samplers.size());
+    for (U32 i = 0; i < src.samplers.size(); ++i)
+    {
+        mSamplers[i] = src.samplers[i];
+    }
+
+    mImages.resize(src.images.size());
+    for (U32 i = 0; i < src.images.size(); ++i)
+    {
+        mImages[i] = src.images[i];
+    }
+
+    mAccessors.resize(src.accessors.size());
+    for (U32 i = 0; i < src.accessors.size(); ++i)
+    {
+        mAccessors[i] = src.accessors[i];
+    }
+
+    mAnimations.resize(src.animations.size());
+    for (U32 i = 0; i < src.animations.size(); ++i)
+    {
+        mAnimations[i] = src.animations[i];
+    }
+
+    mSkins.resize(src.skins.size());
+    for (U32 i = 0; i < src.skins.size(); ++i)
+    {
+        mSkins[i] = src.skins[i];
+    }
+ 
+    return *this;
+}
+
+const Material& Material::operator=(const tinygltf::Material& src)
+{
+    mName = src.name;
+    return *this;
+}
+
+void Material::allocateGLResources(Asset& asset)
+{
+    // allocate material
+    mMaterial = new LLFetchedGLTFMaterial();
+}
+
+const Mesh& Mesh::operator=(const tinygltf::Mesh& src)
+{
+    mPrimitives.resize(src.primitives.size());
+    for (U32 i = 0; i < src.primitives.size(); ++i)
+    {
+        mPrimitives[i] = src.primitives[i];
+    }
+
+    mWeights = src.weights;
+    mName = src.name;
+
+    return *this;
+}
+
+void Mesh::allocateGLResources(Asset& asset)
+{
+    for (auto& primitive : mPrimitives)
+    {
+        primitive.allocateGLResources(asset);
+    }
+}
+
+const Scene& Scene::operator=(const tinygltf::Scene& src)
+{
+    mNodes = src.nodes;
+    mName = src.name;
+
+    return *this;
+}
+
+const Texture& Texture::operator=(const tinygltf::Texture& src)
+{
+    mSampler = src.sampler;
+    mSource = src.source;
+    mName = src.name;
+
+    return *this;
+}
+
+const Sampler& Sampler::operator=(const tinygltf::Sampler& src)
+{
+    mMagFilter = src.magFilter;
+    mMinFilter = src.minFilter;
+    mWrapS = src.wrapS;
+    mWrapT = src.wrapT;
+    mName = src.name;
+
+    return *this;
+}
+
+void Skin::uploadMatrixPalette(Asset& asset, Node& node)
+{
+    // prepare matrix palette
+
+    // modelview will be applied by the shader, so assume matrix palette is in asset space
+    std::vector<glh::matrix4f> t_mp;
+
+    t_mp.resize(mJoints.size());
+
+    for (U32 i = 0; i < mJoints.size(); ++i)
+    {
+        Node& joint = asset.mNodes[mJoints[i]];
+        
+        //t_mp[i].set_value(joint.mRenderMatrix.getF32ptr());
+        //t_mp[i] = t_mp[i] * mInverseBindMatricesData[i];
+
+        //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];
+
+    }
+
+    std::vector<F32> glmp;
+
+    glmp.resize(mJoints.size() * 12);
+
+    F32* mp = glmp.data();
+
+    for (U32 i = 0; i < mJoints.size(); ++i)
+    {
+        F32* m = (F32*)t_mp[i].m;
+
+        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];
+    }
+
+    LLGLSLShader::sCurBoundShaderPtr->uniformMatrix3x4fv(LLViewerShaderMgr::AVATAR_MATRIX,
+        mJoints.size(),
+        FALSE,
+        (GLfloat*)glmp.data());
+}
+
diff --git a/indra/newview/gltf/asset.h b/indra/newview/gltf/asset.h
new file mode 100644
index 0000000000..5ceac74a8a
--- /dev/null
+++ b/indra/newview/gltf/asset.h
@@ -0,0 +1,264 @@
+#pragma once
+
+/**
+ * @file asset.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
+ * $/LicenseInfo$
+ */
+
+#include "llvertexbuffer.h"
+#include "llvolumeoctree.h"
+#include "../lltinygltfhelper.h"
+#include "accessor.h"
+#include "primitive.h"
+#include "animation.h"
+
+extern F32SecondsImplicit       gFrameTimeSeconds;
+
+// LL GLTF Implementation
+namespace LL
+{
+    namespace GLTF
+    {
+        class Asset;
+
+        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;
+            std::string mName;
+
+            const Material& operator=(const tinygltf::Material& src);
+
+            void allocateGLResources(Asset& asset);
+        };
+
+        class Mesh
+        {
+        public:
+            std::vector<Primitive> mPrimitives;
+            std::vector<double> mWeights;
+            std::string mName;
+
+            const Mesh& operator=(const tinygltf::Mesh& src);
+
+            void allocateGLResources(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
