add assimp submodule

1 files changed, 1637 insertions, 0 deletions

diff --git a/src/mesh/assimp-master/code/AssetLib/glTF2/glTF2Importer.cpp b/src/mesh/assimp-master/code/AssetLib/glTF2/glTF2Importer.cpp
new file mode 100644
index 0000000..1f4cafd
--- /dev/null
+++ b/src/mesh/assimp-master/code/AssetLib/glTF2/glTF2Importer.cpp
@@ -0,0 +1,1637 @@
+/*
+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.
+
+----------------------------------------------------------------------
+*/
+
+#if !defined(ASSIMP_BUILD_NO_GLTF_IMPORTER) && !defined(ASSIMP_BUILD_NO_GLTF2_IMPORTER)
+
+#include "AssetLib/glTF2/glTF2Importer.h"
+#include "PostProcessing/MakeVerboseFormat.h"
+#include "AssetLib/glTF2/glTF2Asset.h"
+
+#if !defined(ASSIMP_BUILD_NO_EXPORT)
+#include "AssetLib/glTF2/glTF2AssetWriter.h"
+#endif
+
+#include <assimp/CreateAnimMesh.h>
+#include <assimp/StringComparison.h>
+#include <assimp/StringUtils.h>
+#include <assimp/ai_assert.h>
+#include <assimp/importerdesc.h>
+#include <assimp/scene.h>
+#include <assimp/DefaultLogger.hpp>
+#include <assimp/Importer.hpp>
+#include <assimp/commonMetaData.h>
+#include <assimp/DefaultIOSystem.h>
+
+#include <memory>
+#include <unordered_map>
+
+#include <rapidjson/document.h>
+#include <rapidjson/rapidjson.h>
+
+using namespace Assimp;
+using namespace glTF2;
+using namespace glTFCommon;
+
+namespace {
+// generate bi-tangents from normals and tangents according to spec
+struct Tangent {
+    aiVector3D xyz;
+    ai_real w;
+};
+} // namespace
+
+//
+// glTF2Importer
+//
+
+static const aiImporterDesc desc = {
+    "glTF2 Importer",
+    "",
+    "",
+    "",
+    aiImporterFlags_SupportTextFlavour | aiImporterFlags_SupportBinaryFlavour | aiImporterFlags_LimitedSupport | aiImporterFlags_Experimental,
+    0,
+    0,
+    0,
+    0,
+    "gltf glb"
+};
+
+glTF2Importer::glTF2Importer() :
+        BaseImporter(),
+        meshOffsets(),
+        mEmbeddedTexIdxs(),
+        mScene(nullptr) {
+    // empty
+}
+
+glTF2Importer::~glTF2Importer() {
+    // empty
+}
+
+const aiImporterDesc *glTF2Importer::GetInfo() const {
+    return &desc;
+}
+
+bool glTF2Importer::CanRead(const std::string &filename, IOSystem *pIOHandler, bool checkSig ) const {
+    const std::string extension = GetExtension(filename);
+    if (!checkSig && (extension != "gltf") && (extension != "glb")) {
+        return false;
+    }
+
+    if (pIOHandler) {
+        glTF2::Asset asset(pIOHandler);
+        return asset.CanRead(filename, extension == "glb");
+    }
+
+    return false;
+}
+
+static inline aiTextureMapMode ConvertWrappingMode(SamplerWrap gltfWrapMode) {
+    switch (gltfWrapMode) {
+        case SamplerWrap::Mirrored_Repeat:
+            return aiTextureMapMode_Mirror;
+
+        case SamplerWrap::Clamp_To_Edge:
+            return aiTextureMapMode_Clamp;
+
+        case SamplerWrap::UNSET:
+        case SamplerWrap::Repeat:
+        default:
+            return aiTextureMapMode_Wrap;
+    }
+}
+
+static inline void SetMaterialColorProperty(Asset & /*r*/, vec4 &prop, aiMaterial *mat,
+        const char *pKey, unsigned int type, unsigned int idx) {
+    aiColor4D col;
+    CopyValue(prop, col);
+    mat->AddProperty(&col, 1, pKey, type, idx);
+}
+
+static inline void SetMaterialColorProperty(Asset & /*r*/, vec3 &prop, aiMaterial *mat,
+        const char *pKey, unsigned int type, unsigned int idx) {
+    aiColor4D col;
+    glTFCommon::CopyValue(prop, col);
+    mat->AddProperty(&col, 1, pKey, type, idx);
+}
+
+static void SetMaterialTextureProperty(std::vector<int> &embeddedTexIdxs, Asset & /*r*/,
+        glTF2::TextureInfo prop, aiMaterial *mat, aiTextureType texType,
+        unsigned int texSlot = 0) {
+    if (prop.texture && prop.texture->source) {
+        aiString uri(prop.texture->source->uri);
+
+        int texIdx = embeddedTexIdxs[prop.texture->source.GetIndex()];
+        if (texIdx != -1) { // embedded
+            // setup texture reference string (copied from ColladaLoader::FindFilenameForEffectTexture)
+            uri.data[0] = '*';
+            uri.length = 1 + ASSIMP_itoa10(uri.data + 1, MAXLEN - 1, texIdx);
+        }
+
+        mat->AddProperty(&uri, AI_MATKEY_TEXTURE(texType, texSlot));
+        const int uvIndex = static_cast<int>(prop.texCoord);
+        mat->AddProperty(&uvIndex, 1, AI_MATKEY_UVWSRC(texType, texSlot));
+
+        if (prop.textureTransformSupported) {
+            aiUVTransform transform;
+            transform.mScaling.x = prop.TextureTransformExt_t.scale[0];
+            transform.mScaling.y = prop.TextureTransformExt_t.scale[1];
+            transform.mRotation = -prop.TextureTransformExt_t.rotation; // must be negated
+
+            // A change of coordinates is required to map glTF UV transformations into the space used by
+            // Assimp. In glTF all UV origins are at 0,1 (top left of texture) in Assimp space. In Assimp
+            // rotation occurs around the image center (0.5,0.5) where as in glTF rotation is around the
+            // texture origin. All three can be corrected for solely by a change of the translation since
+            // the transformations available are shape preserving. Note the importer already flips the V
+            // coordinate of the actual meshes during import.
+            const ai_real rcos(cos(-transform.mRotation));
+            const ai_real rsin(sin(-transform.mRotation));
+            transform.mTranslation.x = (static_cast<ai_real>( 0.5 ) * transform.mScaling.x) * (-rcos + rsin + 1) + prop.TextureTransformExt_t.offset[0];
+            transform.mTranslation.y = ((static_cast<ai_real>( 0.5 ) * transform.mScaling.y) * (rsin + rcos - 1)) + 1 - transform.mScaling.y - prop.TextureTransformExt_t.offset[1];;
+
+            mat->AddProperty(&transform, 1, _AI_MATKEY_UVTRANSFORM_BASE, texType, texSlot);
+        }
+
+        if (prop.texture->sampler) {
+            Ref<Sampler> sampler = prop.texture->sampler;
+
+            aiString name(sampler->name);
+            aiString id(sampler->id);
+
+            mat->AddProperty(&name, AI_MATKEY_GLTF_MAPPINGNAME(texType, texSlot));
+            mat->AddProperty(&id, AI_MATKEY_GLTF_MAPPINGID(texType, texSlot));
+
+            aiTextureMapMode wrapS = ConvertWrappingMode(sampler->wrapS);
+            aiTextureMapMode wrapT = ConvertWrappingMode(sampler->wrapT);
+            mat->AddProperty(&wrapS, 1, AI_MATKEY_MAPPINGMODE_U(texType, texSlot));
+            mat->AddProperty(&wrapT, 1, AI_MATKEY_MAPPINGMODE_V(texType, texSlot));
+
+            if (sampler->magFilter != SamplerMagFilter::UNSET) {
+                mat->AddProperty(&sampler->magFilter, 1, AI_MATKEY_GLTF_MAPPINGFILTER_MAG(texType, texSlot));
+            }
+
+            if (sampler->minFilter != SamplerMinFilter::UNSET) {
+                mat->AddProperty(&sampler->minFilter, 1, AI_MATKEY_GLTF_MAPPINGFILTER_MIN(texType, texSlot));
+            }
+        } else {
+            // Use glTFv2 default sampler
+            const aiTextureMapMode default_wrap = aiTextureMapMode_Wrap;
+            mat->AddProperty(&default_wrap, 1, AI_MATKEY_MAPPINGMODE_U(texType, texSlot));
+            mat->AddProperty(&default_wrap, 1, AI_MATKEY_MAPPINGMODE_V(texType, texSlot));
+        }
+    }
+}
+
+inline void SetMaterialTextureProperty(std::vector<int> &embeddedTexIdxs, Asset &r,
+        NormalTextureInfo &prop, aiMaterial *mat, aiTextureType texType,
+        unsigned int texSlot = 0) {
+    SetMaterialTextureProperty(embeddedTexIdxs, r, (glTF2::TextureInfo)prop, mat, texType, texSlot);
+
+    if (prop.texture && prop.texture->source) {
+        mat->AddProperty(&prop.scale, 1, AI_MATKEY_GLTF_TEXTURE_SCALE(texType, texSlot));
+    }
+}
+
+inline void SetMaterialTextureProperty(std::vector<int> &embeddedTexIdxs, Asset &r,
+        OcclusionTextureInfo &prop, aiMaterial *mat, aiTextureType texType,
+        unsigned int texSlot = 0) {
+    SetMaterialTextureProperty(embeddedTexIdxs, r, (glTF2::TextureInfo)prop, mat, texType, texSlot);
+
+    if (prop.texture && prop.texture->source) {
+        mat->AddProperty(&prop.strength, 1, AI_MATKEY_GLTF_TEXTURE_STRENGTH(texType, texSlot));
+    }
+}
+
+static aiMaterial *ImportMaterial(std::vector<int> &embeddedTexIdxs, Asset &r, Material &mat) {
+    aiMaterial *aimat = new aiMaterial();
+
+    try {
+        if (!mat.name.empty()) {
+            aiString str(mat.name);
+
+            aimat->AddProperty(&str, AI_MATKEY_NAME);
+        }
+
+        // Set Assimp DIFFUSE and BASE COLOR to the pbrMetallicRoughness base color and texture for backwards compatibility
+        // Technically should not load any pbrMetallicRoughness if extensionsRequired contains KHR_materials_pbrSpecularGlossiness
