Torque3D/Engine/lib/assimp/code/glTF2/glTF2Importer.cpp

/*
Open Asset Import Library (assimp)
----------------------------------------------------------------------

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All rights reserved.

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*/

#ifndef ASSIMP_BUILD_NO_GLTF_IMPORTER

#include "glTF2/glTF2Importer.h"
#include "PostProcessing/MakeVerboseFormat.h"
#include "glTF2/glTF2Asset.h"
#include "glTF2/glTF2AssetWriter.h"

#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 <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(),
		embeddedTexIdxs(),
		mScene(NULL) {
	// empty
}

glTF2Importer::~glTF2Importer() {
	// empty
}

const aiImporterDesc *glTF2Importer::GetInfo() const {
	return &desc;
}

bool glTF2Importer::CanRead(const std::string &pFile, IOSystem *pIOHandler, bool /* checkSig */) const {
	const std::string &extension = GetExtension(pFile);

	if (extension != "gltf" && extension != "glb") {
		return false;
	}

	if (pIOHandler) {
		glTF2::Asset asset(pIOHandler);
		asset.Load(pFile, extension == "glb");
		std::string version = asset.asset.version;
		return !version.empty() && version[0] == '2';
	}

	return false;
}

static 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;
	}
}

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);
}

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);
}

inline 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));
        mat->AddProperty(&prop.texCoord, 1, AI_MATKEY_GLTF_TEXTURE_TEXCOORD(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));
			}
		}
	}
}

inline void SetMaterialTextureProperty(std::vector<int> &embeddedTexIdxs, Asset &r, glTF2::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, glTF2::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();

	if (!mat.name.empty()) {
		aiString str(mat.name);

		aimat->AddProperty(&str, AI_MATKEY_NAME);
	}

	SetMaterialColorProperty(r, mat.pbrMetallicRoughness.baseColorFactor, aimat, AI_MATKEY_COLOR_DIFFUSE);
	SetMaterialColorProperty(r, mat.pbrMetallicRoughness.baseColorFactor, aimat, AI_MATKEY_GLTF_PBRMETALLICROUGHNESS_BASE_COLOR_FACTOR);

	SetMaterialTextureProperty(embeddedTexIdxs, r, mat.pbrMetallicRoughness.baseColorTexture, aimat, aiTextureType_DIFFUSE);
	SetMaterialTextureProperty(embeddedTexIdxs, r, mat.pbrMetallicRoughness.baseColorTexture, aimat, AI_MATKEY_GLTF_PBRMETALLICROUGHNESS_BASE_COLOR_TEXTURE);

	SetMaterialTextureProperty(embeddedTexIdxs, r, mat.pbrMetallicRoughness.metallicRoughnessTexture, aimat, AI_MATKEY_GLTF_PBRMETALLICROUGHNESS_METALLICROUGHNESS_TEXTURE);

	aimat->AddProperty(&mat.pbrMetallicRoughness.metallicFactor, 1, AI_MATKEY_GLTF_PBRMETALLICROUGHNESS_METALLIC_FACTOR);
	aimat->AddProperty(&mat.pbrMetallicRoughness.roughnessFactor, 1, AI_MATKEY_GLTF_PBRMETALLICROUGHNESS_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);

	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;

		aimat->AddProperty(&mat.pbrSpecularGlossiness.isPresent, 1, AI_MATKEY_GLTF_PBRSPECULARGLOSSINESS);
		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_GLTF_PBRSPECULARGLOSSINESS_GLOSSINESS_FACTOR);

		SetMaterialTextureProperty(embeddedTexIdxs, r, pbrSG.diffuseTexture, aimat, aiTextureType_DIFFUSE);

