add assimp submodule

1 files changed, 2069 insertions, 0 deletions

diff --git a/src/mesh/assimp-master/code/AssetLib/glTF2/glTF2Asset.inl b/src/mesh/assimp-master/code/AssetLib/glTF2/glTF2Asset.inl
new file mode 100644
index 0000000..ec481a7
--- /dev/null
+++ b/src/mesh/assimp-master/code/AssetLib/glTF2/glTF2Asset.inl
@@ -0,0 +1,2069 @@
+/*
+Open Asset Import Library (assimp)
+----------------------------------------------------------------------
+
+Copyright (c) 2006-2022, assimp team
+
+All rights reserved.
+
+Redistribution and use of this software in source and binary forms,
+with or without modification, are permitted provided that the
+following conditions are met:
+
+* Redistributions of source code must retain the above
+copyright notice, this list of conditions and the
+following disclaimer.
+
+* Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the
+following disclaimer in the documentation and/or other
+materials provided with the distribution.
+
+* Neither the name of the assimp team, nor the names of its
+contributors may be used to endorse or promote products
+derived from this software without specific prior
+written permission of the assimp team.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+----------------------------------------------------------------------
+*/
+
+#include "AssetLib/glTF/glTFCommon.h"
+
+#include <assimp/MemoryIOWrapper.h>
+#include <assimp/StringUtils.h>
+#include <assimp/DefaultLogger.hpp>
+#include <assimp/Base64.hpp>
+
+// clang-format off
+#ifdef ASSIMP_ENABLE_DRACO
+
+// Google draco library headers spew many warnings. Bad Google, no cookie
+#   if _MSC_VER
+#       pragma warning(push)
+#       pragma warning(disable : 4018) // Signed/unsigned mismatch
+#       pragma warning(disable : 4804) // Unsafe use of type 'bool'
+#   elif defined(__clang__)
+#       pragma clang diagnostic push
+#       pragma clang diagnostic ignored "-Wsign-compare"
+#   elif defined(__GNUC__)
+#       pragma GCC diagnostic push
+#       if (__GNUC__ > 4)
+#           pragma GCC diagnostic ignored "-Wbool-compare"
+#       endif
+#   pragma GCC diagnostic ignored "-Wsign-compare"
+#endif
+
+#include "draco/compression/decode.h"
+#include "draco/core/decoder_buffer.h"
+
+#if _MSC_VER
+#   pragma warning(pop)
+#elif defined(__clang__)
+#   pragma clang diagnostic pop
+#elif defined(__GNUC__)
+#   pragma GCC diagnostic pop
+#endif
+#ifndef DRACO_MESH_COMPRESSION_SUPPORTED
+#   error glTF: KHR_draco_mesh_compression: draco library must have DRACO_MESH_COMPRESSION_SUPPORTED
+#endif
+#endif
+// clang-format on
+
+using namespace Assimp;
+using namespace glTFCommon;
+
+namespace glTF2 {
+
+namespace {
+
+//
+// JSON Value reading helpers
+//
+inline CustomExtension ReadExtensions(const char *name, Value &obj) {
+    CustomExtension ret;
+    ret.name = name;
+    if (obj.IsObject()) {
+        ret.mValues.isPresent = true;
+        for (auto it = obj.MemberBegin(); it != obj.MemberEnd(); ++it) {
+            auto &val = it->value;
+            ret.mValues.value.push_back(ReadExtensions(it->name.GetString(), val));
+        }
+    } else if (obj.IsArray()) {
+        ret.mValues.value.reserve(obj.Size());
+        ret.mValues.isPresent = true;
+        for (unsigned int i = 0; i < obj.Size(); ++i) {
+            ret.mValues.value.push_back(ReadExtensions(name, obj[i]));
+        }
+    } else if (obj.IsNumber()) {
+        if (obj.IsUint64()) {
+            ret.mUint64Value.value = obj.GetUint64();
+            ret.mUint64Value.isPresent = true;
+        } else if (obj.IsInt64()) {
+            ret.mInt64Value.value = obj.GetInt64();
+            ret.mInt64Value.isPresent = true;
+        } else if (obj.IsDouble()) {
+            ret.mDoubleValue.value = obj.GetDouble();
+            ret.mDoubleValue.isPresent = true;
+        }
+    } else if (obj.IsString()) {
+        ReadValue(obj, ret.mStringValue);
+        ret.mStringValue.isPresent = true;
+    } else if (obj.IsBool()) {
+        ret.mBoolValue.value = obj.GetBool();
+        ret.mBoolValue.isPresent = true;
+    }
+    return ret;
+}
+
+inline void CopyData(size_t count, const uint8_t *src, size_t src_stride,
+        uint8_t *dst, size_t dst_stride) {
+    if (src_stride == dst_stride) {
+        memcpy(dst, src, count * src_stride);
+        return;
+    }
+
+    size_t sz = std::min(src_stride, dst_stride);
+    for (size_t i = 0; i < count; ++i) {
+        memcpy(dst, src, sz);
+        if (sz < dst_stride) {
+            memset(dst + sz, 0, dst_stride - sz);
+        }
+        src += src_stride;
+        dst += dst_stride;
+    }
+}
+
+void SetVector(vec4 &v, const float (&in)[4]) {
+    v[0] = in[0];
+    v[1] = in[1];
+    v[2] = in[2];
+    v[3] = in[3];
+}
+
+void SetVector(vec3 &v, const float (&in)[3]) {
+    v[0] = in[0];
+    v[1] = in[1];
+    v[2] = in[2];
+}
+
+template <int N>
+inline int Compare(const char *attr, const char (&str)[N]) {
+    return (strncmp(attr, str, N - 1) == 0) ? N - 1 : 0;
+}
+
+#if _MSC_VER
+#pragma warning(push)
+#pragma warning(disable : 4706)
+#endif // _MSC_VER
+
+inline bool GetAttribVector(Mesh::Primitive &p, const char *attr, Mesh::AccessorList *&v, int &pos) {
+    if ((pos = Compare(attr, "POSITION"))) {
+        v = &(p.attributes.position);
+    } else if ((pos = Compare(attr, "NORMAL"))) {
+        v = &(p.attributes.normal);
+    } else if ((pos = Compare(attr, "TANGENT"))) {
+        v = &(p.attributes.tangent);
+    } else if ((pos = Compare(attr, "TEXCOORD"))) {
+        v = &(p.attributes.texcoord);
+    } else if ((pos = Compare(attr, "COLOR"))) {
+        v = &(p.attributes.color);
+    } else if ((pos = Compare(attr, "JOINT"))) {
+        v = &(p.attributes.joint);
+    } else if ((pos = Compare(attr, "JOINTMATRIX"))) {
+        v = &(p.attributes.jointmatrix);
+    } else if ((pos = Compare(attr, "WEIGHT"))) {
+        v = &(p.attributes.weight);
+    } else
+        return false;
+    return true;
+}
+
+inline bool GetAttribTargetVector(Mesh::Primitive &p, const int targetIndex, const char *attr, Mesh::AccessorList *&v, int &pos) {
+    if ((pos = Compare(attr, "POSITION"))) {
+        v = &(p.targets[targetIndex].position);
+    } else if ((pos = Compare(attr, "NORMAL"))) {
+        v = &(p.targets[targetIndex].normal);
+    } else if ((pos = Compare(attr, "TANGENT"))) {
+        v = &(p.targets[targetIndex].tangent);
+    } else
+        return false;
+    return true;
+}
+
+} // namespace
+
+inline Value *Object::FindString(Value &val, const char *memberId) {
+    return FindStringInContext(val, memberId, id.c_str(), name.c_str());
+}
+
+inline Value *Object::FindNumber(Value &val, const char *memberId) {
+    return FindNumberInContext(val, memberId, id.c_str(), name.c_str());
+}
+
+inline Value *Object::FindUInt(Value &val, const char *memberId) {
+    return FindUIntInContext(val, memberId, id.c_str(), name.c_str());
+}
+
+inline Value *Object::FindArray(Value &val, const char *memberId) {
+    return FindArrayInContext(val, memberId, id.c_str(), name.c_str());
+}
+
+inline Value *Object::FindObject(Value &val, const char *memberId) {
+    return FindObjectInContext(val, memberId, id.c_str(), name.c_str());
+}
+
+inline Value *Object::FindExtension(Value &val, const char *extensionId) {
+    return FindExtensionInContext(val, extensionId, id.c_str(), name.c_str());
+}
+
+inline void Object::ReadExtensions(Value &val) {
+    if (Value *curExtensions = FindObject(val, "extensions")) {
+        this->customExtensions = glTF2::ReadExtensions("extensions", *curExtensions);
+    }
+}
+
+inline void Object::ReadExtras(Value &val) {
+    if (Value *curExtras = FindObject(val, "extras")) {
+        this->extras = glTF2::ReadExtensions("extras", *curExtras);
+    }
+}
+
+#ifdef ASSIMP_ENABLE_DRACO
+
+template <typename T>
+inline void CopyFaceIndex_Draco(Buffer &decodedIndexBuffer, const draco::Mesh &draco_mesh) {
+    const size_t faceStride = sizeof(T) * 3;
+    for (draco::FaceIndex f(0); f < draco_mesh.num_faces(); ++f) {
+        const draco::Mesh::Face &face = draco_mesh.face(f);
+        T indices[3] = { static_cast<T>(face[0].value()), static_cast<T>(face[1].value()), static_cast<T>(face[2].value()) };