+        SetMaterialColorProperty(r, mat.pbrMetallicRoughness.baseColorFactor, aimat, AI_MATKEY_COLOR_DIFFUSE);
+        SetMaterialColorProperty(r, mat.pbrMetallicRoughness.baseColorFactor, aimat, AI_MATKEY_BASE_COLOR);
+
+        SetMaterialTextureProperty(embeddedTexIdxs, r, mat.pbrMetallicRoughness.baseColorTexture, aimat, aiTextureType_DIFFUSE);
+        SetMaterialTextureProperty(embeddedTexIdxs, r, mat.pbrMetallicRoughness.baseColorTexture, aimat, aiTextureType_BASE_COLOR);
+
+        SetMaterialTextureProperty(embeddedTexIdxs, r, mat.pbrMetallicRoughness.metallicRoughnessTexture, aimat, AI_MATKEY_GLTF_PBRMETALLICROUGHNESS_METALLICROUGHNESS_TEXTURE);
+
+        aimat->AddProperty(&mat.pbrMetallicRoughness.metallicFactor, 1, AI_MATKEY_METALLIC_FACTOR);
+        aimat->AddProperty(&mat.pbrMetallicRoughness.roughnessFactor, 1, AI_MATKEY_ROUGHNESS_FACTOR);
+
+        float roughnessAsShininess = 1 - mat.pbrMetallicRoughness.roughnessFactor;
+        roughnessAsShininess *= roughnessAsShininess * 1000;
+        aimat->AddProperty(&roughnessAsShininess, 1, AI_MATKEY_SHININESS);
+
+        SetMaterialTextureProperty(embeddedTexIdxs, r, mat.normalTexture, aimat, aiTextureType_NORMALS);
+        SetMaterialTextureProperty(embeddedTexIdxs, r, mat.occlusionTexture, aimat, aiTextureType_LIGHTMAP);
+        SetMaterialTextureProperty(embeddedTexIdxs, r, mat.emissiveTexture, aimat, aiTextureType_EMISSIVE);
+        SetMaterialColorProperty(r, mat.emissiveFactor, aimat, AI_MATKEY_COLOR_EMISSIVE);
+
+        aimat->AddProperty(&mat.doubleSided, 1, AI_MATKEY_TWOSIDED);
+        aimat->AddProperty(&mat.pbrMetallicRoughness.baseColorFactor[3], 1, AI_MATKEY_OPACITY);
+
+        aiString alphaMode(mat.alphaMode);
+        aimat->AddProperty(&alphaMode, AI_MATKEY_GLTF_ALPHAMODE);
+        aimat->AddProperty(&mat.alphaCutoff, 1, AI_MATKEY_GLTF_ALPHACUTOFF);
+
+        //pbrSpecularGlossiness
+        if (mat.pbrSpecularGlossiness.isPresent) {
+            PbrSpecularGlossiness &pbrSG = mat.pbrSpecularGlossiness.value;
+
+            SetMaterialColorProperty(r, pbrSG.diffuseFactor, aimat, AI_MATKEY_COLOR_DIFFUSE);
+            SetMaterialColorProperty(r, pbrSG.specularFactor, aimat, AI_MATKEY_COLOR_SPECULAR);
+
+            float glossinessAsShininess = pbrSG.glossinessFactor * 1000.0f;
+            aimat->AddProperty(&glossinessAsShininess, 1, AI_MATKEY_SHININESS);
+            aimat->AddProperty(&pbrSG.glossinessFactor, 1, AI_MATKEY_GLOSSINESS_FACTOR);
+
+            SetMaterialTextureProperty(embeddedTexIdxs, r, pbrSG.diffuseTexture, aimat, aiTextureType_DIFFUSE);
+
+            SetMaterialTextureProperty(embeddedTexIdxs, r, pbrSG.specularGlossinessTexture, aimat, aiTextureType_SPECULAR);
+        }
+
+        // glTFv2 is either PBR or Unlit
+        aiShadingMode shadingMode = aiShadingMode_PBR_BRDF;
+        if (mat.unlit) {
+            aimat->AddProperty(&mat.unlit, 1, "$mat.gltf.unlit", 0, 0); // TODO: Remove this property, it is kept for backwards compatibility with assimp 5.0.1
+            shadingMode = aiShadingMode_Unlit;
+        }
+
+        aimat->AddProperty(&shadingMode, 1, AI_MATKEY_SHADING_MODEL);
+
+
+        // KHR_materials_sheen
+        if (mat.materialSheen.isPresent) {
+            MaterialSheen &sheen = mat.materialSheen.value;
+            // Default value {0,0,0} disables Sheen
+            if (std::memcmp(sheen.sheenColorFactor, defaultSheenFactor, sizeof(glTFCommon::vec3)) != 0) {
+                SetMaterialColorProperty(r, sheen.sheenColorFactor, aimat, AI_MATKEY_SHEEN_COLOR_FACTOR);
+                aimat->AddProperty(&sheen.sheenRoughnessFactor, 1, AI_MATKEY_SHEEN_ROUGHNESS_FACTOR);
+                SetMaterialTextureProperty(embeddedTexIdxs, r, sheen.sheenColorTexture, aimat, AI_MATKEY_SHEEN_COLOR_TEXTURE);
+                SetMaterialTextureProperty(embeddedTexIdxs, r, sheen.sheenRoughnessTexture, aimat, AI_MATKEY_SHEEN_ROUGHNESS_TEXTURE);
+            }
+        }
+
+        // KHR_materials_clearcoat
+        if (mat.materialClearcoat.isPresent) {
+            MaterialClearcoat &clearcoat = mat.materialClearcoat.value;
+            // Default value 0.0 disables clearcoat
+            if (clearcoat.clearcoatFactor != 0.0f) {
+                aimat->AddProperty(&clearcoat.clearcoatFactor, 1, AI_MATKEY_CLEARCOAT_FACTOR);
+                aimat->AddProperty(&clearcoat.clearcoatRoughnessFactor, 1, AI_MATKEY_CLEARCOAT_ROUGHNESS_FACTOR);
+                SetMaterialTextureProperty(embeddedTexIdxs, r, clearcoat.clearcoatTexture, aimat, AI_MATKEY_CLEARCOAT_TEXTURE);
+                SetMaterialTextureProperty(embeddedTexIdxs, r, clearcoat.clearcoatRoughnessTexture, aimat, AI_MATKEY_CLEARCOAT_ROUGHNESS_TEXTURE);
+                SetMaterialTextureProperty(embeddedTexIdxs, r, clearcoat.clearcoatNormalTexture, aimat, AI_MATKEY_CLEARCOAT_NORMAL_TEXTURE);
+            }
+        }
+
+        // KHR_materials_transmission
+        if (mat.materialTransmission.isPresent) {
+            MaterialTransmission &transmission = mat.materialTransmission.value;
+
+            aimat->AddProperty(&transmission.transmissionFactor, 1, AI_MATKEY_TRANSMISSION_FACTOR);
+            SetMaterialTextureProperty(embeddedTexIdxs, r, transmission.transmissionTexture, aimat, AI_MATKEY_TRANSMISSION_TEXTURE);
+        }
+
+        // KHR_materials_volume
+        if (mat.materialVolume.isPresent) {
+            MaterialVolume &volume = mat.materialVolume.value;
+
+            aimat->AddProperty(&volume.thicknessFactor, 1, AI_MATKEY_VOLUME_THICKNESS_FACTOR);
+            SetMaterialTextureProperty(embeddedTexIdxs, r, volume.thicknessTexture, aimat, AI_MATKEY_VOLUME_THICKNESS_TEXTURE);
+            aimat->AddProperty(&volume.attenuationDistance, 1, AI_MATKEY_VOLUME_ATTENUATION_DISTANCE);
+            SetMaterialColorProperty(r, volume.attenuationColor, aimat, AI_MATKEY_VOLUME_ATTENUATION_COLOR);
+        }
+
+        // KHR_materials_ior
+        if (mat.materialIOR.isPresent) {
+            MaterialIOR &ior = mat.materialIOR.value;
+
+            aimat->AddProperty(&ior.ior, 1, AI_MATKEY_REFRACTI);
+        }
+
+        return aimat;
+    } catch (...) {
+        delete aimat;
+        throw;
+    }
+}
+
+void glTF2Importer::ImportMaterials(Asset &r) {
+    const unsigned int numImportedMaterials = unsigned(r.materials.Size());
+    ASSIMP_LOG_DEBUG("Importing ", numImportedMaterials, " materials");
+    Material defaultMaterial;
+
+    mScene->mNumMaterials = numImportedMaterials + 1;
+    mScene->mMaterials = new aiMaterial *[mScene->mNumMaterials];
+    std::fill(mScene->mMaterials, mScene->mMaterials + mScene->mNumMaterials, nullptr);
+    mScene->mMaterials[numImportedMaterials] = ImportMaterial(mEmbeddedTexIdxs, r, defaultMaterial);
+
+    for (unsigned int i = 0; i < numImportedMaterials; ++i) {
+        mScene->mMaterials[i] = ImportMaterial(mEmbeddedTexIdxs, r, r.materials[i]);
+    }
+}
+
+static inline void SetFaceAndAdvance1(aiFace*& face, unsigned int numVertices, unsigned int a) {
+    if (a >= numVertices) {
+        return;
+    }
+    face->mNumIndices = 1;
+    face->mIndices = new unsigned int[1];
+    face->mIndices[0] = a;
+    ++face;
+}
+
+static inline void SetFaceAndAdvance2(aiFace*& face, unsigned int numVertices,
+        unsigned int a, unsigned int b) {
+    if ((a >= numVertices) || (b >= numVertices)) {
+        return;
+    }
+    face->mNumIndices = 2;
+    face->mIndices = new unsigned int[2];
+    face->mIndices[0] = a;
+    face->mIndices[1] = b;
+    ++face;
+}
+
+static inline void SetFaceAndAdvance3(aiFace*& face, unsigned int numVertices, unsigned int a,
+        unsigned int b, unsigned int c) {
+    if ((a >= numVertices) || (b >= numVertices) || (c >= numVertices)) {
+        return;
+    }
+    face->mNumIndices = 3;
+    face->mIndices = new unsigned int[3];
+    face->mIndices[0] = a;
+    face->mIndices[1] = b;
+    face->mIndices[2] = c;
+    ++face;
+}
+
+#ifdef ASSIMP_BUILD_DEBUG
+static inline bool CheckValidFacesIndices(aiFace *faces, unsigned nFaces, unsigned nVerts) {
+    for (unsigned i = 0; i < nFaces; ++i) {
+        for (unsigned j = 0; j < faces[i].mNumIndices; ++j) {
+            unsigned idx = faces[i].mIndices[j];
+            if (idx >= nVerts) {
+                return false;
+            }
+        }
+    }
+    return true;
+}
+#endif // ASSIMP_BUILD_DEBUG
+
+template<typename T>
+aiColor4D* GetVertexColorsForType(Ref<Accessor> input) {
+    constexpr float max = std::numeric_limits<T>::max();
+    aiColor4t<T>* colors;
+    input->ExtractData(colors);
+    auto output = new aiColor4D[input->count];
+    for (size_t i = 0; i < input->count; i++) {
