GLTF WIP. Still working on getting transforms working proper and need to figure out our indices.

7 files changed, 660 insertions, 9 deletions

diff --git a/indra/newview/CMakeLists.txt b/indra/newview/CMakeLists.txt
index ed29911a43..7dfe01898a 100644
--- a/indra/newview/CMakeLists.txt
+++ b/indra/newview/CMakeLists.txt
@@ -76,6 +76,7 @@ set(viewer_SOURCE_FILES
     gltf/accessor.cpp
     gltf/primitive.cpp
     gltf/animation.cpp
+    gltf/llgltfloader.cpp
     groupchatlistener.cpp
     llaccountingcostmanager.cpp
     llaisapi.cpp
@@ -744,6 +745,7 @@ set(viewer_HEADER_FILES
     gltf/buffer_util.h
     gltf/primitive.h
     gltf/animation.h
+    gltf/llgltfloader.h
     llaccountingcost.h
     llaccountingcostmanager.h
     llaisapi.h
diff --git a/indra/newview/gltf/asset.cpp b/indra/newview/gltf/asset.cpp
index c210b9c61d..beccb02bd4 100644
--- a/indra/newview/gltf/asset.cpp
+++ b/indra/newview/gltf/asset.cpp
@@ -472,11 +472,14 @@ void Asset::update()
 
             for (auto& image : mImages)
             {
-                if (image.mTexture.notNull())
-                { // HACK - force texture to be loaded full rez
-                    // TODO: calculate actual vsize
-                    image.mTexture->addTextureStats(2048.f * 2048.f);
-                    image.mTexture->setBoostLevel(LLViewerTexture::BOOST_HIGH);
+                if (image.mLoadIntoTexturePipe)
+                {
+                    if (image.mTexture.notNull())
+                    { // HACK - force texture to be loaded full rez
+                        // TODO: calculate actual vsize
+                        image.mTexture->addTextureStats(2048.f * 2048.f);
+                        image.mTexture->setBoostLevel(LLViewerTexture::BOOST_HIGH);
+                    }
                 }
             }
         }
@@ -603,6 +606,7 @@ bool Asset::prep()
                 if (vertex_count[variant] > 0)
                 {
                     U32 mat_idx = mat_id + 1;
+                    #if 0
                     LLVertexBuffer* vb = new LLVertexBuffer(attribute_mask);
 
                     rd.mBatches[variant][mat_idx].mVertexBuffer = vb;
@@ -624,6 +628,7 @@ bool Asset::prep()
                     vb->unmapBuffer();
 
                     vb->unbind();
+                    #endif
                 }
             }
         }
@@ -634,10 +639,10 @@ bool Asset::prep()
     {
         for (auto& primitive : mesh.mPrimitives)
         {
-            llassert(primitive.mVertexBuffer.notNull());
+            //llassert(primitive.mVertexBuffer.notNull());
         }
     }
-
+    #if 0
     // build render batches
     for (S32 node_id = 0; node_id < mNodes.size(); ++node_id)
     {
@@ -664,6 +669,7 @@ bool Asset::prep()
             }
         }
     }
+    #endif
     return true;
 }
 
diff --git a/indra/newview/gltf/asset.h b/indra/newview/gltf/asset.h
index 27821659db..e70fffa986 100644
--- a/indra/newview/gltf/asset.h
+++ b/indra/newview/gltf/asset.h
@@ -286,6 +286,7 @@ namespace LL
             void serialize(boost::json::object& dst) const;
         };
 
+        // Image is for images that we want to load for the given asset.  This acts as an interface into the viewer's texture pipe.