+        memcpy(decodedIndexBuffer.GetPointer() + (f.value() * faceStride), &indices[0], faceStride);
+    }
+}
+
+inline void SetDecodedIndexBuffer_Draco(const draco::Mesh &dracoMesh, Mesh::Primitive &prim) {
+    if (!prim.indices || dracoMesh.num_faces() == 0)
+        return;
+
+    // Create a decoded Index buffer (if there is one)
+    size_t componentBytes = prim.indices->GetBytesPerComponent();
+
+    std::unique_ptr<Buffer> decodedIndexBuffer(new Buffer());
+    decodedIndexBuffer->Grow(dracoMesh.num_faces() * 3 * componentBytes);
+
+    // If accessor uses the same size as draco implementation, copy the draco buffer directly
+
+    // Usually uint32_t but shouldn't assume
+    if (sizeof(dracoMesh.face(draco::FaceIndex(0))[0]) == componentBytes) {
+        memcpy(decodedIndexBuffer->GetPointer(), &dracoMesh.face(draco::FaceIndex(0))[0], decodedIndexBuffer->byteLength);
+        return;
+    }
+
+    // Not same size, convert
+    switch (componentBytes) {
+    case sizeof(uint32_t):
+        CopyFaceIndex_Draco<uint32_t>(*decodedIndexBuffer, dracoMesh);
+        break;
+    case sizeof(uint16_t):
+        CopyFaceIndex_Draco<uint16_t>(*decodedIndexBuffer, dracoMesh);
+        break;
+    case sizeof(uint8_t):
+        CopyFaceIndex_Draco<uint8_t>(*decodedIndexBuffer, dracoMesh);
+        break;
+    default:
+        ai_assert(false);
+        break;
+    }
+
+    // Assign this alternate data buffer to the accessor
+    prim.indices->decodedBuffer.swap(decodedIndexBuffer);
+}
+
+template <typename T>
+static bool GetAttributeForAllPoints_Draco(const draco::Mesh &dracoMesh,
+        const draco::PointAttribute &dracoAttribute,
+        Buffer &outBuffer) {
+    size_t byteOffset = 0;
+    T values[4] = { 0, 0, 0, 0 };
+    for (draco::PointIndex i(0); i < dracoMesh.num_points(); ++i) {
+        const draco::AttributeValueIndex val_index = dracoAttribute.mapped_index(i);
+        if (!dracoAttribute.ConvertValue<T>(val_index, dracoAttribute.num_components(), values)) {
+            return false;
+        }
+
+        memcpy(outBuffer.GetPointer() + byteOffset, &values[0], sizeof(T) * dracoAttribute.num_components());
+        byteOffset += sizeof(T) * dracoAttribute.num_components();
+    }
+
+    return true;
+}
+
+inline void SetDecodedAttributeBuffer_Draco(const draco::Mesh &dracoMesh, uint32_t dracoAttribId, Accessor &accessor) {
+    // Create decoded buffer
+    const draco::PointAttribute *pDracoAttribute = dracoMesh.GetAttributeByUniqueId(dracoAttribId);
+    if (pDracoAttribute == nullptr) {
+        throw DeadlyImportError("GLTF: Invalid draco attribute id: ", dracoAttribId);
+    }
+
+    size_t componentBytes = accessor.GetBytesPerComponent();
+
+    std::unique_ptr<Buffer> decodedAttribBuffer(new Buffer());
+    decodedAttribBuffer->Grow(dracoMesh.num_points() * pDracoAttribute->num_components() * componentBytes);
+
+    switch (accessor.componentType) {
+    case ComponentType_BYTE:
+        GetAttributeForAllPoints_Draco<int8_t>(dracoMesh, *pDracoAttribute, *decodedAttribBuffer);
+        break;
+    case ComponentType_UNSIGNED_BYTE:
+        GetAttributeForAllPoints_Draco<uint8_t>(dracoMesh, *pDracoAttribute, *decodedAttribBuffer);
+        break;
+    case ComponentType_SHORT:
+        GetAttributeForAllPoints_Draco<int16_t>(dracoMesh, *pDracoAttribute, *decodedAttribBuffer);
+        break;
+    case ComponentType_UNSIGNED_SHORT:
+        GetAttributeForAllPoints_Draco<uint16_t>(dracoMesh, *pDracoAttribute, *decodedAttribBuffer);
+        break;
+    case ComponentType_UNSIGNED_INT:
+        GetAttributeForAllPoints_Draco<uint32_t>(dracoMesh, *pDracoAttribute, *decodedAttribBuffer);
+        break;
+    case ComponentType_FLOAT:
+        GetAttributeForAllPoints_Draco<float>(dracoMesh, *pDracoAttribute, *decodedAttribBuffer);
+        break;
+    default:
+        ai_assert(false);
+        break;
+    }
+
+    // Assign this alternate data buffer to the accessor
+    accessor.decodedBuffer.swap(decodedAttribBuffer);
+}
+
+#endif // ASSIMP_ENABLE_DRACO
+
+//
+// LazyDict methods
+//
+
+template <class T>
+inline LazyDict<T>::LazyDict(Asset &asset, const char *dictId, const char *extId) :
+        mDictId(dictId),
+        mExtId(extId),
+        mDict(0),
+        mAsset(asset) {
+    asset.mDicts.push_back(this); // register to the list of dictionaries
+}
+
+template <class T>
+inline LazyDict<T>::~LazyDict() {
+    for (size_t i = 0; i < mObjs.size(); ++i) {
+        delete mObjs[i];
+    }
+}
+
+template <class T>
+inline void LazyDict<T>::AttachToDocument(Document &doc) {
+    Value *container = nullptr;
+    const char *context = nullptr;
+
+    if (mExtId) {
+        if (Value *exts = FindObject(doc, "extensions")) {
+            container = FindObjectInContext(*exts, mExtId, "extensions");
+            context = mExtId;
+        }
+    } else {
+        container = &doc;
+        context = "the document";
+    }
+
+    if (container) {
+        mDict = FindArrayInContext(*container, mDictId, context);
+    }
+}
+
+template <class T>
+inline void LazyDict<T>::DetachFromDocument() {
+    mDict = nullptr;
+}
+
+template <class T>
+unsigned int LazyDict<T>::Remove(const char *id) {
+    id = T::TranslateId(mAsset, id);
+
+    typename IdDict::iterator objIt = mObjsById.find(id);
+
+    if (objIt == mObjsById.end()) {
+        throw DeadlyExportError("GLTF: Object with id \"" + std::string(id) + "\" is not found");
+    }
+
+    const unsigned int index = objIt->second;
+
+    mAsset.mUsedIds[id] = false;
+    mObjsById.erase(id);
+    mObjsByOIndex.erase(index);
+    delete mObjs[index];
+    mObjs.erase(mObjs.begin() + index);
+
+    //update index of object in mObjs;
+    for (unsigned int i = index; i < mObjs.size(); ++i) {
+        T *obj = mObjs[i];
+
+        obj->index = i;
+    }
+
+    for (IdDict::iterator it = mObjsById.begin(); it != mObjsById.end(); ++it) {
+        if (it->second <= index) {
+            continue;
+        }
+
+        mObjsById[it->first] = it->second - 1;
+    }
+
+    for (Dict::iterator it = mObjsByOIndex.begin(); it != mObjsByOIndex.end(); ++it) {
+        if (it->second <= index) {
+            continue;
+        }
+
+        mObjsByOIndex[it->first] = it->second - 1;
+    }
+
+    return index;
+}
+
+template <class T>
+Ref<T> LazyDict<T>::Retrieve(unsigned int i) {
+
+    typename Dict::iterator it = mObjsByOIndex.find(i);
+    if (it != mObjsByOIndex.end()) { // already created?
+        return Ref<T>(mObjs, it->second);
+    }
+
+    // read it from the JSON object
+    if (!mDict) {
+        throw DeadlyImportError("GLTF: Missing section \"", mDictId, "\"");
+    }
+
+    if (!mDict->IsArray()) {
+        throw DeadlyImportError("GLTF: Field \"", mDictId, "\"  is not an array");
+    }
+
+    if (i >= mDict->Size()) {
+        throw DeadlyImportError("GLTF: Array index ", i, " is out of bounds (", mDict->Size(), ") for \"", mDictId, "\"");
+    }
+
+    Value &obj = (*mDict)[i];
+
+    if (!obj.IsObject()) {
+        throw DeadlyImportError("GLTF: Object at index ", i, " in array \"", mDictId, "\" is not a JSON object");
+    }
+
+    if (mRecursiveReferenceCheck.find(i) != mRecursiveReferenceCheck.end()) {
+        throw DeadlyImportError("GLTF: Object at index ", i, " in array \"", mDictId, "\" has recursive reference to itself");
+    }
+    mRecursiveReferenceCheck.insert(i);
+
+    // Unique ptr prevents memory leak in case of Read throws an exception
+    auto inst = std::unique_ptr<T>(new T());
+    // Try to make this human readable so it can be used in error messages.
+    inst->id = std::string(mDictId) + "[" + ai_to_string(i) + "]";
+    inst->oIndex = i;
+    ReadMember(obj, "name", inst->name);
+    inst->Read(obj, mAsset);
+    inst->ReadExtensions(obj);
+    inst->ReadExtras(obj);
+
+    Ref<T> result = Add(inst.release());
+    mRecursiveReferenceCheck.erase(i);
+    return result;
+}
+
+template <class T>
+Ref<T> LazyDict<T>::Get(unsigned int i) {
+    return Ref<T>(mObjs, i);
+}
+
+template <class T>
+Ref<T> LazyDict<T>::Get(const char *id) {
+    id = T::TranslateId(mAsset, id);
+
+    typename IdDict::iterator it = mObjsById.find(id);
+    if (it != mObjsById.end()) { // already created?