+        output[i] = aiColor4D(
+            colors[i].r / max, colors[i].g / max,
+            colors[i].b / max, colors[i].a / max
+        );
+    }
+    delete[] colors;
+    return output;
+}
+
+void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
+    ASSIMP_LOG_DEBUG("Importing ", r.meshes.Size(), " meshes");
+    std::vector<std::unique_ptr<aiMesh>> meshes;
+
+    unsigned int k = 0;
+    meshOffsets.clear();
+
+    for (unsigned int m = 0; m < r.meshes.Size(); ++m) {
+        Mesh &mesh = r.meshes[m];
+
+        meshOffsets.push_back(k);
+        k += unsigned(mesh.primitives.size());
+
+        for (unsigned int p = 0; p < mesh.primitives.size(); ++p) {
+            Mesh::Primitive &prim = mesh.primitives[p];
+
+            aiMesh *aim = new aiMesh();
+            meshes.push_back(std::unique_ptr<aiMesh>(aim));
+
+            aim->mName = mesh.name.empty() ? mesh.id : mesh.name;
+
+            if (mesh.primitives.size() > 1) {
+                ai_uint32 &len = aim->mName.length;
+                aim->mName.data[len] = '-';
+                len += 1 + ASSIMP_itoa10(aim->mName.data + len + 1, unsigned(MAXLEN - len - 1), p);
+            }
+
+            switch (prim.mode) {
+                case PrimitiveMode_POINTS:
+                    aim->mPrimitiveTypes |= aiPrimitiveType_POINT;
+                    break;
+
+                case PrimitiveMode_LINES:
+                case PrimitiveMode_LINE_LOOP:
+                case PrimitiveMode_LINE_STRIP:
+                    aim->mPrimitiveTypes |= aiPrimitiveType_LINE;
+                    break;
+
+                case PrimitiveMode_TRIANGLES:
+                case PrimitiveMode_TRIANGLE_STRIP:
+                case PrimitiveMode_TRIANGLE_FAN:
+                    aim->mPrimitiveTypes |= aiPrimitiveType_TRIANGLE;
+                    break;
+            }
+
+            Mesh::Primitive::Attributes &attr = prim.attributes;
+
+            if (!attr.position.empty() && attr.position[0]) {
+                aim->mNumVertices = static_cast<unsigned int>(attr.position[0]->count);
+                attr.position[0]->ExtractData(aim->mVertices);
+            }
+
+            if (!attr.normal.empty() && attr.normal[0]) {
+                if (attr.normal[0]->count != aim->mNumVertices) {
+                    DefaultLogger::get()->warn("Normal count in mesh \"", mesh.name, "\" does not match the vertex count, normals ignored.");
+                } else {
+                    attr.normal[0]->ExtractData(aim->mNormals);
+
+                    // only extract tangents if normals are present
+                    if (!attr.tangent.empty() && attr.tangent[0]) {
+                        if (attr.tangent[0]->count != aim->mNumVertices) {
+                            DefaultLogger::get()->warn("Tangent count in mesh \"", mesh.name, "\" does not match the vertex count, tangents ignored.");
+                        } else {
+                            // generate bitangents from normals and tangents according to spec
+                            Tangent *tangents = nullptr;
+
+                            attr.tangent[0]->ExtractData(tangents);
+
+                            aim->mTangents = new aiVector3D[aim->mNumVertices];
+                            aim->mBitangents = new aiVector3D[aim->mNumVertices];
+
+                            for (unsigned int i = 0; i < aim->mNumVertices; ++i) {
+                                aim->mTangents[i] = tangents[i].xyz;
+                                aim->mBitangents[i] = (aim->mNormals[i] ^ tangents[i].xyz) * tangents[i].w;
+                            }
+
+                            delete[] tangents;
+                        }
+                    }
+                }
+            }
+
+            for (size_t c = 0; c < attr.color.size() && c < AI_MAX_NUMBER_OF_COLOR_SETS; ++c) {
+                if (attr.color[c]->count != aim->mNumVertices) {
+                    DefaultLogger::get()->warn("Color stream size in mesh \"", mesh.name,
+                                               "\" does not match the vertex count");
+                    continue;
+                }
+
+                auto componentType = attr.color[c]->componentType;
+                if (componentType == glTF2::ComponentType_FLOAT) {
+                    attr.color[c]->ExtractData(aim->mColors[c]);
+                } else {
+                    if (componentType == glTF2::ComponentType_UNSIGNED_BYTE) {
+                        aim->mColors[c] = GetVertexColorsForType<unsigned char>(attr.color[c]);
+                    } else if (componentType == glTF2::ComponentType_UNSIGNED_SHORT) {
+                        aim->mColors[c] = GetVertexColorsForType<unsigned short>(attr.color[c]);
+                    }
+                }
+            }
+            for (size_t tc = 0; tc < attr.texcoord.size() && tc < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++tc) {
+                if (!attr.texcoord[tc]) {
+                    DefaultLogger::get()->warn("Texture coordinate accessor not found or non-contiguous texture coordinate sets.");
+                    continue;
+                }
+
+                if (attr.texcoord[tc]->count != aim->mNumVertices) {
+                    DefaultLogger::get()->warn("Texcoord stream size in mesh \"", mesh.name,
+                                               "\" does not match the vertex count");
+                    continue;
+                }
+
+                attr.texcoord[tc]->ExtractData(aim->mTextureCoords[tc]);
+                aim->mNumUVComponents[tc] = attr.texcoord[tc]->GetNumComponents();
+
+                aiVector3D *values = aim->mTextureCoords[tc];
+                for (unsigned int i = 0; i < aim->mNumVertices; ++i) {
+                    values[i].y = 1 - values[i].y; // Flip Y coords
+                }
+            }
+
+            std::vector<Mesh::Primitive::Target> &targets = prim.targets;
+            if (!targets.empty()) {
+                aim->mNumAnimMeshes = (unsigned int)targets.size();
+                aim->mAnimMeshes = new aiAnimMesh *[aim->mNumAnimMeshes];
+                std::fill(aim->mAnimMeshes, aim->mAnimMeshes + aim->mNumAnimMeshes, nullptr);
+                for (size_t i = 0; i < targets.size(); i++) {
+                    bool needPositions = targets[i].position.size() > 0;
+                    bool needNormals = (targets[i].normal.size() > 0) && aim->HasNormals();
+                    bool needTangents = (targets[i].tangent.size() > 0) && aim->HasTangentsAndBitangents();
+                    // GLTF morph does not support colors and texCoords
+                    aim->mAnimMeshes[i] = aiCreateAnimMesh(aim,
+                            needPositions, needNormals, needTangents, false, false);
+                    aiAnimMesh &aiAnimMesh = *(aim->mAnimMeshes[i]);
+                    Mesh::Primitive::Target &target = targets[i];
+
+                    if (needPositions) {
+                        if (target.position[0]->count != aim->mNumVertices) {
+                            ASSIMP_LOG_WARN("Positions of target ", i, " in mesh \"", mesh.name, "\" does not match the vertex count");
+                        } else {
+                            aiVector3D *positionDiff = nullptr;
+                            target.position[0]->ExtractData(positionDiff);
+                            for (unsigned int vertexId = 0; vertexId < aim->mNumVertices; vertexId++) {
+                                aiAnimMesh.mVertices[vertexId] += positionDiff[vertexId];
+                            }
+                            delete[] positionDiff;
+                        }
+                    }
+                    if (needNormals) {
+                        if (target.normal[0]->count != aim->mNumVertices) {
+                            ASSIMP_LOG_WARN("Normals of target ", i, " in mesh \"", mesh.name, "\" does not match the vertex count");
+                        } else {
+                            aiVector3D *normalDiff = nullptr;
+                            target.normal[0]->ExtractData(normalDiff);
+                            for (unsigned int vertexId = 0; vertexId < aim->mNumVertices; vertexId++) {
+                                aiAnimMesh.mNormals[vertexId] += normalDiff[vertexId];
+                            }
+                            delete[] normalDiff;
+                        }
+                    }
+                    if (needTangents) {
+                        if (target.tangent[0]->count != aim->mNumVertices) {
+                            ASSIMP_LOG_WARN("Tangents of target ", i, " in mesh \"", mesh.name, "\" does not match the vertex count");