         class Image
         {
         public:
@@ -301,6 +302,8 @@ namespace LL
             S32 mBits = -1;
             S32 mPixelType = -1;
 
+            bool mLoadIntoTexturePipe = false;
+
             LLPointer<LLViewerFetchedTexture> mTexture;
 
             const Image& operator=(const Value& src);
diff --git a/indra/newview/gltf/llgltfloader.cpp b/indra/newview/gltf/llgltfloader.cpp
new file mode 100644
index 0000000000..106c20d4d3
--- /dev/null
+++ b/indra/newview/gltf/llgltfloader.cpp
@@ -0,0 +1,431 @@
+/**
+ * @file LLGLTFLoader.cpp
+ * @brief LLGLTFLoader class implementation
+ *
+ * $LicenseInfo:firstyear=2022&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2022, 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 "llgltfloader.h"
+
+// Import & define single-header gltf import/export lib
+#define TINYGLTF_IMPLEMENTATION
+#define TINYGLTF_USE_CPP14  // default is C++ 11
+
+// tinygltf by default loads image files using STB
+#define STB_IMAGE_IMPLEMENTATION
+// to use our own image loading:
+// 1. replace this definition with TINYGLTF_NO_STB_IMAGE
+// 2. provide image loader callback with TinyGLTF::SetImageLoader(LoadimageDataFunction LoadImageData, void *user_data)
+
+// tinygltf saves image files using STB
+#define STB_IMAGE_WRITE_IMPLEMENTATION
+// similarly, can override with TINYGLTF_NO_STB_IMAGE_WRITE and TinyGLTF::SetImageWriter(fxn, data)
+
+// Additionally, disable inclusion of STB header files entirely with
+// TINYGLTF_NO_INCLUDE_STB_IMAGE
+// TINYGLTF_NO_INCLUDE_STB_IMAGE_WRITE
+#include "tinygltf/tiny_gltf.h"
+
+
+// TODO: includes inherited from dae loader.  Validate / prune
+
+#include "llsdserialize.h"
+#include "lljoint.h"
+
+#include "llmatrix4a.h"
+
+#include <boost/regex.hpp>
+#include <boost/algorithm/string/replace.hpp>
+
+static const std::string lod_suffix[LLModel::NUM_LODS] =
+{
+    "_LOD0",
+    "_LOD1",
+    "_LOD2",
+    "",
+    "_PHYS",
+};
+
+
+LLGLTFLoader::LLGLTFLoader(std::string filename,
+    S32                                 lod,
+    LLModelLoader::load_callback_t      load_cb,
+    LLModelLoader::joint_lookup_func_t  joint_lookup_func,
+    LLModelLoader::texture_load_func_t  texture_load_func,
+    LLModelLoader::state_callback_t     state_cb,
+    void *                              opaque_userdata,
+    JointTransformMap &                 jointTransformMap,
+    JointNameSet &                      jointsFromNodes,
+    std::map<std::string, std::string> &jointAliasMap,
+    U32                                 maxJointsPerMesh,
+    U32                                 modelLimit) //,
+    //bool                                preprocess)
+    : LLModelLoader( filename,
+                     lod,
+                     load_cb,
+                     joint_lookup_func,
+                     texture_load_func,
+                     state_cb,
+                     opaque_userdata,
+                     jointTransformMap,
+                     jointsFromNodes,
+                     jointAliasMap,
+                     maxJointsPerMesh ),
+    //mPreprocessGLTF(preprocess),
+    mMeshesLoaded(false),
+    mMaterialsLoaded(false)
+{
+}
+