+
+            glh::vec3f mTranslation;
+            glh::quaternionf mRotation;
+            glh::vec3f mScale;
+
+            // if true, mMatrix is valid and up to date
+            bool mMatrixValid = false;
+
+            // if true, translation/rotation/scale are valid and up to date
+            bool mTRSValid = false;
+
+            bool mNeedsApplyMatrix = false;
+
+            std::vector<S32> mChildren;
+            S32 mParent = INVALID_INDEX;
+
+            S32 mMesh = INVALID_INDEX;
+            S32 mSkin = INVALID_INDEX;
+
+            std::string mName;
+
+            const Node& operator=(const tinygltf::Node& src);
+
+            // 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);
+
+            // update mAssetMatrix and mAssetMatrixInv
+            void updateTransforms(Asset& asset, const LLMatrix4a& parentMatrix);
+
+            // ensure mMatrix is valid -- if mMatrixValid is false and mTRSValid is true, will update mMatrix to match Translation/Rotation/Scale
+            void makeMatrixValid();
+
+            // ensure Translation/Rotation/Scale are valid -- if mTRSValid is false and mMatrixValid is true, will update Translation/Rotation/Scale to match mMatrix
+            void makeTRSValid();
+
+            // Set rotation of this node
+            // SIDE EFFECT: invalidates mMatrix
+            void setRotation(const glh::quaternionf& rotation);
+
+            // Set translation of this node
+            // SIDE EFFECT: invalidates mMatrix
+            void setTranslation(const glh::vec3f& translation);
+
+            // Set scale of this node
+            // SIDE EFFECT: invalidates mMatrix
+            void setScale(const glh::vec3f& scale);
+        };
+
+        class Skin
+        {
+        public:
+            S32 mInverseBindMatrices = INVALID_INDEX;
+            S32 mSkeleton = INVALID_INDEX;
+            std::vector<S32> mJoints;
+            std::string mName;
+            std::vector<glh::matrix4f> mInverseBindMatricesData;
+
+            void allocateGLResources(Asset& asset);
+            void uploadMatrixPalette(Asset& asset, Node& node);
+
+            const Skin& operator=(const tinygltf::Skin& src);
+        };
+
+        class Scene
+        {
+        public:
+            std::vector<S32> mNodes;
+            std::string mName;
+
+            const Scene& operator=(const tinygltf::Scene& src);
+
+            void updateTransforms(Asset& asset);
+            void updateRenderTransforms(Asset& asset, const LLMatrix4a& modelview);
+        };
+
+        class Texture
+        {
+        public:
+            S32 mSampler = INVALID_INDEX;
+            S32 mSource = INVALID_INDEX;
+            std::string mName;
+
+            const Texture& operator=(const tinygltf::Texture& src);
+        };
+
+        class Sampler
+        {
+        public:
+            S32 mMagFilter;
+            S32 mMinFilter;
+            S32 mWrapS;
+            S32 mWrapT;
+            std::string mName;
+
+            const Sampler& operator=(const tinygltf::Sampler& src);
+        };
+
+        class Image
+        {
+        public:
+            std::string mName;
+            std::string mUri;
+            std::string mMimeType;
+            std::vector<U8> mData;
+            S32 mWidth;
+            S32 mHeight;
+            S32 mComponent;
+            S32 mBits;
+            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
+
+            }
+        };
+
+        // C++ representation of a GLTF Asset
+        class Asset : public LLRefCount
+        {
+        public:
+            std::vector<Scene> mScenes;
+            std::vector<Node> mNodes;
+            std::vector<Mesh> mMeshes;
+            std::vector<Material> mMaterials;
+            std::vector<Buffer> mBuffers;
+            std::vector<BufferView> mBufferViews;
+            std::vector<Texture> mTextures;
+            std::vector<Sampler> mSamplers;
+            std::vector<Image> mImages;
+            std::vector<Accessor> mAccessors;
+            std::vector<Animation> mAnimations;
+            std::vector<Skin> mSkins;
+
+            // 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);