+                        } else {
+                            Tangent *tangent = nullptr;
+                            attr.tangent[0]->ExtractData(tangent);
+
+                            aiVector3D *tangentDiff = nullptr;
+                            target.tangent[0]->ExtractData(tangentDiff);
+
+                            for (unsigned int vertexId = 0; vertexId < aim->mNumVertices; ++vertexId) {
+                                tangent[vertexId].xyz += tangentDiff[vertexId];
+                                aiAnimMesh.mTangents[vertexId] = tangent[vertexId].xyz;
+                                aiAnimMesh.mBitangents[vertexId] = (aiAnimMesh.mNormals[vertexId] ^ tangent[vertexId].xyz) * tangent[vertexId].w;
+                            }
+                            delete[] tangent;
+                            delete[] tangentDiff;
+                        }
+                    }
+                    if (mesh.weights.size() > i) {
+                        aiAnimMesh.mWeight = mesh.weights[i];
+                    }
+                    if (mesh.targetNames.size() > i) {
+                        aiAnimMesh.mName = mesh.targetNames[i];
+                    }
+                }
+            }
+
+            aiFace *faces = nullptr;
+            aiFace *facePtr = nullptr;
+            size_t nFaces = 0;
+
+            if (prim.indices) {
+                size_t count = prim.indices->count;
+
+                Accessor::Indexer data = prim.indices->GetIndexer();
+                if (!data.IsValid()) {
+                    throw DeadlyImportError("GLTF: Invalid accessor without data in mesh ", getContextForErrorMessages(mesh.id, mesh.name));
+                }
+
+                switch (prim.mode) {
+                    case PrimitiveMode_POINTS: {
+                        nFaces = count;
+                        facePtr = faces = new aiFace[nFaces];
+                        for (unsigned int i = 0; i < count; ++i) {
+                            SetFaceAndAdvance1(facePtr, aim->mNumVertices, data.GetUInt(i));
+                        }
+                        break;
+                    }
+
+                    case PrimitiveMode_LINES: {
+                        nFaces = count / 2;
+                        if (nFaces * 2 != count) {
+                            ASSIMP_LOG_WARN("The number of vertices was not compatible with the LINES mode. Some vertices were dropped.");
+                            count = nFaces * 2;
+                        }
+                        facePtr = faces = new aiFace[nFaces];
+                        for (unsigned int i = 0; i < count; i += 2) {
+                            SetFaceAndAdvance2(facePtr, aim->mNumVertices, data.GetUInt(i), data.GetUInt(i + 1));
+                        }
+                        break;
+                    }
+
+                    case PrimitiveMode_LINE_LOOP:
+                    case PrimitiveMode_LINE_STRIP: {
+                        nFaces = count - ((prim.mode == PrimitiveMode_LINE_STRIP) ? 1 : 0);
+                        facePtr = faces = new aiFace[nFaces];
+                        SetFaceAndAdvance2(facePtr, aim->mNumVertices, data.GetUInt(0), data.GetUInt(1));
+                        for (unsigned int i = 2; i < count; ++i) {
+                            SetFaceAndAdvance2(facePtr, aim->mNumVertices, data.GetUInt(i - 1), data.GetUInt(i));
+                        }
+                        if (prim.mode == PrimitiveMode_LINE_LOOP) { // close the loop
+                            SetFaceAndAdvance2(facePtr, aim->mNumVertices, data.GetUInt(static_cast<int>(count) - 1), faces[0].mIndices[0]);
+                        }
+                        break;
+                    }
+
+                    case PrimitiveMode_TRIANGLES: {
+                        nFaces = count / 3;
+                        if (nFaces * 3 != count) {
+                            ASSIMP_LOG_WARN("The number of vertices was not compatible with the TRIANGLES mode. Some vertices were dropped.");
+                            count = nFaces * 3;
+                        }
+                        facePtr = faces = new aiFace[nFaces];
+                        for (unsigned int i = 0; i < count; i += 3) {
+                            SetFaceAndAdvance3(facePtr, aim->mNumVertices, data.GetUInt(i), data.GetUInt(i + 1), data.GetUInt(i + 2));
+                        }
+                        break;
+                    }
+                    case PrimitiveMode_TRIANGLE_STRIP: {
+                        nFaces = count - 2;
+                        facePtr = faces = new aiFace[nFaces];
+                        for (unsigned int i = 0; i < nFaces; ++i) {
+                            //The ordering is to ensure that the triangles are all drawn with the same orientation
+                            if ((i + 1) % 2 == 0) {
+                                //For even n, vertices n + 1, n, and n + 2 define triangle n
+                                SetFaceAndAdvance3(facePtr, aim->mNumVertices, data.GetUInt(i + 1), data.GetUInt(i), data.GetUInt(i + 2));
+                            } else {
+                                //For odd n, vertices n, n+1, and n+2 define triangle n
+                                SetFaceAndAdvance3(facePtr, aim->mNumVertices, data.GetUInt(i), data.GetUInt(i + 1), data.GetUInt(i + 2));
+                            }
+                        }
+                        break;
+                    }
+                    case PrimitiveMode_TRIANGLE_FAN:
+                        nFaces = count - 2;
+                        facePtr = faces = new aiFace[nFaces];
+                        SetFaceAndAdvance3(facePtr, aim->mNumVertices, data.GetUInt(0), data.GetUInt(1), data.GetUInt(2));
+                        for (unsigned int i = 1; i < nFaces; ++i) {
+                            SetFaceAndAdvance3(facePtr, aim->mNumVertices, data.GetUInt(0), data.GetUInt(i + 1), data.GetUInt(i + 2));
+                        }
+                        break;
+                }
+            } else { // no indices provided so directly generate from counts
+
+                // use the already determined count as it includes checks
+                unsigned int count = aim->mNumVertices;
+
+                switch (prim.mode) {
+                    case PrimitiveMode_POINTS: {
+                        nFaces = count;
+                        facePtr = faces = new aiFace[nFaces];
+                        for (unsigned int i = 0; i < count; ++i) {
+                            SetFaceAndAdvance1(facePtr, aim->mNumVertices, i);
+                        }
+                        break;
+                    }
+
+                    case PrimitiveMode_LINES: {
+                        nFaces = count / 2;
+                        if (nFaces * 2 != count) {
+                            ASSIMP_LOG_WARN("The number of vertices was not compatible with the LINES mode. Some vertices were dropped.");
+                            count = (unsigned int)nFaces * 2;
+                        }
+                        facePtr = faces = new aiFace[nFaces];
+                        for (unsigned int i = 0; i < count; i += 2) {
+                            SetFaceAndAdvance2(facePtr, aim->mNumVertices, i, i + 1);
+                        }
+                        break;
+                    }
+
+                    case PrimitiveMode_LINE_LOOP:
+                    case PrimitiveMode_LINE_STRIP: {
+                        nFaces = count - ((prim.mode == PrimitiveMode_LINE_STRIP) ? 1 : 0);
+                        facePtr = faces = new aiFace[nFaces];
+                        SetFaceAndAdvance2(facePtr, aim->mNumVertices, 0, 1);
+                        for (unsigned int i = 2; i < count; ++i) {
+                            SetFaceAndAdvance2(facePtr, aim->mNumVertices, i - 1, i);
+                        }
+                        if (prim.mode == PrimitiveMode_LINE_LOOP) { // close the loop
+                            SetFaceAndAdvance2(facePtr, aim->mNumVertices, count - 1, 0);
+                        }
+                        break;
+                    }
+
+                    case PrimitiveMode_TRIANGLES: {
+                        nFaces = count / 3;
+                        if (nFaces * 3 != count) {
+                            ASSIMP_LOG_WARN("The number of vertices was not compatible with the TRIANGLES mode. Some vertices were dropped.");
+                            count = (unsigned int)nFaces * 3;
+                        }
+                        facePtr = faces = new aiFace[nFaces];
+                        for (unsigned int i = 0; i < count; i += 3) {