+LLGLTFLoader::~LLGLTFLoader() {}
+
+bool LLGLTFLoader::OpenFile(const std::string &filename)
+{
+    tinygltf::TinyGLTF loader;
+    std::string        error_msg;
+    std::string        warn_msg;
+    std::string filename_lc(filename);
+    LLStringUtil::toLower(filename_lc);
+
+    mGltfLoaded = mGLTFAsset.load(filename);
+
+    if (!mGltfLoaded)
+    {
+        if (!warn_msg.empty())
+            LL_WARNS("GLTF_IMPORT") << "gltf load warning: " << warn_msg.c_str() << LL_ENDL;
+        if (!error_msg.empty())
+            LL_WARNS("GLTF_IMPORT") << "gltf load error: " << error_msg.c_str() << LL_ENDL;
+        return false;
+    }
+
+    mMeshesLoaded = parseMeshes();
+    if (mMeshesLoaded) uploadMeshes();
+
+    /*
+    mMaterialsLoaded = parseMaterials();
+    if (mMaterialsLoaded) uploadMaterials();
+    */
+
+    setLoadState(DONE);
+
+    return (mMeshesLoaded);
+}
+
+bool LLGLTFLoader::parseMeshes()
+{
+    if (!mGltfLoaded) return false;
+
+    // 2022-04 DJH Volume params from dae example. TODO understand PCODE
+    LLVolumeParams volume_params;
+    volume_params.setType(LL_PCODE_PROFILE_SQUARE, LL_PCODE_PATH_LINE);
+
+    for (auto node : mGLTFAsset.mNodes)
+    {
+        LLMatrix4    transform;
+        material_map mats;
+        auto meshidx = node.mMesh;
+
+        if (meshidx >= 0)
+        {
+            LLModel* pModel = new LLModel(volume_params, 0.f);
+            auto mesh = mGLTFAsset.mMeshes[meshidx];
+
+            if (populateModelFromMesh(pModel, mesh, mats) && (LLModel::NO_ERRORS == pModel->getStatus()) && validate_model(pModel))
+            {
+                mModelList.push_back(pModel);
+                LLVector3 mesh_scale_vector;
+                LLVector3 mesh_translation_vector;
+                pModel->getNormalizedScaleTranslation(mesh_scale_vector, mesh_translation_vector);
+
+                LLMatrix4 mesh_translation;
+                mesh_translation.setTranslation(mesh_translation_vector);
+                mesh_translation *= transform;
+                transform = mesh_translation;
+
+                LLMatrix4 mesh_scale;
+                mesh_scale.initScale(mesh_scale_vector);
+                mesh_scale *= transform;
+                transform = mesh_scale;
+
+
+                mScene[transform].push_back(LLModelInstance(pModel, node.mName, transform, mats));
+            }
+            else
+            {
+                setLoadState(ERROR_MODEL + pModel->getStatus());
+                delete (pModel);
+                return false;
+            }
+        }
+    }
+
+    return true;
+}
+ 
+bool LLGLTFLoader::populateModelFromMesh(LLModel* pModel, const LL::GLTF::Mesh &mesh, material_map &mats)
+{
+    pModel->mLabel = mesh.mName;
+    pModel->ClearFacesAndMaterials();
+
+    auto prims = mesh.mPrimitives;
+    for (auto prim : prims)
+    {
+        // So primitives already have all of the data we need for a given face in SL land.
+        // Primitives may only ever have a single material assigned to them - as the relation is 1:1 in terms of intended draw call count.
+        // Just go ahead and populate faces direct from the GLTF primitives here.