		SetMaterialTextureProperty(embeddedTexIdxs, r, pbrSG.specularGlossinessTexture, aimat, aiTextureType_SPECULAR);
	}
	if (mat.unlit) {
		aimat->AddProperty(&mat.unlit, 1, AI_MATKEY_GLTF_UNLIT);
	}

	return aimat;
}

void glTF2Importer::ImportMaterials(glTF2::Asset &r) {
	const unsigned int numImportedMaterials = unsigned(r.materials.Size());
	Material defaultMaterial;

	mScene->mNumMaterials = numImportedMaterials + 1;
	mScene->mMaterials = new aiMaterial *[mScene->mNumMaterials];
	mScene->mMaterials[numImportedMaterials] = ImportMaterial(embeddedTexIdxs, r, defaultMaterial);

	for (unsigned int i = 0; i < numImportedMaterials; ++i) {
		mScene->mMaterials[i] = ImportMaterial(embeddedTexIdxs, r, r.materials[i]);
	}
}

static inline void SetFace(aiFace &face, int a) {
	face.mNumIndices = 1;
	face.mIndices = new unsigned int[1];
	face.mIndices[0] = a;
}

static inline void SetFace(aiFace &face, int a, int b) {
	face.mNumIndices = 2;
	face.mIndices = new unsigned int[2];
	face.mIndices[0] = a;
	face.mIndices[1] = b;
}

static inline void SetFace(aiFace &face, int a, int b, int c) {
	face.mNumIndices = 3;
	face.mIndices = new unsigned int[3];
	face.mIndices[0] = a;
	face.mIndices[1] = b;
	face.mIndices[2] = c;
}

#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

void glTF2Importer::ImportMeshes(glTF2::Asset &r) {
	std::vector<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(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.size() > 0 && attr.position[0]) {
				aim->mNumVertices = static_cast<unsigned int>(attr.position[0]->count);
				attr.position[0]->ExtractData(aim->mVertices);
			}

			if (attr.normal.size() > 0 && attr.normal[0]) {
				attr.normal[0]->ExtractData(aim->mNormals);

				// only extract tangents if normals are present
				if (attr.tangent.size() > 0 && attr.tangent[0]) {
					// 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;
				}
				attr.color[c]->ExtractData(aim->mColors[c]);
			}
			for (size_t tc = 0; tc < attr.texcoord.size() && tc < AI_MAX_NUMBER_OF_TEXTURECOORDS; ++tc) {
				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.size() > 0) {
				aim->mNumAnimMeshes = (unsigned int)targets.size();
				aim->mAnimMeshes = new aiAnimMesh *[aim->mNumAnimMeshes];
				for (size_t i = 0; i < targets.size(); i++) {
					aim->mAnimMeshes[i] = aiCreateAnimMesh(aim);
					aiAnimMesh &aiAnimMesh = *(aim->mAnimMeshes[i]);
					Mesh::Primitive::Target &target = targets[i];

					if (target.position.size() > 0) {
						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 (target.normal.size() > 0) {
						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 (target.tangent.size() > 0) {
						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];
					}
				}
			}

			aiFace *faces = nullptr;
			size_t nFaces = 0;

			if (prim.indices) {
				size_t count = prim.indices->count;

				Accessor::Indexer data = prim.indices->GetIndexer();
				ai_assert(data.IsValid());

				switch (prim.mode) {
					case PrimitiveMode_POINTS: {
						nFaces = count;
						faces = new aiFace[nFaces];
						for (unsigned int i = 0; i < count; ++i) {
							SetFace(faces[i], 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;
						}
						faces = new aiFace[nFaces];
						for (unsigned int i = 0; i < count; i += 2) {
							SetFace(faces[i / 2], 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);
						faces = new aiFace[nFaces];
						SetFace(faces[0], data.GetUInt(0), data.GetUInt(1));
						for (unsigned int i = 2; i < count; ++i) {
							SetFace(faces[i - 1], faces[i - 2].mIndices[1], data.GetUInt(i));
						}
						if (prim.mode == PrimitiveMode_LINE_LOOP) { // close the loop
							SetFace(faces[count - 1], faces[count - 2].mIndices[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;
						}
						faces = new aiFace[nFaces];
						for (unsigned int i = 0; i < count; i += 3) {
							SetFace(faces[i / 3], data.GetUInt(i), data.GetUInt(i + 1), data.GetUInt(i + 2));
						}
						break;
					}
					case PrimitiveMode_TRIANGLE_STRIP: {
						nFaces = count - 2;
						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
								SetFace(faces[i], 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
								SetFace(faces[i], data.GetUInt(i), data.GetUInt(i + 1), data.GetUInt(i + 2));
							}
						}
						break;
					}
					case PrimitiveMode_TRIANGLE_FAN:
						nFaces = count - 2;
						faces = new aiFace[nFaces];
						SetFace(faces[0], data.GetUInt(0), data.GetUInt(1), data.GetUInt(2));
						for (unsigned int i = 1; i < nFaces; ++i) {
							SetFace(faces[i], faces[0].mIndices[0], faces[i - 1].mIndices[2], 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;
						faces = new aiFace[nFaces];
						for (unsigned int i = 0; i < count; ++i) {
							SetFace(faces[i], 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;
						}
						faces = new aiFace[nFaces];
						for (unsigned int i = 0; i < count; i += 2) {
							SetFace(faces[i / 2], i, i + 1);
						}
						break;
					}