+                            SetFaceAndAdvance3(facePtr, aim->mNumVertices, i, i + 1, i + 2);
+                        }
+                        break;
+                    }
+                    case PrimitiveMode_TRIANGLE_STRIP: {
+                        nFaces = count - 2;
+                        facePtr = faces = new aiFace[nFaces];
+                        for (unsigned int i = 0; i < nFaces; ++i) {
+                            //The ordering is to ensure that the triangles are all drawn with the same orientation
+                            if ((i + 1) % 2 == 0) {
+                                //For even n, vertices n + 1, n, and n + 2 define triangle n
+                                SetFaceAndAdvance3(facePtr, aim->mNumVertices, i + 1, i, i + 2);
+                            } else {
+                                //For odd n, vertices n, n+1, and n+2 define triangle n
+                                SetFaceAndAdvance3(facePtr, aim->mNumVertices, i, i + 1, i + 2);
+                            }
+                        }
+                        break;
+                    }
+                    case PrimitiveMode_TRIANGLE_FAN:
+                        nFaces = count - 2;
+                        facePtr = faces = new aiFace[nFaces];
+                        SetFaceAndAdvance3(facePtr, aim->mNumVertices, 0, 1, 2);
+                        for (unsigned int i = 1; i < nFaces; ++i) {
+                            SetFaceAndAdvance3(facePtr, aim->mNumVertices, 0, i + 1, i + 2);
+                        }
+                        break;
+                }
+            }
+
+            if (faces) {
+                aim->mFaces = faces;
+                const unsigned int actualNumFaces = static_cast<unsigned int>(facePtr - faces);
+                if (actualNumFaces < nFaces) {
+                    ASSIMP_LOG_WARN("Some faces had out-of-range indices. Those faces were dropped.");
+                }
+                if (actualNumFaces == 0) {
+                    throw DeadlyImportError("Mesh \"", aim->mName.C_Str(), "\" has no faces");
+                }
+                aim->mNumFaces = actualNumFaces;
+                ai_assert(CheckValidFacesIndices(faces, actualNumFaces, aim->mNumVertices));
+            }
+
+            if (prim.material) {
+                aim->mMaterialIndex = prim.material.GetIndex();
+            } else {
+                aim->mMaterialIndex = mScene->mNumMaterials - 1;
+            }
+        }
+    }
+
+    meshOffsets.push_back(k);
+
+    CopyVector(meshes, mScene->mMeshes, mScene->mNumMeshes);
+}
+
+void glTF2Importer::ImportCameras(glTF2::Asset &r) {
+    if (!r.cameras.Size()) {
+        return;
+    }
+
+    const unsigned int numCameras = r.cameras.Size();
+    ASSIMP_LOG_DEBUG("Importing ", numCameras, " cameras");
+    mScene->mNumCameras = numCameras;
+    mScene->mCameras = new aiCamera *[numCameras];
+    std::fill(mScene->mCameras, mScene->mCameras + numCameras, nullptr);
+
+    for (size_t i = 0; i < numCameras; ++i) {
+        Camera &cam = r.cameras[i];
+
+        aiCamera *aicam = mScene->mCameras[i] = new aiCamera();
+
+        // cameras point in -Z by default, rest is specified in node transform
+        aicam->mLookAt = aiVector3D(0.f, 0.f, -1.f);
+
+        if (cam.type == Camera::Perspective) {
+            aicam->mAspect = cam.cameraProperties.perspective.aspectRatio;
+            aicam->mHorizontalFOV = cam.cameraProperties.perspective.yfov * ((aicam->mAspect == 0.f) ? 1.f : aicam->mAspect);
+            aicam->mClipPlaneFar = cam.cameraProperties.perspective.zfar;
+            aicam->mClipPlaneNear = cam.cameraProperties.perspective.znear;
+        } else {
+            aicam->mClipPlaneFar = cam.cameraProperties.ortographic.zfar;
+            aicam->mClipPlaneNear = cam.cameraProperties.ortographic.znear;
+            aicam->mHorizontalFOV = 0.0;
+            aicam->mOrthographicWidth = cam.cameraProperties.ortographic.xmag;
+            aicam->mAspect = 1.0f;
+            if (0.f != cam.cameraProperties.ortographic.ymag) {
+                aicam->mAspect = cam.cameraProperties.ortographic.xmag / cam.cameraProperties.ortographic.ymag;
+            }
+        }
+    }
+}
+
+void glTF2Importer::ImportLights(glTF2::Asset &r) {
+    if (!r.lights.Size()) {
+        return;
+    }
+
+    const unsigned int numLights = r.lights.Size();
+    ASSIMP_LOG_DEBUG("Importing ", numLights, " lights");
+    mScene->mNumLights = numLights;
+    mScene->mLights = new aiLight *[numLights];
+    std::fill(mScene->mLights, mScene->mLights + numLights, nullptr);
+
+    for (size_t i = 0; i < numLights; ++i) {
+        Light &light = r.lights[i];
+
+        aiLight *ail = mScene->mLights[i] = new aiLight();
+
+        switch (light.type) {
+            case Light::Directional:
+                ail->mType = aiLightSource_DIRECTIONAL;
+                break;
+            case Light::Point:
+                ail->mType = aiLightSource_POINT;
+                break;
+            case Light::Spot:
+                ail->mType = aiLightSource_SPOT;
+                break;
+        }
+
+        if (ail->mType != aiLightSource_POINT) {
+            ail->mDirection = aiVector3D(0.0f, 0.0f, -1.0f);
+            ail->mUp = aiVector3D(0.0f, 1.0f, 0.0f);
+        }
+
+        vec3 colorWithIntensity = { light.color[0] * light.intensity, light.color[1] * light.intensity, light.color[2] * light.intensity };
+        CopyValue(colorWithIntensity, ail->mColorAmbient);
+        CopyValue(colorWithIntensity, ail->mColorDiffuse);
+        CopyValue(colorWithIntensity, ail->mColorSpecular);
+
+        if (ail->mType == aiLightSource_DIRECTIONAL) {
+            ail->mAttenuationConstant = 1.0;
+            ail->mAttenuationLinear = 0.0;
+            ail->mAttenuationQuadratic = 0.0;
+        } else {
+            //in PBR attenuation is calculated using inverse square law which can be expressed
+            //using assimps equation: 1/(att0 + att1 * d + att2 * d*d) with the following parameters
+            //this is correct equation for the case when range (see
+            //https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual)
+            //is not present. When range is not present it is assumed that it is infinite and so numerator is 1.
+            //When range is present then numerator might be any value in range [0,1] and then assimps equation
+            //will not suffice. In this case range is added into metadata in ImportNode function
+            //and its up to implementation to read it when it wants to
+            ail->mAttenuationConstant = 0.0;
+            ail->mAttenuationLinear = 0.0;
+            ail->mAttenuationQuadratic = 1.0;
+        }
+
+        if (ail->mType == aiLightSource_SPOT) {
+            ail->mAngleInnerCone = light.innerConeAngle;
+            ail->mAngleOuterCone = light.outerConeAngle;
+        }
+    }
+}
+
+static void GetNodeTransform(aiMatrix4x4 &matrix, const glTF2::Node &node) {
+    if (node.matrix.isPresent) {
+        CopyValue(node.matrix.value, matrix);
+        return;
+    } 
+
+    if (node.translation.isPresent) {
+        aiVector3D trans;
+        CopyValue(node.translation.value, trans);
+        aiMatrix4x4 t;
+        aiMatrix4x4::Translation(trans, t);
+        matrix = matrix * t;
+    }
+
+    if (node.rotation.isPresent) {
+        aiQuaternion rot;
+        CopyValue(node.rotation.value, rot);
+        matrix = matrix * aiMatrix4x4(rot.GetMatrix());
+    }
+
+    if (node.scale.isPresent) {
+        aiVector3D scal(1.f);
+        CopyValue(node.scale.value, scal);
+        aiMatrix4x4 s;
+        aiMatrix4x4::Scaling(scal, s);
+        matrix = matrix * s;
+    }
+}
+
+static void BuildVertexWeightMapping(Mesh::Primitive &primitive, std::vector<std::vector<aiVertexWeight>> &map) {
+    Mesh::Primitive::Attributes &attr = primitive.attributes;
+    if (attr.weight.empty() || attr.joint.empty()) {
+        return;
+    }
+    if (attr.weight[0]->count != attr.joint[0]->count) {
+        return;
+    }
+
+    size_t num_vertices = attr.weight[0]->count;
+
+    struct Weights {
+        float values[4];
+    };
+    Weights *weights = nullptr;
+    attr.weight[0]->ExtractData(weights);
+
+    struct Indices8 {
+        uint8_t values[4];
+    };
+    struct Indices16 {
+        uint16_t values[4];
+    };
+    Indices8 *indices8 = nullptr;
+    Indices16 *indices16 = nullptr;
+    if (attr.joint[0]->GetElementSize() == 4) {
+        attr.joint[0]->ExtractData(indices8);
+    } else {
+        attr.joint[0]->ExtractData(indices16);
+    }
+    //
+    if (nullptr == indices8 && nullptr == indices16) {
+        // Something went completely wrong!