+        // -Geenz 2025-04-07
+        LLVolumeFace                          face;
+        LLVolumeFace::VertexMapData::PointMap point_map;
+
+        std::vector<LLVolumeFace::VertexData> vertices;
+        std::vector<U16>                      indices;
+
+        LLImportMaterial impMat;
+
+        auto material = mGLTFAsset.mMaterials[prim.mMaterial];
+
+        impMat.mDiffuseColor = LLColor4::white;
+
+
+        for (U32 i = 0; i < prim.getVertexCount(); i++)
+        {
+            LLVolumeFace::VertexData vert;
+            vert.setPosition(prim.mPositions[i]);
+            vert.setNormal(prim.mNormals[i]);
+            vert.mTexCoord = prim.mTexCoords0[i];
+            vertices.push_back(vert);
+        }
+
+        for (S32 i = 0; i < prim.mIndexArray.size(); i++)
+        {
+            indices.push_back(prim.mIndexArray[i]);
+        }
+
+        face.fillFromLegacyData(vertices, indices);
+
+        pModel->getVolumeFaces().push_back(face);
+        pModel->getMaterialList().push_back("mat" + std::to_string(prim.mMaterial));
+        mats["mat" + std::to_string(prim.mMaterial)] = impMat;
+    }
+
+    return true;
+}
+
+bool LLGLTFLoader::parseMaterials()
+{
+    return true;
+    /*
+    if (!mGltfLoaded) return false;
+
+    // fill local texture data structures
+    mSamplers.clear();
+    for (auto in_sampler : mGltfModel.samplers)
+    {
+        gltf_sampler sampler;
+        sampler.magFilter = in_sampler.magFilter > 0 ? in_sampler.magFilter : GL_LINEAR;
+        sampler.minFilter = in_sampler.minFilter > 0 ? in_sampler.minFilter : GL_LINEAR;;
+        sampler.wrapS     = in_sampler.wrapS;
+        sampler.wrapT     = in_sampler.wrapT;
+        sampler.name      = in_sampler.name; // unused
+        mSamplers.push_back(sampler);
+    }
+
+    mImages.clear();
+    for (auto in_image : mGltfModel.images)
+    {
+        gltf_image image;
+        image.numChannels     = in_image.component;
+        image.bytesPerChannel = in_image.bits >> 3;     // Convert bits to bytes
+        image.pixelType       = in_image.pixel_type;    // Maps exactly, i.e. TINYGLTF_COMPONENT_TYPE_UNSIGNED_BYTE == GL_UNSIGNED_BYTE, etc
+        image.size            = static_cast<U32>(in_image.image.size());
+        image.height          = in_image.height;
+        image.width           = in_image.width;
+        image.data            = in_image.image.data();
+
+        if (in_image.as_is)
+        {
+            LL_WARNS("GLTF_IMPORT") << "Unsupported image encoding" << LL_ENDL;
+            return false;
+        }
+
+        if (image.size != image.height * image.width * image.numChannels * image.bytesPerChannel)
+        {
+            LL_WARNS("GLTF_IMPORT") << "Image size error" << LL_ENDL;
+            return false;
+        }
+
+        mImages.push_back(image);
+    }
+
+    mTextures.clear();
+    for (auto in_tex : mGltfModel.textures)
+    {
+        gltf_texture tex;
+        tex.imageIdx   = in_tex.source;
+        tex.samplerIdx = in_tex.sampler;
+        tex.imageUuid.setNull();
+
+        if (tex.imageIdx >= mImages.size() || tex.samplerIdx >= mSamplers.size())
+        {
+            LL_WARNS("GLTF_IMPORT") << "Texture sampler/image index error" << LL_ENDL;
+            return false;
+        }
+
+        mTextures.push_back(tex);
+    }
+
+    // parse each material
+    for (tinygltf::Material gltf_material : mGltfModel.materials)
+    {
+        gltf_render_material mat;
+        mat.name = gltf_material.name;
+