+
+            // Called periodically (typically once per frame)
+            // Any ongoing work (such as animations) should be handled here
+            // NOT guaranteed to be called every frame
+            // MAY be called more than once per frame
+            // Upon return, all Node Matrix transforms should be up to date
+            void update();
+
+            // update asset-to-node and node-to-asset transforms
+            void updateTransforms();
+
+            // update node render transforms
+            void updateRenderTransforms(const LLMatrix4a& modelview);
+
+            void render(bool opaque, bool rigged = false);
+            void renderOpaque();
+            void renderTransparent();
+
+            // 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
+            S32 lineSegmentIntersect(const LLVector4a& start, const LLVector4a& end,
+                LLVector4a* intersection = nullptr,         // return the intersection point
+                LLVector2* tex_coord = nullptr,            // return the texture coordinates of the intersection point
+                LLVector4a* normal = nullptr,               // return the surface normal at the intersection point
+                LLVector4a* tangent = nullptr,             // return the surface tangent at the intersection point
+                S32* primitive_hitp = nullptr           // return the index of the primitive that was hit
+            );
+
+            const Asset& operator=(const tinygltf::Model& src);
+
+        };
+    }
+}
diff --git a/indra/newview/gltf/buffer_util.h b/indra/newview/gltf/buffer_util.h
new file mode 100644
index 0000000000..4e6f5901e7
--- /dev/null
+++ b/indra/newview/gltf/buffer_util.h
@@ -0,0 +1,402 @@
+#pragma once
+
+/**
+ * @file buffer_util.inl
+ * @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
+ * $/LicenseInfo$
+ */
+
+// inline template implementations for copying data out of GLTF buffers
+// DO NOT include from header files to avoid the need to rebuild the whole project
+// whenever we add support for more types
+
+#ifdef _MSC_VER
+#define LL_FUNCSIG __FUNCSIG__ 
+#else
+#define LL_FUNCSIG __PRETTY_FUNCTION__
+#endif
+
+namespace LL
+{
+    namespace GLTF
+    {
+        // copy one Scalar from src to dst
+        template<class S, class T>
+        static 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)
+        {
+            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)
+        {
+            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)
+        {
+            LL_ERRS() << "TODO: implement " << LL_FUNCSIG << LL_ENDL;
+        }
+
+        // copy one vec2 from src to dst
+        template<class S, class T>
+        static void copyMat2(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 copyMat3(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 copyMat4(S* src, T& dst)
+        {
+            LL_ERRS() << "TODO: implement " << LL_FUNCSIG << LL_ENDL;
+        }
+
+        //=========================================================================================================
+        // 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)
+        {
+            dst = *src;
+        }
+
+        template<>
+        void copyScalar<U32, U32>(U32* src, U32& dst)
+        {
+            dst = *src;
+        }
+
+        template<>
+        void copyScalar<U32, U16>(U32* src, U16& dst)
+        {
+            dst = *src;
+        }
+
+        template<>
+        void copyScalar<U16, U16>(U16* src, U16& dst)
+        {
+            dst = *src;
+        }
+
+        template<>
+        void copyScalar<U16, U32>(U16* src, U32& dst)
+        {
+            dst = *src;
+        }
+
+        template<>
+        void copyScalar<U8, U16>(U8* src, U16& dst)
+        {
+            dst = *src;
+        }
+
+        template<>
+        void copyScalar<U8, U32>(U8* src, U32& dst)
+        {
+            dst = *src;
+        }
+
+        template<>
+        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)
+        {
+            dst.set_value(src[0], src[1], src[2]);
+        }
+
+        template<>