+        ai_assert(false);
+        return;
+    }
+
+    for (size_t i = 0; i < num_vertices; ++i) {
+        for (int j = 0; j < 4; ++j) {
+            const unsigned int bone = (indices8 != nullptr) ? indices8[i].values[j] : indices16[i].values[j];
+            const float weight = weights[i].values[j];
+            if (weight > 0 && bone < map.size()) {
+                map[bone].reserve(8);
+                map[bone].emplace_back(static_cast<unsigned int>(i), weight);
+            }
+        }
+    }
+
+    delete[] weights;
+    delete[] indices8;
+    delete[] indices16;
+}
+
+static std::string GetNodeName(const Node &node) {
+    return node.name.empty() ? node.id : node.name;
+}
+
+void ParseExtensions(aiMetadata *metadata, const CustomExtension &extension) {
+    if (extension.mStringValue.isPresent) {
+        metadata->Add(extension.name, aiString(extension.mStringValue.value));
+    } else if (extension.mDoubleValue.isPresent) {
+        metadata->Add(extension.name, extension.mDoubleValue.value);
+    } else if (extension.mUint64Value.isPresent) {
+        metadata->Add(extension.name, extension.mUint64Value.value);
+    } else if (extension.mInt64Value.isPresent) {
+        metadata->Add(extension.name, static_cast<int32_t>(extension.mInt64Value.value));
+    } else if (extension.mBoolValue.isPresent) {
+        metadata->Add(extension.name, extension.mBoolValue.value);
+    } else if (extension.mValues.isPresent) {
+        aiMetadata val;
+        for (auto const & subExtension : extension.mValues.value) {
+            ParseExtensions(&val, subExtension);
+        }
+        metadata->Add(extension.name, val);
+    }
+}
+
+void ParseExtras(aiMetadata *metadata, const CustomExtension &extension) {
+    if (extension.mValues.isPresent) {
+        for (auto const & subExtension : extension.mValues.value) {
+            ParseExtensions(metadata, subExtension);
+        }
+    }
+}
+
+aiNode *ImportNode(aiScene *pScene, glTF2::Asset &r, std::vector<unsigned int> &meshOffsets, glTF2::Ref<glTF2::Node> &ptr) {
+    Node &node = *ptr;
+
+    aiNode *ainode = new aiNode(GetNodeName(node));
+
+    try {
+        if (!node.children.empty()) {
+            ainode->mNumChildren = unsigned(node.children.size());
+            ainode->mChildren = new aiNode *[ainode->mNumChildren];
+            std::fill(ainode->mChildren, ainode->mChildren + ainode->mNumChildren, nullptr);
+
+            for (unsigned int i = 0; i < ainode->mNumChildren; ++i) {
+                aiNode *child = ImportNode(pScene, r, meshOffsets, node.children[i]);
+                child->mParent = ainode;
+                ainode->mChildren[i] = child;
+            }
+        }
+
+        if (node.customExtensions || node.extras) {
+            ainode->mMetaData = new aiMetadata;
+            if (node.customExtensions) {
+                ParseExtensions(ainode->mMetaData, node.customExtensions);
+            }
+            if (node.extras) {
+                ParseExtras(ainode->mMetaData, node.extras);
+            }
+        }
+
+        GetNodeTransform(ainode->mTransformation, node);
+
+        if (!node.meshes.empty()) {
+            // GLTF files contain at most 1 mesh per node.
+            if (node.meshes.size() > 1)
+            {
+                throw DeadlyImportError("GLTF: Invalid input, found ", node.meshes.size(),
+                    " meshes in ", getContextForErrorMessages(node.id, node.name),
+                    ", but only 1 mesh per node allowed.");
+            }
+            int mesh_idx = node.meshes[0].GetIndex();
+            int count = meshOffsets[mesh_idx + 1] - meshOffsets[mesh_idx];
+
+            ainode->mNumMeshes = count;
+            ainode->mMeshes = new unsigned int[count];
+
+            if (node.skin) {
+                for (int primitiveNo = 0; primitiveNo < count; ++primitiveNo) {
+                    aiMesh *mesh = pScene->mMeshes[meshOffsets[mesh_idx] + primitiveNo];
+                    unsigned int numBones =static_cast<unsigned int>(node.skin->jointNames.size());
+
+                    std::vector<std::vector<aiVertexWeight>> weighting(numBones);
+                    BuildVertexWeightMapping(node.meshes[0]->primitives[primitiveNo], weighting);
+
+                    mesh->mNumBones = static_cast<unsigned int>(numBones);
+                    mesh->mBones = new aiBone *[mesh->mNumBones];
+                    std::fill(mesh->mBones, mesh->mBones + mesh->mNumBones, nullptr);
+
+                    // GLTF and Assimp choose to store bone weights differently.
+                    // GLTF has each vertex specify which bones influence the vertex.
+                    // Assimp has each bone specify which vertices it has influence over.
+                    // To convert this data, we first read over the vertex data and pull
+                    // out the bone-to-vertex mapping.  Then, when creating the aiBones,
+                    // we copy the bone-to-vertex mapping into the bone.  This is unfortunate
+                    // both because it's somewhat slow and because, for many applications,
+                    // we then need to reconvert the data back into the vertex-to-bone
+                    // mapping which makes things doubly-slow.
+
+                    mat4 *pbindMatrices = nullptr;
+                    node.skin->inverseBindMatrices->ExtractData(pbindMatrices);
+
+                    for (uint32_t i = 0; i < numBones; ++i) {
+                        const std::vector<aiVertexWeight> &weights = weighting[i];
+                        aiBone *bone = new aiBone();
+
+                        Ref<Node> joint = node.skin->jointNames[i];
+                        if (!joint->name.empty()) {
+                            bone->mName = joint->name;
+                        } else {
+                            // Assimp expects each bone to have a unique name.
+                            static const std::string kDefaultName = "bone_";
+                            char postfix[10] = { 0 };
+                            ASSIMP_itoa10(postfix, i);
+                            bone->mName = (kDefaultName + postfix);
+                        }
+                        GetNodeTransform(bone->mOffsetMatrix, *joint);
+                        CopyValue(pbindMatrices[i], bone->mOffsetMatrix);
+                        bone->mNumWeights = static_cast<uint32_t>(weights.size());
+
+                        if (bone->mNumWeights > 0) {
+                            bone->mWeights = new aiVertexWeight[bone->mNumWeights];
+                            memcpy(bone->mWeights, weights.data(), bone->mNumWeights * sizeof(aiVertexWeight));
+                        } else {
+                            // Assimp expects all bones to have at least 1 weight.
+                            bone->mWeights = new aiVertexWeight[1];
+                            bone->mNumWeights = 1;
+                            bone->mWeights->mVertexId = 0;
+                            bone->mWeights->mWeight = 0.f;
+                        }
+                        mesh->mBones[i] = bone;
+                    }
+
+                    if (pbindMatrices) {
+                        delete[] pbindMatrices;
+                    }
+                }
+            }
+
+            int k = 0;
+            for (unsigned int j = meshOffsets[mesh_idx]; j < meshOffsets[mesh_idx + 1]; ++j, ++k) {
+                ainode->mMeshes[k] = j;
+            }
+        }
+
+        if (node.camera) {
+            pScene->mCameras[node.camera.GetIndex()]->mName = ainode->mName;
+            if (node.translation.isPresent) {
+                aiVector3D trans;
+                CopyValue(node.translation.value, trans);
+                pScene->mCameras[node.camera.GetIndex()]->mPosition = trans;
+            }
+        }
+
+        if (node.light) {
+            pScene->mLights[node.light.GetIndex()]->mName = ainode->mName;
+
+            //range is optional - see https://github.com/KhronosGroup/glTF/tree/master/extensions/2.0/Khronos/KHR_lights_punctual
+            //it is added to meta data of parent node, because there is no other place to put it
+            if (node.light->range.isPresent) {
+                if (!ainode->mMetaData) {
+                    ainode->mMetaData = aiMetadata::Alloc(1);
+                    ainode->mMetaData->Set(0, "PBR_LightRange", node.light->range.value);
+                } else {
+                    ainode->mMetaData->Add("PBR_LightRange", node.light->range.value);
+                }
+            }
+        }
+
+        return ainode;
+    } catch (...) {
+        delete ainode;
+        throw;
+    }
+}
+
+void glTF2Importer::ImportNodes(glTF2::Asset &r) {
+    if (!r.scene) {
+        throw DeadlyImportError("GLTF: No scene");
+    }
+    ASSIMP_LOG_DEBUG("Importing nodes");
+
+    std::vector<Ref<Node>> rootNodes = r.scene->nodes;
+
+    // The root nodes
+    unsigned int numRootNodes = unsigned(rootNodes.size());
+    if (numRootNodes == 1) { // a single root node: use it
+        mScene->mRootNode = ImportNode(mScene, r, meshOffsets, rootNodes[0]);