+        tinygltf::PbrMetallicRoughness& pbr = gltf_material.pbrMetallicRoughness;
+        mat.hasPBR = true;  // Always true, for now
+
+        mat.baseColor.set(pbr.baseColorFactor.data());
+        mat.hasBaseTex = pbr.baseColorTexture.index >= 0;
+        mat.baseColorTexIdx = pbr.baseColorTexture.index;
+        mat.baseColorTexCoords = pbr.baseColorTexture.texCoord;
+
+        mat.metalness = pbr.metallicFactor;
+        mat.roughness = pbr.roughnessFactor;
+        mat.hasMRTex = pbr.metallicRoughnessTexture.index >= 0;
+        mat.metalRoughTexIdx = pbr.metallicRoughnessTexture.index;
+        mat.metalRoughTexCoords = pbr.metallicRoughnessTexture.texCoord;
+
+        mat.normalScale = gltf_material.normalTexture.scale;
+        mat.hasNormalTex = gltf_material.normalTexture.index >= 0;
+        mat.normalTexIdx = gltf_material.normalTexture.index;
+        mat.normalTexCoords = gltf_material.normalTexture.texCoord;
+
+        mat.occlusionScale = gltf_material.occlusionTexture.strength;
+        mat.hasOcclusionTex = gltf_material.occlusionTexture.index >= 0;
+        mat.occlusionTexIdx = gltf_material.occlusionTexture.index;
+        mat.occlusionTexCoords = gltf_material.occlusionTexture.texCoord;
+
+        mat.emissiveColor.set(gltf_material.emissiveFactor.data());
+        mat.hasEmissiveTex = gltf_material.emissiveTexture.index >= 0;
+        mat.emissiveTexIdx = gltf_material.emissiveTexture.index;
+        mat.emissiveTexCoords = gltf_material.emissiveTexture.texCoord;
+
+        mat.alphaMode = gltf_material.alphaMode;
+        mat.alphaMask = gltf_material.alphaCutoff;
+
+        if ((mat.hasNormalTex    && (mat.normalTexIdx     >= mTextures.size())) ||
+            (mat.hasOcclusionTex && (mat.occlusionTexIdx  >= mTextures.size())) ||
+            (mat.hasEmissiveTex  && (mat.emissiveTexIdx   >= mTextures.size())) ||
+            (mat.hasBaseTex      && (mat.baseColorTexIdx  >= mTextures.size())) ||
+            (mat.hasMRTex        && (mat.metalRoughTexIdx >= mTextures.size())))
+        {
+            LL_WARNS("GLTF_IMPORT") << "Texture resource index error" << LL_ENDL;
+            return false;
+        }
+
+        if ((mat.hasNormalTex    && (mat.normalTexCoords      > 2)) ||    // mesh can have up to 3 sets of UV
+            (mat.hasOcclusionTex && (mat.occlusionTexCoords   > 2)) ||
+            (mat.hasEmissiveTex  && (mat.emissiveTexCoords    > 2)) ||
+            (mat.hasBaseTex      && (mat.baseColorTexCoords   > 2)) ||
+            (mat.hasMRTex        && (mat.metalRoughTexCoords  > 2)))
+        {
+            LL_WARNS("GLTF_IMPORT") << "Image texcoord index error" << LL_ENDL;
+            return false;
+        }
+
+        mMaterials.push_back(mat);
+    }
+
+    return true;
+    */
+}
+
+// TODO: convert raw vertex buffers to UUIDs
+void LLGLTFLoader::uploadMeshes()
+{
+    //llassert(0);
+}
+
+// convert raw image buffers to texture UUIDs & assemble into a render material
+void LLGLTFLoader::uploadMaterials()
+{
+    for (gltf_render_material mat : mMaterials) // Initially 1 material per gltf file, but design for multiple
+    {
+        if (mat.hasBaseTex)
+        {
+            gltf_texture& gtex = mTextures[mat.baseColorTexIdx];
+            if (gtex.imageUuid.isNull())
+            {
+                gtex.imageUuid = imageBufferToTextureUUID(gtex);
+            }
+        }
+
+        if (mat.hasMRTex)
+        {
+            gltf_texture& gtex = mTextures[mat.metalRoughTexIdx];