+        void copyVec3<F32, LLVector4a>(F32* src, LLVector4a& dst)
+        {
+            dst.load3(src);
+        }
+
+        template<>
+        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)
+        {
+            dst.set(src[0], src[1], src[2], src[3]);
+        }
+
+        template<>
+        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)
+        {
+            dst.set(src[0]*255, src[1]*255, src[2]*255, src[3]*255);
+        }
+
+        template<>
+        void copyVec4<F32, LLVector4a>(F32* src, LLVector4a& dst)
+        {
+            dst.loadua(src);
+        }
+
+        template<>
+        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)
+        {
+            dst.set(src[0], src[1], src[2], src[3]);
+        }
+
+        template<>
+        void copyVec4<F32, glh::quaternionf>(F32* src, glh::quaternionf& dst)
+        {
+            dst.set_value(src);
+        }
+
+        template<>
+        void copyMat4<F32, glh::matrix4f>(F32* src, glh::matrix4f& dst)
+        {
+            dst.set_value(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)
+        {
+            for (S32 i = 0; i < count; ++i)
+            {
+                copyScalar(src, *dst);
+                dst++;
+                src = (S*)((U8*)src + stride);
+            }
+        }
+
+        // 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)
+        {
+            for (S32 i = 0; i < count; ++i)
+            {
+                copyVec2(src, *dst);
+                dst++;
+                src = (S*)((U8*)src + stride);
+            }
+        }
+
+        // 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)
+        {
+            for (S32 i = 0; i < count; ++i)
+            {
+                copyVec3(src, *dst);
+                dst++;
+                src = (S*)((U8*)src + stride);
+            }
+        }
+
+        // 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)
+        {
+            for (S32 i = 0; i < count; ++i)
+            {
+                copyVec4(src, *dst);
+                dst++;
+                src = (S*)((U8*)src + stride);
+            }
+        }
+
+        // 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)
+        {
+            for (S32 i = 0; i < count; ++i)
+            {
+                copyMat2(src, *dst);
+                dst++;
+                src = (S*)((U8*)src + stride);
+            }
+        }
+
+        // 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)
+        {
+            for (S32 i = 0; i < count; ++i)
+            {
+                copyMat3(src, *dst);
+                dst++;
+                src = (S*)((U8*)src + stride);
+            }
+        }
+
+        // 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)
+        {
+            for (S32 i = 0; i < count; ++i)
+            {
+                copyMat4(src, *dst);
+                dst++;
+                src = (S*)((U8*)src + stride);
+            }
+        }
+
+        template<class S, class T>
+        static void copy(Asset& asset, Accessor& accessor, const S* src, LLStrider<T>& dst, S32 byteStride)
+        {
+            if (accessor.mType == (S32)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)
+            {
+                S32 stride = byteStride == 0 ? sizeof(S) * 2 : byteStride;
+                copyVec2((S*)src, dst, stride, accessor.mCount);
+            }
+            else if (accessor.mType == (S32)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)
+            {
+                S32 stride = byteStride == 0 ? sizeof(S) * 4 : byteStride;
+                copyVec4((S*)src, dst, stride, accessor.mCount);
+            }
+            else if (accessor.mType == (S32)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)
+            {
+                S32 stride = byteStride == 0 ? sizeof(S) * 9 : byteStride;
+                copyMat3((S*)src, dst, stride, accessor.mCount);
+            }
+            else if (accessor.mType == (S32)Accessor::Type::MAT4)
+            {
+                S32 stride = byteStride == 0 ? sizeof(S) * 16 : byteStride;
+                copyMat4((S*)src, dst, stride, accessor.mCount);
+            }
+            else
+            {