+    } else if (numRootNodes > 1) { // more than one root node: create a fake root
+        aiNode *root = mScene->mRootNode = new aiNode("ROOT");
+
+        root->mChildren = new aiNode *[numRootNodes];
+        std::fill(root->mChildren, root->mChildren + numRootNodes, nullptr);
+
+        for (unsigned int i = 0; i < numRootNodes; ++i) {
+            aiNode *node = ImportNode(mScene, r, meshOffsets, rootNodes[i]);
+            node->mParent = root;
+            root->mChildren[root->mNumChildren++] = node;
+        }
+    } else {
+        mScene->mRootNode = new aiNode("ROOT");
+    }
+}
+
+struct AnimationSamplers {
+    AnimationSamplers() :
+            translation(nullptr),
+            rotation(nullptr),
+            scale(nullptr),
+            weight(nullptr) {
+        // empty
+    }
+
+    Animation::Sampler *translation;
+    Animation::Sampler *rotation;
+    Animation::Sampler *scale;
+    Animation::Sampler *weight;
+};
+
+aiNodeAnim *CreateNodeAnim(glTF2::Asset&, Node &node, AnimationSamplers &samplers) {
+    aiNodeAnim *anim = new aiNodeAnim();
+
+    try {
+        anim->mNodeName = GetNodeName(node);
+
+        static const float kMillisecondsFromSeconds = 1000.f;
+
+        if (samplers.translation && samplers.translation->input && samplers.translation->output) {
+            float *times = nullptr;
+            samplers.translation->input->ExtractData(times);
+            aiVector3D *values = nullptr;
+            samplers.translation->output->ExtractData(values);
+            anim->mNumPositionKeys = static_cast<uint32_t>(samplers.translation->input->count);
+            anim->mPositionKeys = new aiVectorKey[anim->mNumPositionKeys];
+            unsigned int ii = (samplers.translation->interpolation == Interpolation_CUBICSPLINE) ? 1 : 0;
+            for (unsigned int i = 0; i < anim->mNumPositionKeys; ++i) {
+                anim->mPositionKeys[i].mTime = times[i] * kMillisecondsFromSeconds;
+                anim->mPositionKeys[i].mValue = values[ii];
+                ii += (samplers.translation->interpolation == Interpolation_CUBICSPLINE) ? 3 : 1;
+            }
+            delete[] times;
+            delete[] values;
+        } else if (node.translation.isPresent) {
+            anim->mNumPositionKeys = 1;
+            anim->mPositionKeys = new aiVectorKey[anim->mNumPositionKeys];
+            anim->mPositionKeys->mTime = 0.f;
+            anim->mPositionKeys->mValue.x = node.translation.value[0];
+            anim->mPositionKeys->mValue.y = node.translation.value[1];
+            anim->mPositionKeys->mValue.z = node.translation.value[2];
+        }
+
+        if (samplers.rotation && samplers.rotation->input && samplers.rotation->output) {
+            float *times = nullptr;
+            samplers.rotation->input->ExtractData(times);
+            aiQuaternion *values = nullptr;
+            samplers.rotation->output->ExtractData(values);
+            anim->mNumRotationKeys = static_cast<uint32_t>(samplers.rotation->input->count);
+            anim->mRotationKeys = new aiQuatKey[anim->mNumRotationKeys];
+            unsigned int ii = (samplers.rotation->interpolation == Interpolation_CUBICSPLINE) ? 1 : 0;
+            for (unsigned int i = 0; i < anim->mNumRotationKeys; ++i) {
+                anim->mRotationKeys[i].mTime = times[i] * kMillisecondsFromSeconds;
+                anim->mRotationKeys[i].mValue.x = values[ii].w;
+                anim->mRotationKeys[i].mValue.y = values[ii].x;
+                anim->mRotationKeys[i].mValue.z = values[ii].y;
+                anim->mRotationKeys[i].mValue.w = values[ii].z;
+                ii += (samplers.rotation->interpolation == Interpolation_CUBICSPLINE) ? 3 : 1;
+            }
+            delete[] times;
+            delete[] values;
+        } else if (node.rotation.isPresent) {
+            anim->mNumRotationKeys = 1;
+            anim->mRotationKeys = new aiQuatKey[anim->mNumRotationKeys];
+            anim->mRotationKeys->mTime = 0.f;
+            anim->mRotationKeys->mValue.x = node.rotation.value[0];
+            anim->mRotationKeys->mValue.y = node.rotation.value[1];
+            anim->mRotationKeys->mValue.z = node.rotation.value[2];
+            anim->mRotationKeys->mValue.w = node.rotation.value[3];
+        }
+
+        if (samplers.scale && samplers.scale->input && samplers.scale->output) {
+            float *times = nullptr;
+            samplers.scale->input->ExtractData(times);
+            aiVector3D *values = nullptr;
+            samplers.scale->output->ExtractData(values);
+            anim->mNumScalingKeys = static_cast<uint32_t>(samplers.scale->input->count);
+            anim->mScalingKeys = new aiVectorKey[anim->mNumScalingKeys];
+            unsigned int ii = (samplers.scale->interpolation == Interpolation_CUBICSPLINE) ? 1 : 0;
+            for (unsigned int i = 0; i < anim->mNumScalingKeys; ++i) {
+                anim->mScalingKeys[i].mTime = times[i] * kMillisecondsFromSeconds;
+                anim->mScalingKeys[i].mValue = values[ii];
+                ii += (samplers.scale->interpolation == Interpolation_CUBICSPLINE) ? 3 : 1;
+            }
+            delete[] times;
+            delete[] values;
+        } else if (node.scale.isPresent) {
+            anim->mNumScalingKeys = 1;
+            anim->mScalingKeys = new aiVectorKey[anim->mNumScalingKeys];
+            anim->mScalingKeys->mTime = 0.f;
+            anim->mScalingKeys->mValue.x = node.scale.value[0];
+            anim->mScalingKeys->mValue.y = node.scale.value[1];
+            anim->mScalingKeys->mValue.z = node.scale.value[2];
+        }
+
+        return anim;
+    } catch (...) {
+        delete anim;
+        throw;
+    }
+}
+
+aiMeshMorphAnim *CreateMeshMorphAnim(glTF2::Asset&, Node &node, AnimationSamplers &samplers) {
+    auto *anim = new aiMeshMorphAnim();
+
+    try {
+        anim->mName = GetNodeName(node);
+
+        static const float kMillisecondsFromSeconds = 1000.f;
+
+        if (samplers.weight && samplers.weight->input && samplers.weight->output) {
+            float *times = nullptr;
+            samplers.weight->input->ExtractData(times);
+            float *values = nullptr;
+            samplers.weight->output->ExtractData(values);
+            anim->mNumKeys = static_cast<uint32_t>(samplers.weight->input->count);
+
+            // for Interpolation_CUBICSPLINE can have more outputs
+            const unsigned int weightStride = (unsigned int)samplers.weight->output->count / anim->mNumKeys;
+            const unsigned int numMorphs = (samplers.weight->interpolation == Interpolation_CUBICSPLINE) ? weightStride - 2 : weightStride;
+
+            anim->mKeys = new aiMeshMorphKey[anim->mNumKeys];
+            unsigned int ii = (samplers.weight->interpolation == Interpolation_CUBICSPLINE) ? 1 : 0;
+            for (unsigned int i = 0u; i < anim->mNumKeys; ++i) {
+                unsigned int k = weightStride * i + ii;
+                anim->mKeys[i].mTime = times[i] * kMillisecondsFromSeconds;
+                anim->mKeys[i].mNumValuesAndWeights = numMorphs;
+                anim->mKeys[i].mValues = new unsigned int[numMorphs];
+                anim->mKeys[i].mWeights = new double[numMorphs];
+
+                for (unsigned int j = 0u; j < numMorphs; ++j, ++k) {
+                    anim->mKeys[i].mValues[j] = j;
+                    anim->mKeys[i].mWeights[j] = (0.f > values[k]) ? 0.f : values[k];
+                }
+            }
+
+            delete[] times;
+            delete[] values;
+        }
+
+        return anim;
+    } catch (...) {
+        delete anim;
+        throw;
+    }
+}
+
+std::unordered_map<unsigned int, AnimationSamplers> GatherSamplers(Animation &anim) {
+    std::unordered_map<unsigned int, AnimationSamplers> samplers;
+    for (unsigned int c = 0; c < anim.channels.size(); ++c) {
+        Animation::Channel &channel = anim.channels[c];
+        if (channel.sampler < 0 || channel.sampler >= static_cast<int>(anim.samplers.size())) {
+            continue;
+        }
+
+        auto& animsampler = anim.samplers[channel.sampler];
+
+        if (!animsampler.input) {
+            ASSIMP_LOG_WARN("Animation ", anim.name, ": Missing sampler input. Skipping.");
+            continue;
+        }
+
+        if (!animsampler.output) {
+            ASSIMP_LOG_WARN("Animation ", anim.name, ": Missing sampler output. Skipping.");
+            continue;
+        }
+
+        if (animsampler.input->count > animsampler.output->count) {
+            ASSIMP_LOG_WARN("Animation ", anim.name, ": Number of keyframes in sampler input ", animsampler.input->count, " exceeds number of keyframes in sampler output ", animsampler.output->count);
+            continue;
+        }
+
+        const unsigned int node_index = channel.target.node.GetIndex();
+
+        AnimationSamplers &sampler = samplers[node_index];
+        if (channel.target.path == AnimationPath_TRANSLATION) {
+            sampler.translation = &anim.samplers[channel.sampler];
+        } else if (channel.target.path == AnimationPath_ROTATION) {