+            if (gtex.imageUuid.isNull())
+            {
+                gtex.imageUuid = imageBufferToTextureUUID(gtex);
+            }
+        }
+
+        if (mat.hasNormalTex)
+        {
+            gltf_texture& gtex = mTextures[mat.normalTexIdx];
+            if (gtex.imageUuid.isNull())
+            {
+                gtex.imageUuid = imageBufferToTextureUUID(gtex);
+            }
+        }
+
+        if (mat.hasOcclusionTex)
+        {
+            gltf_texture& gtex = mTextures[mat.occlusionTexIdx];
+            if (gtex.imageUuid.isNull())
+            {
+                gtex.imageUuid = imageBufferToTextureUUID(gtex);
+            }
+        }
+
+        if (mat.hasEmissiveTex)
+        {
+            gltf_texture& gtex = mTextures[mat.emissiveTexIdx];
+            if (gtex.imageUuid.isNull())
+            {
+                gtex.imageUuid = imageBufferToTextureUUID(gtex);
+            }
+        }
+    }
+}
+
+LLUUID LLGLTFLoader::imageBufferToTextureUUID(const gltf_texture& tex)
+{
+    //gltf_image& image = mImages[tex.imageIdx];
+    //gltf_sampler& sampler = mSamplers[tex.samplerIdx];
+
+    // fill an LLSD container with image+sampler data
+
+    // upload texture
+
+    // retrieve UUID
+
+    return LLUUID::null;
+}
diff --git a/indra/newview/gltf/llgltfloader.h b/indra/newview/gltf/llgltfloader.h
new file mode 100644
index 0000000000..3b7147f588
--- /dev/null
+++ b/indra/newview/gltf/llgltfloader.h
@@ -0,0 +1,209 @@
+/**
+ * @file LLGLTFLoader.h
+ * @brief LLGLTFLoader class definition
+ *
+ * $LicenseInfo:firstyear=2022&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2022, 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
+ * $/LicenseInfo$
+ */
+
+#ifndef LL_LLGLTFLoader_H
+#define LL_LLGLTFLoader_H
+
+#include "tinygltf/tiny_gltf.h"
+
+#include "asset.h"
+
+#include "llglheaders.h"
+#include "llmodelloader.h"
+
+// gltf_* structs are temporary, used to organize the subset of data that eventually goes into the material LLSD
+
+class gltf_sampler
+{
+public:
+    // Uses GL enums
+    S32 minFilter;      // GL_NEAREST, GL_LINEAR, GL_NEAREST_MIPMAP_NEAREST, GL_LINEAR_MIPMAP_NEAREST, GL_NEAREST_MIPMAP_LINEAR or GL_LINEAR_MIPMAP_LINEAR
+    S32 magFilter;      // GL_NEAREST or GL_LINEAR
+    S32 wrapS;          // GL_CLAMP_TO_EDGE, GL_MIRRORED_REPEAT or GL_REPEAT
+    S32 wrapT;          // GL_CLAMP_TO_EDGE, GL_MIRRORED_REPEAT or GL_REPEAT
+    //S32 wrapR;        // Found in some sample files, but not part of glTF 2.0 spec. Ignored.
+    std::string name;   // optional, currently unused
+    // extensions and extras are sampler optional fields that we don't support - at least initially
+};
+
+class gltf_image
+{
+public:// Note that glTF images are defined with row 0 at the top (opposite of OpenGL)
+    U8* data;               // ptr to decoded image data
+    U32 size;               // in bytes, regardless of channel width
+    U32 width;
+    U32 height;
+    U32 numChannels;        // range 1..4
+    U32 bytesPerChannel;    // converted from gltf "bits", expects only 8, 16 or 32 as input
+    U32 pixelType;          // one of (TINYGLTF_COMPONENT_TYPE)_UNSIGNED_BYTE, _UNSIGNED_SHORT, _UNSIGNED_INT, or _FLOAT
+};
+
+class gltf_texture
+{
+public:
+    U32 imageIdx;
+    U32 samplerIdx;
+    LLUUID imageUuid = LLUUID::null;
+};
+
+class gltf_render_material
+{
+public:
+    std::string name;
+
+    // scalar values
+    LLColor4    baseColor;      // linear encoding. Multiplied with vertex color, if present.