+        return Ref<T>(mObjs, it->second);
+    }
+
+    return Ref<T>();
+}
+
+template <class T>
+Ref<T> LazyDict<T>::Add(T *obj) {
+    unsigned int idx = unsigned(mObjs.size());
+    mObjs.push_back(obj);
+    mObjsByOIndex[obj->oIndex] = idx;
+    mObjsById[obj->id] = idx;
+    mAsset.mUsedIds[obj->id] = true;
+    return Ref<T>(mObjs, idx);
+}
+
+template <class T>
+Ref<T> LazyDict<T>::Create(const char *id) {
+    Asset::IdMap::iterator it = mAsset.mUsedIds.find(id);
+    if (it != mAsset.mUsedIds.end()) {
+        throw DeadlyImportError("GLTF: two objects with the same ID exist");
+    }
+    T *inst = new T();
+    unsigned int idx = unsigned(mObjs.size());
+    inst->id = id;
+    inst->index = idx;
+    inst->oIndex = idx;
+    return Add(inst);
+}
+
+//
+// glTF dictionary objects methods
+//
+inline Buffer::Buffer() :
+        byteLength(0),
+        type(Type_arraybuffer),
+        EncodedRegion_Current(nullptr),
+        mIsSpecial(false) {}
+
+inline Buffer::~Buffer() {
+    for (SEncodedRegion *reg : EncodedRegion_List)
+        delete reg;
+}
+
+inline const char *Buffer::TranslateId(Asset & /*r*/, const char *id) {
+    return id;
+}
+
+inline void Buffer::Read(Value &obj, Asset &r) {
+    size_t statedLength = MemberOrDefault<size_t>(obj, "byteLength", 0);
+    byteLength = statedLength;
+
+    Value *it = FindString(obj, "uri");
+    if (!it) {
+        if (statedLength > 0) {
+            throw DeadlyImportError("GLTF: buffer with non-zero length missing the \"uri\" attribute");
+        }
+        return;
+    }
+
+    const char *uri = it->GetString();
+
+    glTFCommon::Util::DataURI dataURI;
+    if (ParseDataURI(uri, it->GetStringLength(), dataURI)) {
+        if (dataURI.base64) {
+            uint8_t *data = nullptr;
+            this->byteLength = Base64::Decode(dataURI.data, dataURI.dataLength, data);
+            this->mData.reset(data, std::default_delete<uint8_t[]>());
+
+            if (statedLength > 0 && this->byteLength != statedLength) {
+                throw DeadlyImportError("GLTF: buffer \"", id, "\", expected ", ai_to_string(statedLength),
+                        " bytes, but found ", ai_to_string(dataURI.dataLength));
+            }
+        } else { // assume raw data
+            if (statedLength != dataURI.dataLength) {
+                throw DeadlyImportError("GLTF: buffer \"", id, "\", expected ", ai_to_string(statedLength),
+                        " bytes, but found ", ai_to_string(dataURI.dataLength));
+            }
+
+            this->mData.reset(new uint8_t[dataURI.dataLength], std::default_delete<uint8_t[]>());
+            memcpy(this->mData.get(), dataURI.data, dataURI.dataLength);
+        }
+    } else { // Local file
+        if (byteLength > 0) {
+            std::string dir = !r.mCurrentAssetDir.empty() ? (r.mCurrentAssetDir.back() == '/' ? r.mCurrentAssetDir : r.mCurrentAssetDir + '/') : "";
+
+            IOStream *file = r.OpenFile(dir + uri, "rb");
+            if (file) {
+                bool ok = LoadFromStream(*file, byteLength);
+                delete file;
+
+                if (!ok)
+                    throw DeadlyImportError("GLTF: error while reading referenced file \"", uri, "\"");
+            } else {
+                throw DeadlyImportError("GLTF: could not open referenced file \"", uri, "\"");
+            }
+        }
+    }
+}
+
+inline bool Buffer::LoadFromStream(IOStream &stream, size_t length, size_t baseOffset) {
+    byteLength = length ? length : stream.FileSize();
+
+    if (byteLength > stream.FileSize()) {
+        throw DeadlyImportError("GLTF: Invalid byteLength exceeds size of actual data.");
+    }
+
+    if (baseOffset) {
+        stream.Seek(baseOffset, aiOrigin_SET);
+    }
+
+    mData.reset(new uint8_t[byteLength], std::default_delete<uint8_t[]>());
+
+    if (stream.Read(mData.get(), byteLength, 1) != 1) {
+        return false;
+    }
+    return true;
+}
+
+inline void Buffer::EncodedRegion_Mark(const size_t pOffset, const size_t pEncodedData_Length, uint8_t *pDecodedData, const size_t pDecodedData_Length, const std::string &pID) {
+    // Check pointer to data
+    if (pDecodedData == nullptr) throw DeadlyImportError("GLTF: for marking encoded region pointer to decoded data must be provided.");
+
+    // Check offset
+    if (pOffset > byteLength) {
+        const uint8_t val_size = 32;
+
+        char val[val_size];
+
+        ai_snprintf(val, val_size, AI_SIZEFMT, pOffset);
+        throw DeadlyImportError("GLTF: incorrect offset value (", val, ") for marking encoded region.");
+    }
+
+    // Check length
+    if ((pOffset + pEncodedData_Length) > byteLength) {
+        const uint8_t val_size = 64;
+
+        char val[val_size];
+
+        ai_snprintf(val, val_size, AI_SIZEFMT "/" AI_SIZEFMT, pOffset, pEncodedData_Length);
+        throw DeadlyImportError("GLTF: encoded region with offset/length (", val, ") is out of range.");
+    }
+
+    // Add new region
+    EncodedRegion_List.push_back(new SEncodedRegion(pOffset, pEncodedData_Length, pDecodedData, pDecodedData_Length, pID));
+    // And set new value for "byteLength"
+    byteLength += (pDecodedData_Length - pEncodedData_Length);
+}
+
+inline void Buffer::EncodedRegion_SetCurrent(const std::string &pID) {
+    if ((EncodedRegion_Current != nullptr) && (EncodedRegion_Current->ID == pID)) {
+        return;
+    }
+
+    for (SEncodedRegion *reg : EncodedRegion_List) {
+        if (reg->ID == pID) {
+            EncodedRegion_Current = reg;
+            return;
+        }
+    }
+
+    throw DeadlyImportError("GLTF: EncodedRegion with ID: \"", pID, "\" not found.");
+}
+
+inline bool Buffer::ReplaceData(const size_t pBufferData_Offset, const size_t pBufferData_Count, const uint8_t *pReplace_Data, const size_t pReplace_Count) {
+
+    if ((pBufferData_Count == 0) || (pReplace_Count == 0) || (pReplace_Data == nullptr)) {
+        return false;
+    }
+
+    const size_t new_data_size = byteLength + pReplace_Count - pBufferData_Count;
+    uint8_t *new_data = new uint8_t[new_data_size];
+    // Copy data which place before replacing part.
+    ::memcpy(new_data, mData.get(), pBufferData_Offset);
+    // Copy new data.
+    ::memcpy(&new_data[pBufferData_Offset], pReplace_Data, pReplace_Count);
+    // Copy data which place after replacing part.
+    ::memcpy(&new_data[pBufferData_Offset + pReplace_Count], &mData.get()[pBufferData_Offset + pBufferData_Count], pBufferData_Offset);
+    // Apply new data
+    mData.reset(new_data, std::default_delete<uint8_t[]>());
+    byteLength = new_data_size;
+
+    return true;
+}
+
+inline bool Buffer::ReplaceData_joint(const size_t pBufferData_Offset, const size_t pBufferData_Count, const uint8_t *pReplace_Data, const size_t pReplace_Count) {
+    if ((pBufferData_Count == 0) || (pReplace_Count == 0) || (pReplace_Data == nullptr)) {
+        return false;
+    }
+
+    const size_t new_data_size = byteLength + pReplace_Count - pBufferData_Count;
+    uint8_t *new_data = new uint8_t[new_data_size];
+    // Copy data which place before replacing part.
+    memcpy(new_data, mData.get(), pBufferData_Offset);
+    // Copy new data.
+    memcpy(&new_data[pBufferData_Offset], pReplace_Data, pReplace_Count);
+    // Copy data which place after replacing part.
+    memcpy(&new_data[pBufferData_Offset + pReplace_Count], &mData.get()[pBufferData_Offset + pBufferData_Count], new_data_size - (pBufferData_Offset + pReplace_Count));
+    // Apply new data
+    mData.reset(new_data, std::default_delete<uint8_t[]>());
+    byteLength = new_data_size;
+
+    return true;
+}
+
+inline size_t Buffer::AppendData(uint8_t *data, size_t length) {
+    const size_t offset = this->byteLength;
+
+    // Force alignment to 4 bits
+    const size_t paddedLength = (length + 3) & ~3;
+    Grow(paddedLength);
+    memcpy(mData.get() + offset, data, length);
+    memset(mData.get() + offset + length, 0, paddedLength - length);
+    return offset;
+}
+
+inline void Buffer::Grow(size_t amount) {
+    if (amount <= 0) {
+        return;
+    }
+
+    // Capacity is big enough
+    if (capacity >= byteLength + amount) {
+        byteLength += amount;
+        return;
+    }
+
+    // Just allocate data which we need
+    capacity = byteLength + amount;
+
+    uint8_t *b = new uint8_t[capacity];
+    if (nullptr != mData) {
+        memcpy(b, mData.get(), byteLength);
+    }
+    mData.reset(b, std::default_delete<uint8_t[]>());
+    byteLength += amount;
+}
+
+//
+// struct BufferView
+//
+inline void BufferView::Read(Value &obj, Asset &r) {
+    if (Value *bufferVal = FindUInt(obj, "buffer")) {
+        buffer = r.buffers.Retrieve(bufferVal->GetUint());
+    }
+
+    if (!buffer) {
+        throw DeadlyImportError("GLTF: Buffer view without valid buffer.");
+    }
+
+    byteOffset = MemberOrDefault(obj, "byteOffset", size_t(0));
+    byteLength = MemberOrDefault(obj, "byteLength", size_t(0));
+    byteStride = MemberOrDefault(obj, "byteStride", 0u);
+
+    // Check length
+    if ((byteOffset + byteLength) > buffer->byteLength) {
+        throw DeadlyImportError("GLTF: Buffer view with offset/length (", byteOffset, "/", byteLength, ") is out of range.");
+    }
+}
+
+inline uint8_t *BufferView::GetPointer(size_t accOffset) {
+    if (!buffer) {
+        return nullptr;
+    }
+    uint8_t *basePtr = buffer->GetPointer();
+    if (!basePtr) {
+        return nullptr;
+    }
+
+    size_t offset = accOffset + byteOffset;
+    if (buffer->EncodedRegion_Current != nullptr) {
+        const size_t begin = buffer->EncodedRegion_Current->Offset;
+        const size_t end = begin + buffer->EncodedRegion_Current->DecodedData_Length;
+        if ((offset >= begin) && (offset < end)) {
+            return &buffer->EncodedRegion_Current->DecodedData[offset - begin];
+        }
+    }
+
+    return basePtr + offset;
+}
+
+//
+// struct Accessor
+//
+inline void Accessor::Sparse::PopulateData(size_t numBytes, uint8_t *bytes) {
+    if (bytes) {
+        data.assign(bytes, bytes + numBytes);
+    } else {
+        data.resize(numBytes, 0x00);
+    }
+}
+
+inline void Accessor::Sparse::PatchData(unsigned int elementSize) {
+    uint8_t *pIndices = indices->GetPointer(indicesByteOffset);
+    const unsigned int indexSize = int(ComponentTypeSize(indicesType));
+    uint8_t *indicesEnd = pIndices + count * indexSize;
+
+    uint8_t *pValues = values->GetPointer(valuesByteOffset);
+    while (pIndices != indicesEnd) {
+        size_t offset;
+        switch (indicesType) {
+        case ComponentType_UNSIGNED_BYTE:
+            offset = *pIndices;
+            break;
+        case ComponentType_UNSIGNED_SHORT:
+            offset = *reinterpret_cast<uint16_t *>(pIndices);
+            break;
+        case ComponentType_UNSIGNED_INT:
+            offset = *reinterpret_cast<uint32_t *>(pIndices);
+            break;
+        default:
+            // have fun with float and negative values from signed types as indices.