					case PrimitiveMode_LINE_LOOP:
					case PrimitiveMode_LINE_STRIP: {
						nFaces = count - ((prim.mode == PrimitiveMode_LINE_STRIP) ? 1 : 0);
						faces = new aiFace[nFaces];
						SetFace(faces[0], 0, 1);
						for (unsigned int i = 2; i < count; ++i) {
							SetFace(faces[i - 1], faces[i - 2].mIndices[1], i);
						}
						if (prim.mode == PrimitiveMode_LINE_LOOP) { // close the loop
							SetFace(faces[count - 1], faces[count - 2].mIndices[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 = (unsigned int)nFaces * 3;
						}
						faces = new aiFace[nFaces];
						for (unsigned int i = 0; i < count; i += 3) {
							SetFace(faces[i / 3], i, i + 1, i + 2);
						}
						break;
					}
					case PrimitiveMode_TRIANGLE_STRIP: {
						nFaces = count - 2;
						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
								SetFace(faces[i], i + 1, i, i + 2);
							} else {
								//For odd n, vertices n, n+1, and n+2 define triangle n
								SetFace(faces[i], i, i + 1, i + 2);
							}
						}
						break;
					}
					case PrimitiveMode_TRIANGLE_FAN:
						nFaces = count - 2;
						faces = new aiFace[nFaces];
						SetFace(faces[0], 0, 1, 2);
						for (unsigned int i = 1; i < nFaces; ++i) {
							SetFace(faces[i], faces[0].mIndices[0], faces[i - 1].mIndices[2], i + 2);
						}
						break;
				}
			}

			if (nullptr != faces) {
				aim->mFaces = faces;
				aim->mNumFaces = static_cast<unsigned int>(nFaces);
				ai_assert(CheckValidFacesIndices(faces, static_cast<unsigned>(nFaces), 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;

	mScene->mNumCameras = r.cameras.Size();
	mScene->mCameras = new aiCamera *[r.cameras.Size()];

	for (size_t i = 0; i < r.cameras.Size(); ++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->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;

	mScene->mNumLights = r.lights.Size();
	mScene->mLights = new aiLight *[r.lights.Size()];

	for (size_t i = 0; i < r.lights.Size(); ++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);
	} else {
		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;
}

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));

	if (!node.children.empty()) {
		ainode->mNumChildren = unsigned(node.children.size());
		ainode->mChildren = new aiNode *[ainode->mNumChildren];

		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;
		}
	}

	GetNodeTransform(ainode->mTransformation, node);

	if (!node.meshes.empty()) {
		// GLTF files contain at most 1 mesh per node.
		assert(node.meshes.size() == 1);
		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);

				unsigned int realNumBones = 0;
				for (uint32_t i = 0; i < numBones; ++i) {
					if (weighting[i].size() > 0) {
						realNumBones++;
					}
				}

				mesh->mNumBones = static_cast<unsigned int>(realNumBones);
				mesh->mBones = new aiBone *[mesh->mNumBones];

				// 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);

				int cb = 0;
				for (uint32_t i = 0; i < numBones; ++i) {
					const std::vector<aiVertexWeight> &weights = weighting[i];
					if (weights.size() > 0) {
						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());
						bone->mWeights = new aiVertexWeight[bone->mNumWeights];
						memcpy(bone->mWeights, weights.data(), bone->mNumWeights * sizeof(aiVertexWeight));
						mesh->mBones[cb++] = 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) {
			ainode->mMetaData = aiMetadata::Alloc(1);
			ainode->mMetaData->Set(0, "PBR_LightRange", node.light->range.value);
		}
	}

	return ainode;
}

void glTF2Importer::ImportNodes(glTF2::Asset &r) {
	if (!r.scene) {
        return;
    }