+            sampler.rotation = &anim.samplers[channel.sampler];
+        } else if (channel.target.path == AnimationPath_SCALE) {
+            sampler.scale = &anim.samplers[channel.sampler];
+        } else if (channel.target.path == AnimationPath_WEIGHTS) {
+            sampler.weight = &anim.samplers[channel.sampler];
+        }
+    }
+
+    return samplers;
+}
+
+void glTF2Importer::ImportAnimations(glTF2::Asset &r) {
+    if (!r.scene) return;
+
+    const unsigned numAnimations = r.animations.Size();
+    ASSIMP_LOG_DEBUG("Importing ", numAnimations, " animations");
+    mScene->mNumAnimations = numAnimations;
+    if (mScene->mNumAnimations == 0) {
+        return;
+    }
+
+    mScene->mAnimations = new aiAnimation *[numAnimations];
+    std::fill(mScene->mAnimations, mScene->mAnimations + numAnimations, nullptr);
+
+    for (unsigned int i = 0; i < numAnimations; ++i) {
+        aiAnimation *ai_anim = mScene->mAnimations[i] = new aiAnimation();
+
+        Animation &anim = r.animations[i];
+
+        ai_anim->mName = anim.name;
+        ai_anim->mDuration = 0;
+        ai_anim->mTicksPerSecond = 0;
+
+        std::unordered_map<unsigned int, AnimationSamplers> samplers = GatherSamplers(anim);
+
+        uint32_t numChannels = 0u;
+        uint32_t numMorphMeshChannels = 0u;
+
+        for (auto &iter : samplers) {
+            if ((nullptr != iter.second.rotation) || (nullptr != iter.second.scale) || (nullptr != iter.second.translation)) {
+                ++numChannels;
+            }
+            if (nullptr != iter.second.weight) {
+                ++numMorphMeshChannels;
+            }
+        }
+
+        ai_anim->mNumChannels = numChannels;
+        if (ai_anim->mNumChannels > 0) {
+            ai_anim->mChannels = new aiNodeAnim *[ai_anim->mNumChannels];
+            std::fill(ai_anim->mChannels, ai_anim->mChannels + ai_anim->mNumChannels, nullptr);
+            int j = 0;
+            for (auto &iter : samplers) {
+                if ((nullptr != iter.second.rotation) || (nullptr != iter.second.scale) || (nullptr != iter.second.translation)) {
+                    ai_anim->mChannels[j] = CreateNodeAnim(r, r.nodes[iter.first], iter.second);
+                    ++j;
+                }
+            }
+        }
+
+        ai_anim->mNumMorphMeshChannels = numMorphMeshChannels;
+        if (ai_anim->mNumMorphMeshChannels > 0) {
+            ai_anim->mMorphMeshChannels = new aiMeshMorphAnim *[ai_anim->mNumMorphMeshChannels];
+            std::fill(ai_anim->mMorphMeshChannels, ai_anim->mMorphMeshChannels + ai_anim->mNumMorphMeshChannels, nullptr);
+            int j = 0;
+            for (auto &iter : samplers) {
+                if (nullptr != iter.second.weight) {
+                    ai_anim->mMorphMeshChannels[j] = CreateMeshMorphAnim(r, r.nodes[iter.first], iter.second);
+                    ++j;
+                }
+            }
+        }
+
+        // Use the latest key-frame for the duration of the animation
+        double maxDuration = 0;
+        unsigned int maxNumberOfKeys = 0;
+        for (unsigned int j = 0; j < ai_anim->mNumChannels; ++j) {
+            auto chan = ai_anim->mChannels[j];
+            if (chan->mNumPositionKeys) {
+                auto lastPosKey = chan->mPositionKeys[chan->mNumPositionKeys - 1];
+                if (lastPosKey.mTime > maxDuration) {
+                    maxDuration = lastPosKey.mTime;
+                }
+                maxNumberOfKeys = std::max(maxNumberOfKeys, chan->mNumPositionKeys);
+            }
+            if (chan->mNumRotationKeys) {
+                auto lastRotKey = chan->mRotationKeys[chan->mNumRotationKeys - 1];
+                if (lastRotKey.mTime > maxDuration) {
+                    maxDuration = lastRotKey.mTime;
+                }
+                maxNumberOfKeys = std::max(maxNumberOfKeys, chan->mNumRotationKeys);
+            }
+            if (chan->mNumScalingKeys) {
+                auto lastScaleKey = chan->mScalingKeys[chan->mNumScalingKeys - 1];
+                if (lastScaleKey.mTime > maxDuration) {
+                    maxDuration = lastScaleKey.mTime;
+                }
+                maxNumberOfKeys = std::max(maxNumberOfKeys, chan->mNumScalingKeys);
+            }
+        }
+
+        for (unsigned int j = 0; j < ai_anim->mNumMorphMeshChannels; ++j) {
+            const auto *const chan = ai_anim->mMorphMeshChannels[j];
+
+            if (0u != chan->mNumKeys) {
+                const auto &lastKey = chan->mKeys[chan->mNumKeys - 1u];
+                if (lastKey.mTime > maxDuration) {
+                    maxDuration = lastKey.mTime;
+                }
+                maxNumberOfKeys = std::max(maxNumberOfKeys, chan->mNumKeys);
+            }
+        }
+
+        ai_anim->mDuration = maxDuration;
+        ai_anim->mTicksPerSecond = 1000.0;
+    }
+}
+
+static unsigned int countEmbeddedTextures(glTF2::Asset &r) {
+    unsigned int numEmbeddedTexs = 0;
+    for (size_t i = 0; i < r.images.Size(); ++i) {
+        if (r.images[i].HasData()) {
+            numEmbeddedTexs += 1;
+        }
+    }
+
+    return numEmbeddedTexs;
+}
+
+void glTF2Importer::ImportEmbeddedTextures(glTF2::Asset &r) {
+    mEmbeddedTexIdxs.resize(r.images.Size(), -1);
+    const unsigned int numEmbeddedTexs = countEmbeddedTextures(r);
+    if (numEmbeddedTexs == 0) {
+        return;
+    }
+
+    ASSIMP_LOG_DEBUG("Importing ", numEmbeddedTexs, " embedded textures");
+
+    mScene->mTextures = new aiTexture *[numEmbeddedTexs];
+    std::fill(mScene->mTextures, mScene->mTextures + numEmbeddedTexs, nullptr);
+
+    // Add the embedded textures
+    for (size_t i = 0; i < r.images.Size(); ++i) {
+        Image &img = r.images[i];
+        if (!img.HasData()) {
+            continue;
+        }
+
+        int idx = mScene->mNumTextures++;
+        mEmbeddedTexIdxs[i] = idx;
+
+        aiTexture *tex = mScene->mTextures[idx] = new aiTexture();
+
+        size_t length = img.GetDataLength();
+        void *data = img.StealData();
+
+        tex->mFilename = img.name;
+        tex->mWidth = static_cast<unsigned int>(length);
+        tex->mHeight = 0;
+        tex->pcData = reinterpret_cast<aiTexel *>(data);
+
+        if (!img.mimeType.empty()) {
+            const char *ext = strchr(img.mimeType.c_str(), '/') + 1;
+            if (ext) {
+                if (strcmp(ext, "jpeg") == 0) {
+                    ext = "jpg";
+                } else if(strcmp(ext, "ktx2") == 0) { //basisu: ktx remains
+                    ext = "kx2";
+                } else if(strcmp(ext, "basis") == 0) { //basisu
+                    ext = "bu";
+                }
+
+                size_t len = strlen(ext);
+                if (len <= 3) {
+                    strcpy(tex->achFormatHint, ext);
+                }
+            }
+        }
+    }
+}
+
+void glTF2Importer::ImportCommonMetadata(glTF2::Asset& a) {
+    ASSIMP_LOG_DEBUG("Importing metadata");
+    ai_assert(mScene->mMetaData == nullptr);
+    const bool hasVersion = !a.asset.version.empty();
+    const bool hasGenerator = !a.asset.generator.empty();
+    const bool hasCopyright = !a.asset.copyright.empty();
+    const bool hasSceneMetadata = a.scene->customExtensions;
+    if (hasVersion || hasGenerator || hasCopyright || hasSceneMetadata) {
+        mScene->mMetaData = new aiMetadata;
+        if (hasVersion) {
+            mScene->mMetaData->Add(AI_METADATA_SOURCE_FORMAT_VERSION, aiString(a.asset.version));
+        }
+        if (hasGenerator) {
+            mScene->mMetaData->Add(AI_METADATA_SOURCE_GENERATOR, aiString(a.asset.generator));
+        }
+        if (hasCopyright) {
+            mScene->mMetaData->Add(AI_METADATA_SOURCE_COPYRIGHT, aiString(a.asset.copyright));
+        }
+        if (hasSceneMetadata) {
+            ParseExtensions(mScene->mMetaData, a.scene->customExtensions);
+        }
+    }
+}
+
+void glTF2Importer::InternReadFile(const std::string &pFile, aiScene *pScene, IOSystem *pIOHandler) {
+    ASSIMP_LOG_DEBUG("Reading GLTF2 file");
+
+    // clean all member arrays
+    meshOffsets.clear();
+    mEmbeddedTexIdxs.clear();
+
+    this->mScene = pScene;
+
+    // read the asset file
+  	glTF2::Asset asset(pIOHandler, static_cast<rapidjson::IRemoteSchemaDocumentProvider*>(mSchemaDocumentProvider));
+    asset.Load(pFile, GetExtension(pFile) == "glb");
+    if (asset.scene) {
+        pScene->mName = asset.scene->name;
+    }
+
+    // Copy the data out
+    ImportEmbeddedTextures(asset);
+    ImportMaterials(asset);
+
+    ImportMeshes(asset);
+
+    ImportCameras(asset);
+    ImportLights(asset);
+
+    ImportNodes(asset);
+
+    ImportAnimations(asset);
+
+    ImportCommonMetadata(asset);
+
+    if (pScene->mNumMeshes == 0) {
+        pScene->mFlags |= AI_SCENE_FLAGS_INCOMPLETE;
+    }
+}
+
+void glTF2Importer::SetupProperties(const Importer *pImp) {
+    mSchemaDocumentProvider = static_cast<rapidjson::IRemoteSchemaDocumentProvider*>(pImp->GetPropertyPointer(AI_CONFIG_IMPORT_SCHEMA_DOCUMENT_PROVIDER));
+}
+
+#endif // ASSIMP_BUILD_NO_GLTF_IMPORTER