+            throw DeadlyImportError("Unsupported component type in index.");
+        }
+
+        offset *= elementSize;
+
+        if (offset + elementSize > data.size()) {
+            throw DeadlyImportError("Invalid sparse accessor. Byte offset for patching points outside allocated memory.");
+        }
+
+        std::memcpy(data.data() + offset, pValues, elementSize);
+
+        pValues += elementSize;
+        pIndices += indexSize;
+    }
+}
+
+inline void Accessor::Read(Value &obj, Asset &r) {
+    if (Value *bufferViewVal = FindUInt(obj, "bufferView")) {
+        bufferView = r.bufferViews.Retrieve(bufferViewVal->GetUint());
+    }
+
+    byteOffset = MemberOrDefault(obj, "byteOffset", size_t(0));
+    componentType = MemberOrDefault(obj, "componentType", ComponentType_BYTE);
+    {
+        const Value *countValue = FindUInt(obj, "count");
+        if (!countValue) {
+            throw DeadlyImportError("A count value is required, when reading ", id.c_str(), name.empty() ? "" : " (" + name + ")");
+        }
+        count = countValue->GetUint();
+    }
+
+    const char *typestr;
+    type = ReadMember(obj, "type", typestr) ? AttribType::FromString(typestr) : AttribType::SCALAR;
+
+    if (bufferView) {
+        // Check length
+        unsigned long long byteLength = (unsigned long long)GetBytesPerComponent() * (unsigned long long)count;
+
+        // handle integer overflow
+        if (byteLength < count) {
+            throw DeadlyImportError("GLTF: Accessor with offset/count (", byteOffset, "/", count, ") is out of range.");
+        }
+
+        if ((byteOffset + byteLength) > bufferView->byteLength || (bufferView->byteOffset + byteOffset + byteLength) > bufferView->buffer->byteLength) {
+            throw DeadlyImportError("GLTF: Accessor with offset/length (", byteOffset, "/", byteLength, ") is out of range.");
+        }
+    }
+
+    if (Value *sparseValue = FindObject(obj, "sparse")) {
+        sparse.reset(new Sparse);
+        // count
+        ReadMember(*sparseValue, "count", sparse->count);
+
+        // indices
+        if (Value *indicesValue = FindObject(*sparseValue, "indices")) {
+            //indices bufferView
+            Value *indiceViewID = FindUInt(*indicesValue, "bufferView");
+            sparse->indices = r.bufferViews.Retrieve(indiceViewID->GetUint());
+            //indices byteOffset
+            sparse->indicesByteOffset = MemberOrDefault(*indicesValue, "byteOffset", size_t(0));
+            //indices componentType
+            sparse->indicesType = MemberOrDefault(*indicesValue, "componentType", ComponentType_BYTE);
+            //sparse->indices->Read(*indicesValue, r);
+        } else {
+            // indicesType
+            sparse->indicesType = MemberOrDefault(*sparseValue, "componentType", ComponentType_UNSIGNED_SHORT);
+        }
+
+        // value
+        if (Value *valuesValue = FindObject(*sparseValue, "values")) {
+            //value bufferView
+            Value *valueViewID = FindUInt(*valuesValue, "bufferView");
+            sparse->values = r.bufferViews.Retrieve(valueViewID->GetUint());
+            //value byteOffset
+            sparse->valuesByteOffset = MemberOrDefault(*valuesValue, "byteOffset", size_t(0));
+            //sparse->values->Read(*valuesValue, r);
+        }
+
+
+        const unsigned int elementSize = GetElementSize();
+        const size_t dataSize = count * elementSize;
+        sparse->PopulateData(dataSize, bufferView ? bufferView->GetPointer(byteOffset) : 0);
+        sparse->PatchData(elementSize);
+    }
+}
+
+inline unsigned int Accessor::GetNumComponents() {
+    return AttribType::GetNumComponents(type);
+}
+
+inline unsigned int Accessor::GetBytesPerComponent() {
+    return int(ComponentTypeSize(componentType));
+}
+
+inline unsigned int Accessor::GetElementSize() {
+    return GetNumComponents() * GetBytesPerComponent();
+}
+
+inline uint8_t *Accessor::GetPointer() {
+    if (decodedBuffer)
+        return decodedBuffer->GetPointer();
+
+    if (sparse)
+        return sparse->data.data();
+
+    if (!bufferView || !bufferView->buffer) return nullptr;
+    uint8_t *basePtr = bufferView->buffer->GetPointer();
+    if (!basePtr) return nullptr;
+
+    size_t offset = byteOffset + bufferView->byteOffset;
+
+    // Check if region is encoded.
+    if (bufferView->buffer->EncodedRegion_Current != nullptr) {
+        const size_t begin = bufferView->buffer->EncodedRegion_Current->Offset;
+        const size_t end = begin + bufferView->buffer->EncodedRegion_Current->DecodedData_Length;
+
+        if ((offset >= begin) && (offset < end))
+            return &bufferView->buffer->EncodedRegion_Current->DecodedData[offset - begin];
+    }
+
+    return basePtr + offset;
+}
+
+inline size_t Accessor::GetStride() {
+    // Decoded buffer is always packed
+    if (decodedBuffer)
+        return GetElementSize();
+
+    // Sparse and normal bufferView
+    return (bufferView && bufferView->byteStride ? bufferView->byteStride : GetElementSize());
+}
+
+inline size_t Accessor::GetMaxByteSize() {
+    if (decodedBuffer)
+        return decodedBuffer->byteLength;
+
+    return (bufferView ? bufferView->byteLength : sparse->data.size());
+}
+
+template <class T>
+void Accessor::ExtractData(T *&outData) {
+    uint8_t *data = GetPointer();
+    if (!data) {
+        throw DeadlyImportError("GLTF2: data is null when extracting data from ", getContextForErrorMessages(id, name));
+    }
+
+    const size_t elemSize = GetElementSize();
+    const size_t totalSize = elemSize * count;
+
+    const size_t stride = GetStride();
+
+    const size_t targetElemSize = sizeof(T);
+
+    if (elemSize > targetElemSize) {
+        throw DeadlyImportError("GLTF: elemSize ", elemSize, " > targetElemSize ", targetElemSize, " in ", getContextForErrorMessages(id, name));
+    }
+
+    const size_t maxSize = GetMaxByteSize();
+    if (count * stride > maxSize) {
+        throw DeadlyImportError("GLTF: count*stride ", (count * stride), " > maxSize ", maxSize, " in ", getContextForErrorMessages(id, name));
+    }
+
+    outData = new T[count];
+    if (stride == elemSize && targetElemSize == elemSize) {
+        memcpy(outData, data, totalSize);
+    } else {
+        for (size_t i = 0; i < count; ++i) {
+            memcpy(outData + i, data + i * stride, elemSize);
+        }
+    }
+}
+
+inline void Accessor::WriteData(size_t _count, const void *src_buffer, size_t src_stride) {
+    uint8_t *buffer_ptr = bufferView->buffer->GetPointer();
+    size_t offset = byteOffset + bufferView->byteOffset;
+
+    size_t dst_stride = GetNumComponents() * GetBytesPerComponent();
+
+    const uint8_t *src = reinterpret_cast<const uint8_t *>(src_buffer);
+    uint8_t *dst = reinterpret_cast<uint8_t *>(buffer_ptr + offset);
+
+    ai_assert(dst + _count * dst_stride <= buffer_ptr + bufferView->buffer->byteLength);
+    CopyData(_count, src, src_stride, dst, dst_stride);
+}
+
+inline void Accessor::WriteSparseValues(size_t _count, const void *src_data, size_t src_dataStride) {
+    if (!sparse)
+        return;
+
+    // values
+    uint8_t *value_buffer_ptr = sparse->values->buffer->GetPointer();
+    size_t value_offset = sparse->valuesByteOffset + sparse->values->byteOffset;
+    size_t value_dst_stride = GetNumComponents() * GetBytesPerComponent();
+    const uint8_t *value_src = reinterpret_cast<const uint8_t *>(src_data);
+    uint8_t *value_dst = reinterpret_cast<uint8_t *>(value_buffer_ptr + value_offset);
+    ai_assert(value_dst + _count * value_dst_stride <= value_buffer_ptr + sparse->values->buffer->byteLength);
+    CopyData(_count, value_src, src_dataStride, value_dst, value_dst_stride);
+}
+
+inline void Accessor::WriteSparseIndices(size_t _count, const void *src_idx, size_t src_idxStride) {
+    if (!sparse)
+        return;
+
+    // indices
+    uint8_t *indices_buffer_ptr = sparse->indices->buffer->GetPointer();
+    size_t indices_offset = sparse->indicesByteOffset + sparse->indices->byteOffset;
+    size_t indices_dst_stride = 1 * sizeof(unsigned short);
+    const uint8_t *indices_src = reinterpret_cast<const uint8_t *>(src_idx);
+    uint8_t *indices_dst = reinterpret_cast<uint8_t *>(indices_buffer_ptr + indices_offset);
+    ai_assert(indices_dst + _count * indices_dst_stride <= indices_buffer_ptr + sparse->indices->buffer->byteLength);
+    CopyData(_count, indices_src, src_idxStride, indices_dst, indices_dst_stride);
+}
+
+inline Accessor::Indexer::Indexer(Accessor &acc) :
+    accessor(acc),
+    data(acc.GetPointer()),
+    elemSize(acc.GetElementSize()),
+    stride(acc.GetStride()) {
+}
+
+//! Accesses the i-th value as defined by the accessor
+template <class T>
+T Accessor::Indexer::GetValue(int i) {
+    ai_assert(data);
+    if (i * stride >= accessor.GetMaxByteSize()) {
+        throw DeadlyImportError("GLTF: Invalid index ", i, ", count out of range for buffer with stride ", stride, " and size ", accessor.GetMaxByteSize(), ".");
+    }
+    // Ensure that the memcpy doesn't overwrite the local.
+    const size_t sizeToCopy = std::min(elemSize, sizeof(T));
+    T value = T();
+    // Assume platform endianness matches GLTF binary data (which is little-endian).
+    memcpy(&value, data + i * stride, sizeToCopy);
+    return value;
+}
+
+inline Image::Image() :
+        width(0),
+        height(0),
+        mDataLength(0) {
+}
+
+inline void Image::Read(Value &obj, Asset &r) {
+    //basisu: no need to handle .ktx2, .basis, load as is
+    if (!mDataLength) {
+        Value *curUri = FindString(obj, "uri");
+        if (nullptr != curUri) {
+            const char *uristr = curUri->GetString();
+
+            glTFCommon::Util::DataURI dataURI;
+            if (ParseDataURI(uristr, curUri->GetStringLength(), dataURI)) {
+                mimeType = dataURI.mediaType;
+                if (dataURI.base64) {
+                    uint8_t *ptr = nullptr;
+                    mDataLength = Base64::Decode(dataURI.data, dataURI.dataLength, ptr);
+                    mData.reset(ptr);
+                }
+            } else {
+                this->uri = uristr;
+            }
+        } else if (Value *bufferViewVal = FindUInt(obj, "bufferView")) {
+            this->bufferView = r.bufferViews.Retrieve(bufferViewVal->GetUint());
+            if (Value *mtype = FindString(obj, "mimeType")) {
+                this->mimeType = mtype->GetString();
+            }
+            if (!this->bufferView || this->mimeType.empty()) {
+                throw DeadlyImportError("GLTF2: ", getContextForErrorMessages(id, name), " does not have a URI, so it must have a valid bufferView and mimetype");
+            }
+
+            Ref<Buffer> buffer = this->bufferView->buffer;
+
+            this->mDataLength = this->bufferView->byteLength;
+            // maybe this memcpy could be avoided if aiTexture does not delete[] pcData at destruction.