	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 = new aiNode("ROOT");
		root->mChildren = new aiNode *[numRootNodes];
		for (unsigned int i = 0; i < numRootNodes; ++i) {
			aiNode *node = ImportNode(mScene, r, meshOffsets, rootNodes[i]);
			node->mParent = root;
			root->mChildren[root->mNumChildren++] = node;
		}
		mScene->mRootNode = 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 &r, Node &node, AnimationSamplers &samplers) {
	aiNodeAnim *anim = new aiNodeAnim();
	anim->mNodeName = GetNodeName(node);

	static const float kMillisecondsFromSeconds = 1000.f;

	if (samplers.translation) {
		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];
		for (unsigned int i = 0; i < anim->mNumPositionKeys; ++i) {
			anim->mPositionKeys[i].mTime = times[i] * kMillisecondsFromSeconds;
			anim->mPositionKeys[i].mValue = values[i];
		}
		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) {
		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];
		for (unsigned int i = 0; i < anim->mNumRotationKeys; ++i) {
			anim->mRotationKeys[i].mTime = times[i] * kMillisecondsFromSeconds;
			anim->mRotationKeys[i].mValue.x = values[i].w;
			anim->mRotationKeys[i].mValue.y = values[i].x;
			anim->mRotationKeys[i].mValue.z = values[i].y;
			anim->mRotationKeys[i].mValue.w = values[i].z;
		}
		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) {
		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];
		for (unsigned int i = 0; i < anim->mNumScalingKeys; ++i) {
			anim->mScalingKeys[i].mTime = times[i] * kMillisecondsFromSeconds;
			anim->mScalingKeys[i].mValue = values[i];
		}
		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;
}

aiMeshMorphAnim *CreateMeshMorphAnim(glTF2::Asset &r, Node &node, AnimationSamplers &samplers) {
	aiMeshMorphAnim *anim = new aiMeshMorphAnim();
	anim->mName = GetNodeName(node);

	static const float kMillisecondsFromSeconds = 1000.f;

	if (nullptr != samplers.weight) {
		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);

		const unsigned int numMorphs = (unsigned int)samplers.weight->output->count / anim->mNumKeys;

		anim->mKeys = new aiMeshMorphKey[anim->mNumKeys];
		unsigned int k = 0u;
		for (unsigned int i = 0u; i < anim->mNumKeys; ++i) {
			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;
}

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 >= static_cast<int>(anim.samplers.size())) {
			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;

	mScene->mNumAnimations = r.animations.Size();
	if (mScene->mNumAnimations == 0) {
		return;
	}

	mScene->mAnimations = new aiAnimation *[mScene->mNumAnimations];
	for (unsigned int i = 0; i < r.animations.Size(); ++i) {
		Animation &anim = r.animations[i];

		aiAnimation *ai_anim = new aiAnimation();
		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];
			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];
			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 keyframe 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;

		mScene->mAnimations[i] = ai_anim;
	}
}

void glTF2Importer::ImportEmbeddedTextures(glTF2::Asset &r) {
	embeddedTexIdxs.resize(r.images.Size(), -1);

	int numEmbeddedTexs = 0;
	for (size_t i = 0; i < r.images.Size(); ++i) {
		if (r.images[i].HasData()) {
			numEmbeddedTexs += 1;
		}
	}

	if (numEmbeddedTexs == 0)
		return;

	mScene->mTextures = new aiTexture *[numEmbeddedTexs];

	// 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++;
		embeddedTexIdxs[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";
                }

				size_t len = strlen(ext);
				if (len <= 3) {
					strcpy(tex->achFormatHint, ext);
				}
			}
		}
	}
}

void glTF2Importer::ImportCommonMetadata(glTF2::Asset& a) {
    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();
    if (hasVersion || hasGenerator || hasCopyright) {
        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));
        }
    }
}

void glTF2Importer::InternReadFile(const std::string &pFile, aiScene *pScene, IOSystem *pIOHandler) {
	// clean all member arrays
	meshOffsets.clear();
	embeddedTexIdxs.clear();

	this->mScene = pScene;

	// read the asset file
	glTF2::Asset asset(pIOHandler);
	asset.Load(pFile, GetExtension(pFile) == "glb");

	//
	// 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;
	}
}

#endif // ASSIMP_BUILD_NO_GLTF_IMPORTER