WaterFlush/Assets/AIPagedLod/Plugins/B3dmReader/WebGL/b3dmloader/b3dm_loader.cpp

#include <iostream>
#include <fstream>
#define TINYGLTF_IMPLEMENTATION
#define STB_IMAGE_IMPLEMENTATION
#define STB_IMAGE_WRITE_IMPLEMENTATION
#include "b3dm_loader.h"

MeshInfo* b3dm_loader::VisitorPrimitive(const tinygltf::Model& model, const Primitive& primitive)
{
	MeshInfo* meshInfo = new MeshInfo();
	//顶点索引
	const tinygltf::Accessor indexAccessor = model.accessors[primitive.indices];
	const tinygltf::BufferView& indexBufView = model.bufferViews[indexAccessor.bufferView];
	const tinygltf::Buffer& indexBuf = model.buffers[indexBufView.buffer];
	std::cout << indexAccessor.componentType << " " << indexAccessor.type << std::endl;
	int	faceCount = indexAccessor.count;
	unsigned int* faceIndex = new unsigned int[faceCount];
	memcpy(faceIndex, &indexBuf.data[0] + indexBufView.byteOffset + indexAccessor.byteOffset, faceCount * sizeof(unsigned int));
	/*meshInfo->mTriangles = new unsigned int[faceCount];
	for (int i = 0; i < faceCount; ++i)
	{
		meshInfo->mTriangles[i] = faceIndex[i];
	}*/
	meshInfo->mTriangles = faceIndex;
	meshInfo->mTriangleCount = faceCount;
	std::cout << "faceIndex count " << indexAccessor.count << std::endl;

	//顶点，uv	
	float* pointArr = NULL;
	float* textureArr = NULL;
	int pointCount = 0;
	int texCount = 0;

	std::map<std::string, int>::const_iterator it(primitive.attributes.begin());
	std::map<std::string, int>::const_iterator itEnd(primitive.attributes.end());
	for (; it != itEnd; it++)
	{
		const tinygltf::Accessor& accessor = model.accessors[it->second];
		const tinygltf::BufferView& bufferView_pt = model.bufferViews[accessor.bufferView];
		const tinygltf::Buffer& buffer_pt = model.buffers[bufferView_pt.buffer];

		int count = tinygltf::GetNumComponentsInType(accessor.type);
		if (it->first.compare("POSITION") == 0)
		{
			pointCount = accessor.count * count;
			pointArr = new float[pointCount];
			memcpy(pointArr, &buffer_pt.data[0] + bufferView_pt.byteOffset + accessor.byteOffset, pointCount * sizeof(float));
			meshInfo->mVertexCount = accessor.count;
			meshInfo->mVertexs = pointArr;
		}
		else if (it->first.compare("TEXCOORD_0") == 0) 
		{
			texCount = accessor.count * count;
			textureArr = new float[texCount];
			memcpy(textureArr, &buffer_pt.data[0] + bufferView_pt.byteOffset + accessor.byteOffset, texCount * sizeof(float));
			meshInfo->mTexCoordCount = accessor.count;
			meshInfo->mTexCoords = textureArr;
		}
	}

	//纹理数据

	tinygltf::Material mat = model.materials[primitive.material];
	int texIndex = mat.pbrMetallicRoughness.baseColorTexture.index;
	Texture texture = model.textures[texIndex];
	Image image = model.images[texture.source];
	std::cout << image.width << " " << image.height << " " << image.image.size() << " " << image.mimeType << std::endl;
	meshInfo->mImageResolutionS = image.width;
	meshInfo->mImageResolutionT = image.height;
	meshInfo->mImageSize = image.image.size();
	meshInfo->mImageData = new unsigned char[image.image.size()];
	memcpy(meshInfo->mImageData, &image.image[0], image.image.size());

	return meshInfo;
}

void b3dm_loader::VisitorModel(const tinygltf::Model& model)
{
	Scene curScene = model.scenes[0];
	for (int i = 0; i < (int)curScene.nodes.size(); ++i)
	{
		int nodeIndex = curScene.nodes[i];
		Node node = model.nodes[nodeIndex];
		int meshIndex = curScene.nodes[i];
		Mesh mesh = model.meshes[meshIndex];
		for (int j = 0; j < (int)mesh.primitives.size(); ++j)
		{		
			MeshInfo* meshInfo = VisitorPrimitive(model, mesh.primitives[j]);
			mMeshInfos.push_back(meshInfo);
		}
	}
}

int ReadB3dmHeaderLength(const std::string& filename)
{
	std::ifstream f(filename.c_str(), std::ios::binary);
	if (!f)
	{
		return 0;
	}
	f.seekg(0, f.beg);
	std::vector<char> file_data(28);
	f.read(&file_data.at(0), static_cast<std::streamsize>(28));
	if (file_data.empty())
		return 0;

	int header[7];
	::memcpy(header, file_data.data(), 7 * sizeof(int));
	int len_featureTable = header[3];

	return 7 * sizeof(int) + header[3] + header[4] + header[5] + header[6];
}

b3dm_loader* b3dm_loader::LoadB3dmFromFile(const std::string& filename)
{
	std::ifstream f(filename.c_str(), std::ios::binary);
	if (!f) 
	{
		std::cout << "Failed to open file: " << filename << std::endl;
		return nullptr;
	}

	f.seekg(0, f.end);
	size_t sz = static_cast<size_t>(f.tellg());
	int len_b3dm = ReadB3dmHeaderLength(filename);
	int gltfSize = sz - len_b3dm;
	std::vector<char> buf(gltfSize);
	f.seekg(len_b3dm, f.beg);
	f.read(&buf.at(0), static_cast<std::streamsize>(gltfSize));
	f.close();

	Model model;
	TinyGLTF loader;
	std::string err;
	std::string warn;
	std::string basedir;
	unsigned char* data = reinterpret_cast<unsigned char*>(&buf.at(0));
	int length = static_cast<unsigned int>(buf.size());
	bool ret = loader.LoadBinaryFromMemory(&model, &err, &warn, data, length, basedir);

	//loader.WriteGltfSceneToFile(&model, "./test.gltf");
	/*std::ofstream fout;
	fout.open("./test.glb", std::ios::app | std::ios::binary);
	fout.write(&buf.at(0), gltfSize);
	fout.close();*/

	if (!ret)
	{
		std::cout << "Failed to parse b3dm " << err << std::endl;
		return nullptr;
	}
	else
	{
		std::cout << "Success to parse b3dm " << sz << std::endl;
		b3dm_loader* loader = new b3dm_loader();
		loader->VisitorModel(model);
		return loader;
	}
}