+
+            this->mData.reset(new uint8_t[this->mDataLength]);
+            memcpy(this->mData.get(), buffer->GetPointer() + this->bufferView->byteOffset, this->mDataLength);
+        } else {
+            throw DeadlyImportError("GLTF2: ", getContextForErrorMessages(id, name), " should have either a URI of a bufferView and mimetype");
+        }
+    }
+}
+
+inline uint8_t *Image::StealData() {
+    mDataLength = 0;
+    return mData.release();
+}
+
+// Never take over the ownership of data whenever binary or not
+inline void Image::SetData(uint8_t *data, size_t length, Asset &r) {
+    Ref<Buffer> b = r.GetBodyBuffer();
+    if (b) { // binary file: append to body
+        std::string bvId = r.FindUniqueID(this->id, "imgdata");
+        bufferView = r.bufferViews.Create(bvId);
+
+        bufferView->buffer = b;
+        bufferView->byteLength = length;
+        bufferView->byteOffset = b->AppendData(data, length);
+    } else { // text file: will be stored as a data uri
+        uint8_t *temp = new uint8_t[length];
+        memcpy(temp, data, length);
+        this->mData.reset(temp);
+        this->mDataLength = length;
+    }
+}
+
+inline void Sampler::Read(Value &obj, Asset & /*r*/) {
+    SetDefaults();
+
+    ReadMember(obj, "name", name);
+    ReadMember(obj, "magFilter", magFilter);
+    ReadMember(obj, "minFilter", minFilter);
+    ReadMember(obj, "wrapS", wrapS);
+    ReadMember(obj, "wrapT", wrapT);
+}
+
+inline void Sampler::SetDefaults() {
+    //only wrapping modes have defaults
+    wrapS = SamplerWrap::Repeat;
+    wrapT = SamplerWrap::Repeat;
+    magFilter = SamplerMagFilter::UNSET;
+    minFilter = SamplerMinFilter::UNSET;
+}
+
+inline void Texture::Read(Value &obj, Asset &r) {
+    if (Value *sourceVal = FindUInt(obj, "source")) {
+        source = r.images.Retrieve(sourceVal->GetUint());
+    }
+
+    if (Value *samplerVal = FindUInt(obj, "sampler")) {
+        sampler = r.samplers.Retrieve(samplerVal->GetUint());
+    }
+}
+
+void Material::SetTextureProperties(Asset &r, Value *prop, TextureInfo &out) {
+    if (r.extensionsUsed.KHR_texture_transform) {
+        if (Value *pKHR_texture_transform = FindExtension(*prop, "KHR_texture_transform")) {
+            out.textureTransformSupported = true;
+            if (Value *array = FindArray(*pKHR_texture_transform, "offset")) {
+                out.TextureTransformExt_t.offset[0] = (*array)[0].GetFloat();
+                out.TextureTransformExt_t.offset[1] = (*array)[1].GetFloat();
+            } else {
+                out.TextureTransformExt_t.offset[0] = 0;
+                out.TextureTransformExt_t.offset[1] = 0;
+            }
+
+            if (!ReadMember(*pKHR_texture_transform, "rotation", out.TextureTransformExt_t.rotation)) {
+                out.TextureTransformExt_t.rotation = 0;
+            }
+
+            if (Value *array = FindArray(*pKHR_texture_transform, "scale")) {
+                out.TextureTransformExt_t.scale[0] = (*array)[0].GetFloat();
+                out.TextureTransformExt_t.scale[1] = (*array)[1].GetFloat();
+            } else {
+                out.TextureTransformExt_t.scale[0] = 1;
+                out.TextureTransformExt_t.scale[1] = 1;
+            }
+        }
+    }
+
+    if (Value *indexProp = FindUInt(*prop, "index")) {
+        out.texture = r.textures.Retrieve(indexProp->GetUint());
+    }
+
+    if (Value *texcoord = FindUInt(*prop, "texCoord")) {
+        out.texCoord = texcoord->GetUint();
+    }
+}
+
+inline void Material::ReadTextureProperty(Asset &r, Value &vals, const char *propName, TextureInfo &out) {
+    if (Value *prop = FindMember(vals, propName)) {
+        SetTextureProperties(r, prop, out);
+    }
+}
+
+inline void Material::ReadTextureProperty(Asset &r, Value &vals, const char *propName, NormalTextureInfo &out) {
+    if (Value *prop = FindMember(vals, propName)) {
+        SetTextureProperties(r, prop, out);
+
+        if (Value *scale = FindNumber(*prop, "scale")) {
+            out.scale = static_cast<float>(scale->GetDouble());
+        }
+    }
+}
+
+inline void Material::ReadTextureProperty(Asset &r, Value &vals, const char *propName, OcclusionTextureInfo &out) {
+    if (Value *prop = FindMember(vals, propName)) {
+        SetTextureProperties(r, prop, out);
+
+        if (Value *strength = FindNumber(*prop, "strength")) {
+            out.strength = static_cast<float>(strength->GetDouble());
+        }
+    }
+}
+
+inline void Material::Read(Value &material, Asset &r) {
+    SetDefaults();
+
+    if (Value *curPbrMetallicRoughness = FindObject(material, "pbrMetallicRoughness")) {
+        ReadMember(*curPbrMetallicRoughness, "baseColorFactor", this->pbrMetallicRoughness.baseColorFactor);
+        ReadTextureProperty(r, *curPbrMetallicRoughness, "baseColorTexture", this->pbrMetallicRoughness.baseColorTexture);
+        ReadTextureProperty(r, *curPbrMetallicRoughness, "metallicRoughnessTexture", this->pbrMetallicRoughness.metallicRoughnessTexture);
+        ReadMember(*curPbrMetallicRoughness, "metallicFactor", this->pbrMetallicRoughness.metallicFactor);
+        ReadMember(*curPbrMetallicRoughness, "roughnessFactor", this->pbrMetallicRoughness.roughnessFactor);
+    }
+
+    ReadTextureProperty(r, material, "normalTexture", this->normalTexture);
+    ReadTextureProperty(r, material, "occlusionTexture", this->occlusionTexture);
+    ReadTextureProperty(r, material, "emissiveTexture", this->emissiveTexture);
+    ReadMember(material, "emissiveFactor", this->emissiveFactor);
+
+    ReadMember(material, "doubleSided", this->doubleSided);
+    ReadMember(material, "alphaMode", this->alphaMode);
+    ReadMember(material, "alphaCutoff", this->alphaCutoff);
+
+    if (Value *extensions = FindObject(material, "extensions")) {
+        if (r.extensionsUsed.KHR_materials_pbrSpecularGlossiness) {
+            if (Value *curPbrSpecularGlossiness = FindObject(*extensions, "KHR_materials_pbrSpecularGlossiness")) {
+                PbrSpecularGlossiness pbrSG;
+
+                ReadMember(*curPbrSpecularGlossiness, "diffuseFactor", pbrSG.diffuseFactor);
+                ReadTextureProperty(r, *curPbrSpecularGlossiness, "diffuseTexture", pbrSG.diffuseTexture);
+                ReadTextureProperty(r, *curPbrSpecularGlossiness, "specularGlossinessTexture", pbrSG.specularGlossinessTexture);
+                ReadMember(*curPbrSpecularGlossiness, "specularFactor", pbrSG.specularFactor);
+                ReadMember(*curPbrSpecularGlossiness, "glossinessFactor", pbrSG.glossinessFactor);
+
+                this->pbrSpecularGlossiness = Nullable<PbrSpecularGlossiness>(pbrSG);
+            }
+        }
+
+        // Extension KHR_texture_transform is handled in ReadTextureProperty
+
+        if (r.extensionsUsed.KHR_materials_sheen) {
+            if (Value *curMaterialSheen = FindObject(*extensions, "KHR_materials_sheen")) {
+                MaterialSheen sheen;
+
+                ReadMember(*curMaterialSheen, "sheenColorFactor", sheen.sheenColorFactor);
+                ReadTextureProperty(r, *curMaterialSheen, "sheenColorTexture", sheen.sheenColorTexture);
+                ReadMember(*curMaterialSheen, "sheenRoughnessFactor", sheen.sheenRoughnessFactor);
+                ReadTextureProperty(r, *curMaterialSheen, "sheenRoughnessTexture", sheen.sheenRoughnessTexture);
+
+                this->materialSheen = Nullable<MaterialSheen>(sheen);
+            }
+        }
+
+        if (r.extensionsUsed.KHR_materials_clearcoat) {
+            if (Value *curMaterialClearcoat = FindObject(*extensions, "KHR_materials_clearcoat")) {
+                MaterialClearcoat clearcoat;
+
+                ReadMember(*curMaterialClearcoat, "clearcoatFactor", clearcoat.clearcoatFactor);
+                ReadTextureProperty(r, *curMaterialClearcoat, "clearcoatTexture", clearcoat.clearcoatTexture);
+                ReadMember(*curMaterialClearcoat, "clearcoatRoughnessFactor", clearcoat.clearcoatRoughnessFactor);
+                ReadTextureProperty(r, *curMaterialClearcoat, "clearcoatRoughnessTexture", clearcoat.clearcoatRoughnessTexture);
+                ReadTextureProperty(r, *curMaterialClearcoat, "clearcoatNormalTexture", clearcoat.clearcoatNormalTexture);
+
+                this->materialClearcoat = Nullable<MaterialClearcoat>(clearcoat);
+            }
+        }
+
+        if (r.extensionsUsed.KHR_materials_transmission) {
+            if (Value *curMaterialTransmission = FindObject(*extensions, "KHR_materials_transmission")) {
+                MaterialTransmission transmission;
+
+                ReadMember(*curMaterialTransmission, "transmissionFactor", transmission.transmissionFactor);
+                ReadTextureProperty(r, *curMaterialTransmission, "transmissionTexture", transmission.transmissionTexture);
+
+                this->materialTransmission = Nullable<MaterialTransmission>(transmission);
+            }
+        }
+
+        if (r.extensionsUsed.KHR_materials_volume) {
+            if (Value *curMaterialVolume = FindObject(*extensions, "KHR_materials_volume")) {
+                MaterialVolume volume;
+
+                ReadMember(*curMaterialVolume, "thicknessFactor", volume.thicknessFactor);
+                ReadTextureProperty(r, *curMaterialVolume, "thicknessTexture", volume.thicknessTexture);
+                ReadMember(*curMaterialVolume, "attenuationDistance", volume.attenuationDistance);
+                ReadMember(*curMaterialVolume, "attenuationColor", volume.attenuationColor);
+
+                this->materialVolume = Nullable<MaterialVolume>(volume);
+            }
+        }
+
+        if (r.extensionsUsed.KHR_materials_ior) {
+            if (Value *curMaterialIOR = FindObject(*extensions, "KHR_materials_ior")) {
+                MaterialIOR ior;
+
+                ReadMember(*curMaterialIOR, "ior", ior.ior);
+
+                this->materialIOR = Nullable<MaterialIOR>(ior);
+            }
+        }
+