+    double      metalness;
+    double      roughness;
+    double      normalScale;    // scale applies only to X,Y components of normal
+    double      occlusionScale; // strength multiplier for occlusion
+    LLColor4    emissiveColor;  // emissive mulitiplier, assumed linear encoding (spec 2.0 is silent)
+    std::string alphaMode;      // "OPAQUE", "MASK" or "BLEND"
+    double      alphaMask;      // alpha cut-off
+
+    // textures
+    U32 baseColorTexIdx;    // always sRGB encoded
+    U32 metalRoughTexIdx;   // always linear, roughness in G channel, metalness in B channel
+    U32 normalTexIdx;       // linear, valid range R[0-1], G[0-1], B[0.5-1]. Normal = texel * 2 - vec3(1.0)
+    U32 occlusionTexIdx;    // linear, occlusion in R channel, 0 meaning fully occluded, 1 meaning not occluded
+    U32 emissiveTexIdx;     // always stored as sRGB, in nits (candela / meter^2)
+
+    // texture coordinates
+    U32 baseColorTexCoords;
+    U32 metalRoughTexCoords;
+    U32 normalTexCoords;
+    U32 occlusionTexCoords;
+    U32 emissiveTexCoords;
+
+    // TODO: Add traditional (diffuse, normal, specular) UUIDs here, or add this struct to LL_TextureEntry??
+
+    bool        hasPBR;
+    bool        hasBaseTex, hasMRTex, hasNormalTex, hasOcclusionTex, hasEmissiveTex;
+
+    // This field is populated after upload
+    LLUUID      material_uuid = LLUUID::null;
+
+};
+
+class gltf_mesh
+{
+public:
+    std::string name;
+
+    // TODO add mesh import DJH 2022-04
+
+};
+
+class LLGLTFLoader : public LLModelLoader
+{
+  public:
+    typedef std::map<std::string, LLImportMaterial> material_map;
+
+    LLGLTFLoader(std::string filename,
+                    S32                                 lod,
+                    LLModelLoader::load_callback_t      load_cb,
+                    LLModelLoader::joint_lookup_func_t  joint_lookup_func,
+                    LLModelLoader::texture_load_func_t  texture_load_func,
+                    LLModelLoader::state_callback_t     state_cb,
+                    void *                              opaque_userdata,
+                    JointTransformMap &                 jointTransformMap,
+                    JointNameSet &                      jointsFromNodes,
+                    std::map<std::string, std::string> &jointAliasMap,
+                    U32                                 maxJointsPerMesh,
+                    U32                                 modelLimit); //,
+                    //bool                                preprocess );
+    virtual ~LLGLTFLoader();
+
+    virtual bool OpenFile(const std::string &filename);
+
+protected:
+    LL::GLTF::Asset mGLTFAsset;
+    tinygltf::Model mGltfModel;
+    bool            mGltfLoaded;
+    bool            mMeshesLoaded;
+    bool            mMaterialsLoaded;
+
+    std::vector<gltf_mesh>              mMeshes;
+    std::vector<gltf_render_material>   mMaterials;
+
+    std::vector<gltf_texture>           mTextures;
+    std::vector<gltf_image>             mImages;
+    std::vector<gltf_sampler>           mSamplers;
+
+private:
+    bool parseMeshes();
+    void uploadMeshes();
+    bool parseMaterials();
+    void uploadMaterials();
+    bool populateModelFromMesh(LLModel* pModel, const LL::GLTF::Mesh &mesh, material_map& mats);
+    LLUUID imageBufferToTextureUUID(const gltf_texture& tex);
+