+                LL_ERRS("GLTF") << "Unsupported accessor type" << LL_ENDL;
+            }
+        }
+
+        // copy data from accessor to strider
+        template<class T>
+        static 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)
+            {
+                LL::GLTF::copy(asset, accessor, (const F32*)src, dst, bufferView.mByteStride);
+            }
+            else if (accessor.mComponentType == TINYGLTF_COMPONENT_TYPE_UNSIGNED_SHORT)
+            {
+                LL::GLTF::copy(asset, accessor, (const U16*)src, dst, bufferView.mByteStride);
+            }
+            else if (accessor.mComponentType == TINYGLTF_COMPONENT_TYPE_UNSIGNED_INT)
+            {
+                LL::GLTF::copy(asset, accessor, (const U32*)src, dst, bufferView.mByteStride);
+            }
+            else if (accessor.mComponentType == TINYGLTF_COMPONENT_TYPE_UNSIGNED_BYTE)
+            {
+                LL::GLTF::copy(asset, accessor, (const U8*)src, dst, bufferView.mByteStride);
+            }
+            else if (accessor.mComponentType == TINYGLTF_COMPONENT_TYPE_SHORT)
+            {
+                LL::GLTF::copy(asset, accessor, (const S16*)src, dst, bufferView.mByteStride);
+            }
+            else if (accessor.mComponentType == TINYGLTF_COMPONENT_TYPE_BYTE)
+            {
+                LL::GLTF::copy(asset, accessor, (const S8*)src, dst, bufferView.mByteStride);
+            }
+            else if (accessor.mComponentType == TINYGLTF_COMPONENT_TYPE_DOUBLE)
+            {
+                LL::GLTF::copy(asset, accessor, (const F64*)src, dst, bufferView.mByteStride);
+            }
+            else
+            {
+                LL_ERRS("GLTF") << "Unsupported component type" << LL_ENDL;
+            }
+        }
+
+        // copy data from accessor to vector
+        template<class T>
+        static void copy(Asset& asset, Accessor& accessor, std::vector<T>& dst)
+        {
+            dst.resize(accessor.mCount);
+            LLStrider<T> strider = dst.data();
+            copy(asset, accessor, strider);
+        }
+    }
+}
+
diff --git a/indra/newview/gltf/primitive.cpp b/indra/newview/gltf/primitive.cpp
new file mode 100644
index 0000000000..b57a0af18d
--- /dev/null
+++ b/indra/newview/gltf/primitive.cpp
@@ -0,0 +1,400 @@
+/**
+ * @file primitive.cpp
+ * @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
+ * $/LicenseInfo$
+ */
+
+#include "../llviewerprecompiledheaders.h"
+
+#include "asset.h"
+#include "buffer_util.h"
+
+#include "../lltinygltfhelper.h"
+
+using namespace LL::GLTF;
+
+void Primitive::allocateGLResources(Asset& asset)
+{
+    // allocate vertex buffer
+    // We diverge from the intent of the GLTF format here to work with our existing render pipeline
+    // GLTF wants us to copy the buffer views into GPU storage as is and build render commands that source that data.
+    // For our engine, though, it's better to rearrange the buffers at load time into a layout that's more consistent.
+    // The GLTF native approach undoubtedly works well if you can count on VAOs, but VAOs perform much worse with our scenes.
+
+    // load vertex data
+    for (auto& it : mAttributes)
+    {
+        const std::string& attribName = it.first;
+        Accessor& accessor = asset.mAccessors[it.second];
+
+        // load vertex data
+        if (attribName == "POSITION")
+        {
+            copy(asset, accessor, mPositions);
+        }
+        else if (attribName == "NORMAL")
+        {
+            copy(asset, accessor, mNormals);
+        }
+        else if (attribName == "TANGENT")
+        {
+            copy(asset, accessor, mTangents);
+        }
+        else if (attribName == "COLOR_0")
+        {
+            copy(asset, accessor, mColors);
+        }
+        else if (attribName == "TEXCOORD_0")
+        {
+            copy(asset, accessor, mTexCoords);
+        }
+        else if (attribName == "JOINTS_0")
+        {
+            copy(asset, accessor, mJoints);
+        }
+        else if (attribName == "WEIGHTS_0")
+        {
+            copy(asset, accessor, mWeights);
+        }
+    }
+
+    // copy index buffer
+    if (mIndices != INVALID_INDEX)