+        unlit = nullptr != FindObject(*extensions, "KHR_materials_unlit");
+    }
+}
+
+inline void Material::SetDefaults() {
+    //pbr materials
+    SetVector(pbrMetallicRoughness.baseColorFactor, defaultBaseColor);
+    pbrMetallicRoughness.metallicFactor = 1.0f;
+    pbrMetallicRoughness.roughnessFactor = 1.0f;
+
+    SetVector(emissiveFactor, defaultEmissiveFactor);
+    alphaMode = "OPAQUE";
+    alphaCutoff = 0.5f;
+    doubleSided = false;
+    unlit = false;
+}
+
+inline void PbrSpecularGlossiness::SetDefaults() {
+    //pbrSpecularGlossiness properties
+    SetVector(diffuseFactor, defaultDiffuseFactor);
+    SetVector(specularFactor, defaultSpecularFactor);
+    glossinessFactor = 1.0f;
+}
+
+inline void MaterialSheen::SetDefaults() {
+    //KHR_materials_sheen properties
+    SetVector(sheenColorFactor, defaultSheenFactor);
+    sheenRoughnessFactor = 0.f;
+}
+
+inline void MaterialVolume::SetDefaults() {
+    //KHR_materials_volume properties
+    thicknessFactor = 0.f;
+    attenuationDistance = INFINITY;
+    SetVector(attenuationColor, defaultAttenuationColor);
+}
+
+inline void MaterialIOR::SetDefaults() {
+    //KHR_materials_ior properties
+    ior = 1.5f;
+}
+
+inline void Mesh::Read(Value &pJSON_Object, Asset &pAsset_Root) {
+    Value *curName = FindMember(pJSON_Object, "name");
+    if (nullptr != curName && curName->IsString()) {
+        name = curName->GetString();
+    }
+
+    /****************** Mesh primitives ******************/
+    Value *curPrimitives = FindArray(pJSON_Object, "primitives");
+    if (nullptr != curPrimitives) {
+        this->primitives.resize(curPrimitives->Size());
+        for (unsigned int i = 0; i < curPrimitives->Size(); ++i) {
+            Value &primitive = (*curPrimitives)[i];
+
+            Primitive &prim = this->primitives[i];
+            prim.mode = MemberOrDefault(primitive, "mode", PrimitiveMode_TRIANGLES);
+
+            if (Value *indices = FindUInt(primitive, "indices")) {
+                prim.indices = pAsset_Root.accessors.Retrieve(indices->GetUint());
+            }
+
+            if (Value *material = FindUInt(primitive, "material")) {
+                prim.material = pAsset_Root.materials.Retrieve(material->GetUint());
+            }
+
+            if (Value *attrs = FindObject(primitive, "attributes")) {
+                for (Value::MemberIterator it = attrs->MemberBegin(); it != attrs->MemberEnd(); ++it) {
+                    if (!it->value.IsUint()) continue;
+                    const char *attr = it->name.GetString();
+                    // Valid attribute semantics include POSITION, NORMAL, TANGENT, TEXCOORD, COLOR, JOINT, JOINTMATRIX,
+                    // and WEIGHT.Attribute semantics can be of the form[semantic]_[set_index], e.g., TEXCOORD_0, TEXCOORD_1, etc.
+
+                    int undPos = 0;
+                    Mesh::AccessorList *vec = nullptr;
+                    if (GetAttribVector(prim, attr, vec, undPos)) {
+                        size_t idx = (attr[undPos] == '_') ? atoi(attr + undPos + 1) : 0;
+                        if ((*vec).size() != idx) {
+                            throw DeadlyImportError("GLTF: Invalid attribute in mesh: ", name, " primitive: ", i, "attrib: ", attr,
+                                    ". All indices for indexed attribute semantics must start with 0 and be continuous positive integers: TEXCOORD_0, TEXCOORD_1, etc.");
+                        }
+                        (*vec).resize(idx + 1);
+                        (*vec)[idx] = pAsset_Root.accessors.Retrieve(it->value.GetUint());
+                    }
+                }
+            }
+
+#ifdef ASSIMP_ENABLE_DRACO
+            // KHR_draco_mesh_compression spec: Draco can only be used for glTF Triangles or Triangle Strips
+            if (pAsset_Root.extensionsUsed.KHR_draco_mesh_compression && (prim.mode == PrimitiveMode_TRIANGLES || prim.mode == PrimitiveMode_TRIANGLE_STRIP)) {
+                // Look for draco mesh compression extension and bufferView
+                // Skip if any missing
+                if (Value *dracoExt = FindExtension(primitive, "KHR_draco_mesh_compression")) {
+                    if (Value *bufView = FindUInt(*dracoExt, "bufferView")) {
+                        // Attempt to load indices and attributes using draco compression
+                        auto bufferView = pAsset_Root.bufferViews.Retrieve(bufView->GetUint());
+                        // Attempt to perform the draco decode on the buffer data
+                        const char *bufferViewData = reinterpret_cast<const char *>(bufferView->buffer->GetPointer() + bufferView->byteOffset);
+                        draco::DecoderBuffer decoderBuffer;
+                        decoderBuffer.Init(bufferViewData, bufferView->byteLength);
+                        draco::Decoder decoder;
+                        auto decodeResult = decoder.DecodeMeshFromBuffer(&decoderBuffer);
+                        if (!decodeResult.ok()) {
+                            // A corrupt Draco isn't actually fatal if the primitive data is also provided in a standard buffer, but does anyone do that?
+                            throw DeadlyImportError("GLTF: Invalid Draco mesh compression in mesh: ", name, " primitive: ", i, ": ", decodeResult.status().error_msg_string());
+                        }
+
+                        // Now we have a draco mesh
+                        const std::unique_ptr<draco::Mesh> &pDracoMesh = decodeResult.value();
+
+                        // Redirect the accessors to the decoded data
+
+                        // Indices
+                        SetDecodedIndexBuffer_Draco(*pDracoMesh, prim);
+
+                        // Vertex attributes
+                        if (Value *attrs = FindObject(*dracoExt, "attributes")) {
+                            for (Value::MemberIterator it = attrs->MemberBegin(); it != attrs->MemberEnd(); ++it) {
+                                if (!it->value.IsUint()) continue;
+                                const char *attr = it->name.GetString();
+
+                                int undPos = 0;
+                                Mesh::AccessorList *vec = nullptr;
+                                if (GetAttribVector(prim, attr, vec, undPos)) {
+                                    size_t idx = (attr[undPos] == '_') ? atoi(attr + undPos + 1) : 0;
+                                    if (idx >= (*vec).size()) {
+                                        throw DeadlyImportError("GLTF: Invalid draco attribute in mesh: ", name, " primitive: ", i, " attrib: ", attr,
+                                                ". All indices for indexed attribute semantics must start with 0 and be continuous positive integers: TEXCOORD_0, TEXCOORD_1, etc.");
+                                    }
+
+                                    if (!(*vec)[idx]) {
+                                        throw DeadlyImportError("GLTF: Invalid draco attribute in mesh: ", name, " primitive: ", i, " attrib: ", attr,
+                                                ". All draco-encoded attributes must also define an accessor.");
+                                    }
+
+                                    Accessor &attribAccessor = *(*vec)[idx];
+                                    if (attribAccessor.count == 0)
+                                        throw DeadlyImportError("GLTF: Invalid draco attribute in mesh: ", name, " primitive: ", i, " attrib: ", attr);
+
+                                    // Redirect this accessor to the appropriate Draco vertex attribute data
+                                    const uint32_t dracoAttribId = it->value.GetUint();
+                                    SetDecodedAttributeBuffer_Draco(*pDracoMesh, dracoAttribId, attribAccessor);
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+#endif
+
+            Value *targetsArray = FindArray(primitive, "targets");
+            if (nullptr != targetsArray) {
+                prim.targets.resize(targetsArray->Size());
+                for (unsigned int j = 0; j < targetsArray->Size(); ++j) {
+                    Value &target = (*targetsArray)[j];
+                    if (!target.IsObject()) {
+                        continue;
+                    }
+                    for (Value::MemberIterator it = target.MemberBegin(); it != target.MemberEnd(); ++it) {
+                        if (!it->value.IsUint()) {
+                            continue;
+                        }
+                        const char *attr = it->name.GetString();
+                        // Valid attribute semantics include POSITION, NORMAL, TANGENT
+                        int undPos = 0;
+                        Mesh::AccessorList *vec = nullptr;
+                        if (GetAttribTargetVector(prim, j, attr, vec, undPos)) {
+                            size_t idx = (attr[undPos] == '_') ? atoi(attr + undPos + 1) : 0;
+                            if ((*vec).size() <= idx) {
+                                (*vec).resize(idx + 1);
+                            }
+                            (*vec)[idx] = pAsset_Root.accessors.Retrieve(it->value.GetUint());
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    Value *curWeights = FindArray(pJSON_Object, "weights");
+    if (nullptr != curWeights) {
+        this->weights.resize(curWeights->Size());
+        for (unsigned int i = 0; i < curWeights->Size(); ++i) {
+            Value &weightValue = (*curWeights)[i];
+            if (weightValue.IsNumber()) {
+                this->weights[i] = weightValue.GetFloat();
+            }
+        }
+    }
+
+    Value *curExtras = FindObject(pJSON_Object, "extras");
+    if (nullptr != curExtras) {
+        if (Value *curTargetNames = FindArray(*curExtras, "targetNames")) {
+            this->targetNames.resize(curTargetNames->Size());
+            for (unsigned int i = 0; i < curTargetNames->Size(); ++i) {
+                Value &targetNameValue = (*curTargetNames)[i];