+    //    bool mPreprocessGLTF;
+
+    /*  Below inherited from dae loader - unknown if/how useful here
+
+    void processElement(gltfElement *element, bool &badElement, GLTF *gltf);
+    void processGltfModel(LLModel *model, GLTF *gltf, gltfElement *pRoot, gltfMesh *mesh, gltfSkin *skin);
+
+    material_map     getMaterials(LLModel *model, gltfInstance_geometry *instance_geo, GLTF *gltf);
+    LLImportMaterial profileToMaterial(gltfProfile_COMMON *material, GLTF *gltf);
+    LLColor4         getGltfColor(gltfElement *element);
+
+    gltfElement *getChildFromElement(gltfElement *pElement, std::string const &name);
+
+    bool isNodeAJoint(gltfNode *pNode);
+    void processJointNode(gltfNode *pNode, std::map<std::string, LLMatrix4> &jointTransforms);
+    void extractTranslation(gltfTranslate *pTranslate, LLMatrix4 &transform);
+    void extractTranslationViaElement(gltfElement *pTranslateElement, LLMatrix4 &transform);
+    void extractTranslationViaSID(gltfElement *pElement, LLMatrix4 &transform);
+    void buildJointToNodeMappingFromScene(gltfElement *pRoot);
+    void processJointToNodeMapping(gltfNode *pNode);
+    void processChildJoints(gltfNode *pParentNode);
+
+    bool verifyCount(int expected, int result);
+
+    // Verify that a controller matches vertex counts
+    bool verifyController(gltfController *pController);
+
+    static bool addVolumeFacesFromGltfMesh(LLModel *model, gltfMesh *mesh, LLSD &log_msg);
+    static bool createVolumeFacesFromGltfMesh(LLModel *model, gltfMesh *mesh);
+
+    static LLModel *loadModelFromGltfMesh(gltfMesh *mesh);
+
+    // Loads a mesh breaking it into one or more models as necessary
+    // to get around volume face limitations while retaining >8 materials
+    //
+    bool loadModelsFromGltfMesh(gltfMesh *mesh, std::vector<LLModel *> &models_out, U32 submodel_limit);
+
+    static std::string getElementLabel(gltfElement *element);
+    static size_t      getSuffixPosition(std::string label);
+    static std::string getLodlessLabel(gltfElement *element);
+
+    static std::string preprocessGLTF(std::string filename);
+    */
+
+};
+#endif  // LL_LLGLTFLLOADER_H
diff --git a/indra/newview/llfilepicker.cpp b/indra/newview/llfilepicker.cpp
index 716e6cd9e3..09a2206cd7 100644
--- a/indra/newview/llfilepicker.cpp
+++ b/indra/newview/llfilepicker.cpp
@@ -59,7 +59,7 @@ LLFilePicker LLFilePicker::sInstance;
 #define XML_FILTER L"XML files (*.xml)\0*.xml\0"
 #define SLOBJECT_FILTER L"Objects (*.slobject)\0*.slobject\0"
 #define RAW_FILTER L"RAW files (*.raw)\0*.raw\0"
-#define MODEL_FILTER L"Model files (*.dae)\0*.dae\0"
+#define MODEL_FILTER L"Model files (*.dae, *.gltf, *.glb)\0*.dae;*.gltf;*.glb\0"
 #define MATERIAL_FILTER L"GLTF Files (*.gltf; *.glb)\0*.gltf;*.glb\0"
 #define HDRI_FILTER L"HDRI Files (*.exr)\0*.exr\0"
 #define MATERIAL_TEXTURES_FILTER L"GLTF Import (*.gltf; *.glb; *.tga; *.bmp; *.jpg; *.jpeg; *.png)\0*.gltf;*.glb;*.tga;*.bmp;*.jpg;*.jpeg;*.png\0"
diff --git a/indra/newview/llmodelpreview.cpp b/indra/newview/llmodelpreview.cpp
index 5a8fd299bf..14d23b73c9 100644
--- a/indra/newview/llmodelpreview.cpp
+++ b/indra/newview/llmodelpreview.cpp
@@ -30,7 +30,7 @@
 
 #include "llmodelloader.h"
 #include "lldaeloader.h"
-#include "llgltfloader.h"
+#include "gltf/llgltfloader.h"
 #include "llfloatermodelpreview.h"
 
 #include "llagent.h"