+    {
+        Accessor& accessor = asset.mAccessors[mIndices];
+        copy(asset, accessor, mIndexArray);
+    }
+
+    U32 mask = ATTRIBUTE_MASK;
+    
+    if (!mWeights.empty())
+    {
+        mask |= LLVertexBuffer::MAP_WEIGHT4;
+    }
+
+    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());
+
+    if (!mIndexArray.empty())
+    {
+        mVertexBuffer->setIndexData(mIndexArray.data());
+    }
+
+    if (mTexCoords.empty())
+    {
+        mTexCoords.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());
+
+    for (auto& tc : mTexCoords)
+    {
+        tc[1] = 1.f - tc[1];
+    }
+
+    if (mColors.empty())
+    {
+        mColors.resize(mPositions.size(), LLColor4U::white);
+    }
+    
+    // bake material basecolor into color array
+    if (mMaterial != INVALID_INDEX)
+    {
+        const Material& material = asset.mMaterials[mMaterial];
+        LLColor4 baseColor = material.mMaterial->mBaseColor;
+        for (auto& dst : mColors)
+        {
+            dst = LLColor4U(baseColor * LLColor4(dst));
+        }
+    }
+
+    mVertexBuffer->setColorData(mColors.data());
+
+    if (mNormals.empty())
+    {
+        mNormals.resize(mPositions.size(), LLVector4a(0, 0, 1, 0));
+    }
+    
+    mVertexBuffer->setNormalData(mNormals.data());
+
+    if (mTangents.empty())
+    {
+        // TODO: generate tangents if needed
+        mTangents.resize(mPositions.size(), LLVector4a(1, 0, 0, 1));
+    }
+
+    mVertexBuffer->setTangentData(mTangents.data());
+
+    if (!mWeights.empty())
+    {
+        std::vector<LLVector4a> weight_data;
+        weight_data.resize(mWeights.size());
+
+        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());
+    }
+    
+    createOctree();
+    
+    mVertexBuffer->unbind();
+}
+
+void initOctreeTriangle(LLVolumeTriangle* tri, F32 scaler, S32 i0, S32 i1, S32 i2, const LLVector4a& v0, const LLVector4a& v1, const LLVector4a& v2)
+{
+    //store pointers to vertex data
+    tri->mV[0] = &v0;
+    tri->mV[1] = &v1;
+    tri->mV[2] = &v2;
+
+    //store indices
+    tri->mIndex[0] = i0;
+    tri->mIndex[1] = i1;
+    tri->mIndex[2] = i2;
+
+    //get minimum point
+    LLVector4a min = v0;
+    min.setMin(min, v1);
+    min.setMin(min, v2);
+
+    //get maximum point
+    LLVector4a max = v0;
+    max.setMax(max, v1);
+    max.setMax(max, v2);
+
+    //compute center
+    LLVector4a center;
+    center.setAdd(min, max);
+    center.mul(0.5f);
+
+    tri->mPositionGroup = center;
+
+    //compute "radius"
+    LLVector4a size;
+    size.setSub(max, min);
+
+    tri->mRadius = size.getLength3().getF32() * scaler;
+}
+
+void Primitive::createOctree()
+{
+    // create octree
+    mOctree = new LLVolumeOctree();
+
+    F32 scaler = 0.25f;
+
+    if (mMode == TINYGLTF_MODE_TRIANGLES)
+    {
+        const U32 num_triangles = mVertexBuffer->getNumIndices() / 3;
+        // Initialize all the triangles we need
+        mOctreeTriangles.resize(num_triangles);
+
+        for (U32 triangle_index = 0; triangle_index < num_triangles; ++triangle_index)
+        { //for each triangle
+            const U32 index = triangle_index * 3;
+            LLVolumeTriangle* tri = &mOctreeTriangles[triangle_index];
+            S32 i0 = mIndexArray[index];
+            S32 i1 = mIndexArray[index + 1];
+            S32 i2 = mIndexArray[index + 2];
+
+            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)
+    {
+        const U32 num_triangles = mVertexBuffer->getNumIndices() - 2;
+        // Initialize all the triangles we need
+        mOctreeTriangles.resize(num_triangles);
+
+        for (U32 triangle_index = 0; triangle_index < num_triangles; ++triangle_index)
+        { //for each triangle
+            const U32 index = triangle_index + 2;
+            LLVolumeTriangle* tri = &mOctreeTriangles[triangle_index];
+            S32 i0 = mIndexArray[index];
+            S32 i1 = mIndexArray[index - 1];
+            S32 i2 = mIndexArray[index - 2];
+
+            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_FAN)
+    {
+        const U32 num_triangles = mVertexBuffer->getNumIndices() - 2;
+        // Initialize all the triangles we need