+                if (targetNameValue.IsString()) {
+                    this->targetNames[i] = targetNameValue.GetString();
+                }
+            }
+        }
+    }
+}
+
+inline void Camera::Read(Value &obj, Asset & /*r*/) {
+    std::string type_string = std::string(MemberOrDefault(obj, "type", "perspective"));
+    if (type_string == "orthographic") {
+        type = Camera::Orthographic;
+    } else {
+        type = Camera::Perspective;
+    }
+
+    const char *subobjId = (type == Camera::Orthographic) ? "orthographic" : "perspective";
+
+    Value *it = FindObject(obj, subobjId);
+    if (!it) throw DeadlyImportError("GLTF: Camera missing its parameters");
+
+    if (type == Camera::Perspective) {
+        cameraProperties.perspective.aspectRatio = MemberOrDefault(*it, "aspectRatio", 0.f);
+        cameraProperties.perspective.yfov = MemberOrDefault(*it, "yfov", 3.1415f / 2.f);
+        cameraProperties.perspective.zfar = MemberOrDefault(*it, "zfar", 100.f);
+        cameraProperties.perspective.znear = MemberOrDefault(*it, "znear", 0.01f);
+    } else {
+        cameraProperties.ortographic.xmag = MemberOrDefault(*it, "xmag", 1.f);
+        cameraProperties.ortographic.ymag = MemberOrDefault(*it, "ymag", 1.f);
+        cameraProperties.ortographic.zfar = MemberOrDefault(*it, "zfar", 100.f);
+        cameraProperties.ortographic.znear = MemberOrDefault(*it, "znear", 0.01f);
+    }
+}
+
+inline void Light::Read(Value &obj, Asset & /*r*/) {
+#ifndef M_PI
+    const float M_PI = 3.14159265358979323846f;
+#endif
+
+    std::string type_string;
+    ReadMember(obj, "type", type_string);
+    if (type_string == "directional")
+        type = Light::Directional;
+    else if (type_string == "point")
+        type = Light::Point;
+    else
+        type = Light::Spot;
+
+    name = MemberOrDefault(obj, "name", "");
+
+    SetVector(color, vec3{ 1.0f, 1.0f, 1.0f });
+    ReadMember(obj, "color", color);
+
+    intensity = MemberOrDefault(obj, "intensity", 1.0f);
+
+    ReadMember(obj, "range", range);
+
+    if (type == Light::Spot) {
+        Value *spot = FindObject(obj, "spot");
+        if (!spot) throw DeadlyImportError("GLTF: Light missing its spot parameters");
+        innerConeAngle = MemberOrDefault(*spot, "innerConeAngle", 0.0f);
+        outerConeAngle = MemberOrDefault(*spot, "outerConeAngle", static_cast<float>(M_PI / 4.0f));
+    }
+}
+
+inline void Node::Read(Value &obj, Asset &r) {
+    if (name.empty()) {
+        name = id;
+    }
+
+    Value *curChildren = FindArray(obj, "children");
+    if (nullptr != curChildren) {
+        this->children.reserve(curChildren->Size());
+        for (unsigned int i = 0; i < curChildren->Size(); ++i) {
+            Value &child = (*curChildren)[i];
+            if (child.IsUint()) {
+                // get/create the child node
+                Ref<Node> chn = r.nodes.Retrieve(child.GetUint());
+                if (chn) {
+                    this->children.push_back(chn);
+                }
+            }
+        }
+    }
+
+    Value *curMatrix = FindArray(obj, "matrix");
+    if (nullptr != curMatrix) {
+        ReadValue(*curMatrix, this->matrix);
+    } else {
+        ReadMember(obj, "translation", translation);
+        ReadMember(obj, "scale", scale);
+        ReadMember(obj, "rotation", rotation);
+    }
+
+    Value *curMesh = FindUInt(obj, "mesh");
+    if (nullptr != curMesh) {
+        unsigned int numMeshes = 1;
+        this->meshes.reserve(numMeshes);
+        Ref<Mesh> meshRef = r.meshes.Retrieve((*curMesh).GetUint());
+        if (meshRef) {
+            this->meshes.push_back(meshRef);
+        }
+    }
+
+    // Do not retrieve a skin here, just take a reference, to avoid infinite recursion
+    // Skins will be properly loaded later
+    Value *curSkin = FindUInt(obj, "skin");
+    if (nullptr != curSkin) {
+        this->skin = r.skins.Get(curSkin->GetUint());
+    }
+
+    Value *curCamera = FindUInt(obj, "camera");
+    if (nullptr != curCamera) {
+        this->camera = r.cameras.Retrieve(curCamera->GetUint());
+        if (this->camera) {
+            this->camera->id = this->id;
+        }
+    }
+
+    Value *curExtensions = FindObject(obj, "extensions");
+    if (nullptr != curExtensions) {
+        if (r.extensionsUsed.KHR_lights_punctual) {
+            if (Value *ext = FindObject(*curExtensions, "KHR_lights_punctual")) {
+                Value *curLight = FindUInt(*ext, "light");
+                if (nullptr != curLight) {
+                    this->light = r.lights.Retrieve(curLight->GetUint());
+                    if (this->light) {
+                        this->light->id = this->id;
+                    }
+                }
+            }
+        }
+    }
+}
+
+inline void Scene::Read(Value &obj, Asset &r) {
+    if (Value *scene_name = FindString(obj, "name")) {
+        if (scene_name->IsString()) {
+            this->name = scene_name->GetString();
+        }
+    }
+    if (Value *array = FindArray(obj, "nodes")) {
+        for (unsigned int i = 0; i < array->Size(); ++i) {
+            if (!(*array)[i].IsUint()) continue;
+            Ref<Node> node = r.nodes.Retrieve((*array)[i].GetUint());
+            if (node)
+                this->nodes.push_back(node);
+        }
+    }
+}
+
+inline void Skin::Read(Value &obj, Asset &r) {
+    if (Value *matrices = FindUInt(obj, "inverseBindMatrices")) {
+        inverseBindMatrices = r.accessors.Retrieve(matrices->GetUint());
+    }
+
+    if (Value *joints = FindArray(obj, "joints")) {
+        for (unsigned i = 0; i < joints->Size(); ++i) {
+            if (!(*joints)[i].IsUint()) continue;
+            Ref<Node> node = r.nodes.Retrieve((*joints)[i].GetUint());
+            if (node) {
+                this->jointNames.push_back(node);
+            }
+        }
+    }
+}
+
+inline void Animation::Read(Value &obj, Asset &r) {
+    Value *curSamplers = FindArray(obj, "samplers");
+    if (nullptr != curSamplers) {
+        for (unsigned i = 0; i < curSamplers->Size(); ++i) {
+            Value &sampler = (*curSamplers)[i];
+
+            Sampler s;
+            if (Value *input = FindUInt(sampler, "input")) {
+                s.input = r.accessors.Retrieve(input->GetUint());
+            }
+            if (Value *output = FindUInt(sampler, "output")) {
+                s.output = r.accessors.Retrieve(output->GetUint());
+            }
+            s.interpolation = Interpolation_LINEAR;
+            if (Value *interpolation = FindString(sampler, "interpolation")) {
+                const std::string interp = interpolation->GetString();
+                if (interp == "LINEAR") {
+                    s.interpolation = Interpolation_LINEAR;
+                } else if (interp == "STEP") {
+                    s.interpolation = Interpolation_STEP;
+                } else if (interp == "CUBICSPLINE") {
+                    s.interpolation = Interpolation_CUBICSPLINE;
+                }
+            }
+            this->samplers.push_back(s);
+        }
+    }
+
+    Value *curChannels = FindArray(obj, "channels");
+    if (nullptr != curChannels) {
+        for (unsigned i = 0; i < curChannels->Size(); ++i) {
+            Value &channel = (*curChannels)[i];
+
+            Channel c;
+            Value *curSampler = FindUInt(channel, "sampler");
+            if (nullptr != curSampler) {
+                c.sampler = curSampler->GetUint();
+            }
+
+            if (Value *target = FindObject(channel, "target")) {
+                if (Value *node = FindUInt(*target, "node")) {
+                    c.target.node = r.nodes.Retrieve(node->GetUint());
+                }
+                if (Value *path = FindString(*target, "path")) {
+                    const std::string p = path->GetString();
+                    if (p == "translation") {
+                        c.target.path = AnimationPath_TRANSLATION;
+                    } else if (p == "rotation") {
+                        c.target.path = AnimationPath_ROTATION;
+                    } else if (p == "scale") {
+                        c.target.path = AnimationPath_SCALE;
+                    } else if (p == "weights") {
+                        c.target.path = AnimationPath_WEIGHTS;
+                    }
+                }
+            }
+            this->channels.push_back(c);
+        }
+    }
+}
+
+inline void AssetMetadata::Read(Document &doc) {
+    if (Value *obj = FindObject(doc, "asset")) {
+        ReadMember(*obj, "copyright", copyright);
+        ReadMember(*obj, "generator", generator);
+
+        if (Value *versionString = FindStringInContext(*obj, "version", "\"asset\"")) {
+            version = versionString->GetString();
+        }
+        Value *curProfile = FindObjectInContext(*obj, "profile", "\"asset\"");
+        if (nullptr != curProfile) {
+            ReadMember(*curProfile, "api", this->profile.api);
+            ReadMember(*curProfile, "version", this->profile.version);
+        }
+    }
+
+    if (version.empty() || version[0] != '2') {
+        throw DeadlyImportError("GLTF: Unsupported glTF version: ", version);
+    }
+}
+
+//
+// Asset methods implementation
+//
+
+inline void Asset::ReadBinaryHeader(IOStream &stream, std::vector<char> &sceneData) {
+    ASSIMP_LOG_DEBUG("Reading GLTF2 binary");
+    GLB_Header header;
+    if (stream.Read(&header, sizeof(header), 1) != 1) {
+        throw DeadlyImportError("GLTF: Unable to read the file header");
+    }
+
+    if (strncmp((char *)header.magic, AI_GLB_MAGIC_NUMBER, sizeof(header.magic)) != 0) {
+        throw DeadlyImportError("GLTF: Invalid binary glTF file");
+    }
+
+    AI_SWAP4(header.version);
+    asset.version = ai_to_string(header.version);
+    if (header.version != 2) {
+        throw DeadlyImportError("GLTF: Unsupported binary glTF version");
+    }
+
+    GLB_Chunk chunk;
+    if (stream.Read(&chunk, sizeof(chunk), 1) != 1) {
+        throw DeadlyImportError("GLTF: Unable to read JSON chunk");