+        mOctreeTriangles.resize(num_triangles);
+
+        for (U32 triangle_index = 0; triangle_index < num_triangles; ++triangle_index)
+        { //for each triangle
+            const U32 index = triangle_index + 2;
+            LLVolumeTriangle* tri = &mOctreeTriangles[triangle_index];
+            S32 i0 = mIndexArray[0];
+            S32 i1 = mIndexArray[index - 1];
+            S32 i2 = mIndexArray[index - 2];
+
+            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_POINTS ||
+            mMode == TINYGLTF_MODE_LINE ||
+        mMode == TINYGLTF_MODE_LINE_LOOP ||
+        mMode == TINYGLTF_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;
+    }
+
+    //remove unneeded octree layers
+    while (!mOctree->balance()) {}
+
+    //calculate AABB for each node
+    LLVolumeOctreeRebound rebound;
+    rebound.traverse(mOctree);
+}
+
+const LLVolumeTriangle* Primitive::lineSegmentIntersect(const LLVector4a& start, const LLVector4a& end,
+    LLVector4a* intersection, LLVector2* tex_coord, LLVector4a* normal, LLVector4a* tangent_out)
+{
+    if (mOctree.isNull())
+    {
+        return nullptr;
+    }
+
+    LLVector4a dir;
+    dir.setSub(end, start);
+
+    F32 closest_t = 2.f; // must be larger than 1
+
+    //create a proxy LLVolumeFace for the raycast
+    LLVolumeFace face;
+    face.mPositions = mPositions.data();
+    face.mTexCoords = mTexCoords.data();
+    face.mNormals = mNormals.data();
+    face.mTangents = mTangents.data();
+    face.mIndices = nullptr; // unreferenced
+
+    face.mNumIndices = mIndexArray.size();
+    face.mNumVertices = mPositions.size();
+
+    LLOctreeTriangleRayIntersect intersect(start, dir, &face, &closest_t, intersection, tex_coord, normal, tangent_out);
+    intersect.traverse(mOctree);
+
+    // null out proxy data so it doesn't get freed
+    face.mPositions = face.mNormals = face.mTangents = nullptr;
+    face.mIndices = nullptr;
+    face.mTexCoords = nullptr;
+
+    return intersect.mHitTriangle;
+}
+
+Primitive::~Primitive()
+{
+    mOctree = nullptr;
+}
+
+
+const Primitive& Primitive::operator=(const tinygltf::Primitive& src)
+{
+    // 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;
+    default:
+        mGLMode = GL_TRIANGLES;
+    }
+
+    return *this;
+}
diff --git a/indra/newview/gltf/primitive.h b/indra/newview/gltf/primitive.h
new file mode 100644
index 0000000000..07e8e7deb2
--- /dev/null
+++ b/indra/newview/gltf/primitive.h
@@ -0,0 +1,93 @@
+#pragma once
+
+/**
+ * @file primitive.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
+ * $/LicenseInfo$
+ */
+
+#include "llvertexbuffer.h"
+#include "llvolumeoctree.h"
+
+// LL GLTF Implementation
+namespace LL
+{
+    namespace GLTF
+    {
+        class Asset;
+
+        constexpr U32 ATTRIBUTE_MASK =
+            LLVertexBuffer::MAP_VERTEX |
+            LLVertexBuffer::MAP_NORMAL |
+            LLVertexBuffer::MAP_TEXCOORD0 |
+            LLVertexBuffer::MAP_TANGENT |
+            LLVertexBuffer::MAP_COLOR;
+
+        class Primitive
+        {
+        public:
+            ~Primitive();
+
+            // GPU copy of mesh data
+            LLPointer<LLVertexBuffer> mVertexBuffer;
+
+            // CPU copy of mesh data
+            std::vector<LLVector2> mTexCoords;
+            std::vector<LLVector4a> mNormals;
+            std::vector<LLVector4a> mTangents;
+            std::vector<LLVector4a> mPositions;
+            std::vector<LLVector4a> mJoints;
+            std::vector<LLVector4a> mWeights;
+            std::vector<LLColor4U> mColors;
+            std::vector<U32> mIndexArray;
+
+            // 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;
+            S32 mIndices = -1;
+            std::unordered_map<std::string, int> 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 
+            //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,
+                LLVector4a* intersection = NULL,         // return the intersection point
+                LLVector2* tex_coord = NULL,            // return the texture coordinates of the intersection point
+                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);
+        };
+    }
+}