+    }
+
+    AI_SWAP4(chunk.chunkLength);
+    AI_SWAP4(chunk.chunkType);
+
+    if (chunk.chunkType != ChunkType_JSON) {
+        throw DeadlyImportError("GLTF: JSON chunk missing");
+    }
+
+    // read the scene data, ensure null termination
+    static_assert(std::numeric_limits<uint32_t>::max() <= std::numeric_limits<size_t>::max(), "size_t must be at least 32bits");
+    mSceneLength = chunk.chunkLength; // Can't be larger than 4GB (max. uint32_t)
+    sceneData.resize(mSceneLength + 1);
+    sceneData[mSceneLength] = '\0';
+
+    if (stream.Read(&sceneData[0], 1, mSceneLength) != mSceneLength) {
+        throw DeadlyImportError("GLTF: Could not read the file contents");
+    }
+
+    uint32_t padding = ((chunk.chunkLength + 3) & ~3) - chunk.chunkLength;
+    if (padding > 0) {
+        stream.Seek(padding, aiOrigin_CUR);
+    }
+
+    AI_SWAP4(header.length);
+    mBodyOffset = 12 + 8 + chunk.chunkLength + padding + 8;
+    if (header.length >= mBodyOffset) {
+        if (stream.Read(&chunk, sizeof(chunk), 1) != 1) {
+            throw DeadlyImportError("GLTF: Unable to read BIN chunk");
+        }
+
+        AI_SWAP4(chunk.chunkLength);
+        AI_SWAP4(chunk.chunkType);
+
+        if (chunk.chunkType != ChunkType_BIN) {
+            throw DeadlyImportError("GLTF: BIN chunk missing");
+        }
+
+        mBodyLength = chunk.chunkLength;
+    } else {
+        mBodyOffset = mBodyLength = 0;
+    }
+}
+
+inline rapidjson::Document Asset::ReadDocument(IOStream &stream, bool isBinary, std::vector<char> &sceneData) {
+    ASSIMP_LOG_DEBUG("Loading GLTF2 asset");
+
+    // is binary? then read the header
+    if (isBinary) {
+        SetAsBinary(); // also creates the body buffer
+        ReadBinaryHeader(stream, sceneData);
+    } else {
+        mSceneLength = stream.FileSize();
+        mBodyLength = 0;
+
+        // Binary format only supports up to 4GB of JSON, use that as a maximum
+        if (mSceneLength >= std::numeric_limits<uint32_t>::max()) {
+            throw DeadlyImportError("GLTF: JSON size greater than 4GB");
+        }
+
+        // read the scene data, ensure null termination
+        sceneData.resize(mSceneLength + 1);
+        sceneData[mSceneLength] = '\0';
+
+        if (stream.Read(&sceneData[0], 1, mSceneLength) != mSceneLength) {
+            throw DeadlyImportError("GLTF: Could not read the file contents");
+        }
+    }
+
+    // Smallest legal JSON file is "{}" Smallest loadable glTF file is larger than that but catch it later
+    if (mSceneLength < 2) {
+        throw DeadlyImportError("GLTF: No JSON file contents");
+    }
+
+    // parse the JSON document
+    ASSIMP_LOG_DEBUG("Parsing GLTF2 JSON");
+    Document doc;
+    doc.ParseInsitu(&sceneData[0]);
+
+    if (doc.HasParseError()) {
+        char buffer[32];
+        ai_snprintf(buffer, 32, "%d", static_cast<int>(doc.GetErrorOffset()));
+        throw DeadlyImportError("GLTF: JSON parse error, offset ", buffer, ": ", GetParseError_En(doc.GetParseError()));
+    }
+
+    if (!doc.IsObject()) {
+        throw DeadlyImportError("GLTF: JSON document root must be a JSON object");
+    }
+
+    return doc;
+}
+
+inline void Asset::Load(const std::string &pFile, bool isBinary)
+{
+    mCurrentAssetDir.clear();
+    if (0 != strncmp(pFile.c_str(), AI_MEMORYIO_MAGIC_FILENAME, AI_MEMORYIO_MAGIC_FILENAME_LENGTH)) {
+        mCurrentAssetDir = glTFCommon::getCurrentAssetDir(pFile);
+    }
+
+    shared_ptr<IOStream> stream(OpenFile(pFile.c_str(), "rb", true));
+    if (!stream) {
+        throw DeadlyImportError("GLTF: Could not open file for reading");
+    }
+
+    std::vector<char> sceneData;
+    rapidjson::Document doc = ReadDocument(*stream, isBinary, sceneData);
+
+    // If a schemaDocumentProvider is available, see if the glTF schema is present. 
+    // If so, use it to validate the document.
+    if (mSchemaDocumentProvider) {
+        if (const rapidjson::SchemaDocument *gltfSchema = mSchemaDocumentProvider->GetRemoteDocument("glTF.schema.json", 16)) {
+            // The schemas are found here: https://github.com/KhronosGroup/glTF/tree/main/specification/2.0/schema
+            rapidjson::SchemaValidator validator(*gltfSchema);
+            if (!doc.Accept(validator)) {
+                rapidjson::StringBuffer pathBuffer;
+                validator.GetInvalidSchemaPointer().StringifyUriFragment(pathBuffer);
+                rapidjson::StringBuffer argumentBuffer;
+                validator.GetInvalidDocumentPointer().StringifyUriFragment(argumentBuffer);
+                throw DeadlyImportError("GLTF: The JSON document did not satisfy the glTF2 schema. Schema keyword: ", validator.GetInvalidSchemaKeyword(), ", document path: ", pathBuffer.GetString(), ", argument: ", argumentBuffer.GetString());
+            }
+        }
+    }
+
+    // Fill the buffer instance for the current file embedded contents
+    if (mBodyLength > 0) {
+        if (!mBodyBuffer->LoadFromStream(*stream, mBodyLength, mBodyOffset)) {
+            throw DeadlyImportError("GLTF: Unable to read gltf file");
+        }
+    }
+
+    // Load the metadata
+    asset.Read(doc);
+    ReadExtensionsUsed(doc);
+    ReadExtensionsRequired(doc);
+
+#ifndef ASSIMP_ENABLE_DRACO
+    // Is Draco required?
+    if (extensionsRequired.KHR_draco_mesh_compression) {
+        throw DeadlyImportError("GLTF: Draco mesh compression not supported.");
+    }
+#endif
+
+    // Prepare the dictionaries
+    for (size_t i = 0; i < mDicts.size(); ++i) {
+        mDicts[i]->AttachToDocument(doc);
+    }
+
+    // Read the "scene" property, which specifies which scene to load
+    // and recursively load everything referenced by it
+    unsigned int sceneIndex = 0;
+    Value *curScene = FindUInt(doc, "scene");
+    if (nullptr != curScene) {
+        sceneIndex = curScene->GetUint();
+    }
+
+    if (Value *scenesArray = FindArray(doc, "scenes")) {
+        if (sceneIndex < scenesArray->Size()) {
+            this->scene = scenes.Retrieve(sceneIndex);
+        }
+    }
+
+    if (Value *skinsArray = FindArray(doc, "skins")) {
+        for (unsigned int i = 0; i < skinsArray->Size(); ++i) {
+            skins.Retrieve(i);
+        }
+    }
+
+    if (Value *animsArray = FindArray(doc, "animations")) {
+        for (unsigned int i = 0; i < animsArray->Size(); ++i) {
+            animations.Retrieve(i);
+        }
+    }
+
+    // Clean up
+    for (size_t i = 0; i < mDicts.size(); ++i) {
+        mDicts[i]->DetachFromDocument();
+    }
+}
+
+inline bool Asset::CanRead(const std::string &pFile, bool isBinary) {
+    try {
+        shared_ptr<IOStream> stream(OpenFile(pFile.c_str(), "rb", true));
+        if (!stream) {
+            return false;
+        }
+        std::vector<char> sceneData;
+        rapidjson::Document doc = ReadDocument(*stream, isBinary, sceneData);
+        asset.Read(doc);
+    } catch (...) {
+        return false;
+    }
+    return true;
+}
+
+inline void Asset::SetAsBinary() {
+    if (!mBodyBuffer) {
+        mBodyBuffer = buffers.Create("binary_glTF");
+        mBodyBuffer->MarkAsSpecial();
+    }
+}
+
+// As required extensions are only a concept in glTF 2.0, this is here
+// instead of glTFCommon.h
+#define CHECK_REQUIRED_EXT(EXT) \
+    if (exts.find(#EXT) != exts.end()) extensionsRequired.EXT = true;
+
+inline void Asset::ReadExtensionsRequired(Document &doc) {
+    Value *extsRequired = FindArray(doc, "extensionsRequired");
+    if (nullptr == extsRequired) {
+        return;
+    }
+
+    std::gltf_unordered_map<std::string, bool> exts;
+    for (unsigned int i = 0; i < extsRequired->Size(); ++i) {
+        if ((*extsRequired)[i].IsString()) {
+            exts[(*extsRequired)[i].GetString()] = true;
+        }
+    }
+
+    CHECK_REQUIRED_EXT(KHR_draco_mesh_compression);
+
+#undef CHECK_REQUIRED_EXT
+}
+
+inline void Asset::ReadExtensionsUsed(Document &doc) {
+    Value *extsUsed = FindArray(doc, "extensionsUsed");
+    if (!extsUsed) return;
+
+    std::gltf_unordered_map<std::string, bool> exts;
+
+    for (unsigned int i = 0; i < extsUsed->Size(); ++i) {
+        if ((*extsUsed)[i].IsString()) {
+            exts[(*extsUsed)[i].GetString()] = true;
+        }
+    }
+
+    CHECK_EXT(KHR_materials_pbrSpecularGlossiness);
+    CHECK_EXT(KHR_materials_unlit);
+    CHECK_EXT(KHR_lights_punctual);
+    CHECK_EXT(KHR_texture_transform);
+    CHECK_EXT(KHR_materials_sheen);
+    CHECK_EXT(KHR_materials_clearcoat);
+    CHECK_EXT(KHR_materials_transmission);
+    CHECK_EXT(KHR_materials_volume);
+    CHECK_EXT(KHR_materials_ior);
+    CHECK_EXT(KHR_draco_mesh_compression);
+    CHECK_EXT(KHR_texture_basisu);
+
+#undef CHECK_EXT
+}
+
+inline IOStream *Asset::OpenFile(const std::string &path, const char *mode, bool /*absolute*/) {
+#ifdef ASSIMP_API
+    return mIOSystem->Open(path, mode);
+#else
+    if (path.size() < 2) return nullptr;
+    if (!absolute && path[1] != ':' && path[0] != '/') { // relative?
+        path = mCurrentAssetDir + path;
+    }
+    FILE *f = fopen(path.c_str(), mode);
+    return f ? new IOStream(f) : nullptr;
+#endif
+}
+
+inline std::string Asset::FindUniqueID(const std::string &str, const char *suffix) {
+    std::string id = str;
+
+    if (!id.empty()) {
+        if (mUsedIds.find(id) == mUsedIds.end())
+            return id;
+
+        id += "_";
+    }
+
+    id += suffix;
+
+    Asset::IdMap::iterator it = mUsedIds.find(id);
+    if (it == mUsedIds.end()) {
+        return id;
+    }
+
+    std::vector<char> buffer;
+    buffer.resize(id.size() + 16);
+    int offset = ai_snprintf(buffer.data(), buffer.size(), "%s_", id.c_str());
+    for (int i = 0; it != mUsedIds.end(); ++i) {
+        ai_snprintf(buffer.data() + offset, buffer.size() - offset, "%d", i);
+        id = buffer.data();
+        it = mUsedIds.find(id);
+    }
+
+    return id;
+}
+
+#if _MSC_VER
+#   pragma warning(pop)
+#endif // _MSC_VER
+
+} // namespace glTF2