gltf cpp

main.cpp

#include <iostream>
#include <fstream>


#include <GL/glew.h>
#include <GLFW/glfw3.h>
#include <glm/gtc/matrix_transform.hpp>

#include "window.h"
#include "shaders.h"

#define TINYGLTF_IMPLEMENTATION
#define STB_IMAGE_IMPLEMENTATION
#define STB_IMAGE_WRITE_IMPLEMENTATION
#define TINYGLTF_NOEXCEPTION
#define JSON_NOEXCEPTION
#include "tiny_gltf.h"

#define BUFFER_OFFSET(i) ((char *)NULL + (i))
GLuint gVao;
std::map<std::string, GLint> gAttribs;

bool loadModel(tinygltf::Model &model)
{
	tinygltf::TinyGLTF loader;
	std::string err;
	std::string warn;
	const char* filename = "cube/cube.gltf";

	bool res = loader.LoadASCIIFromFile(&model, &err, &warn, filename);
	if (!warn.empty()) {
		printf("Warn: %s\n", warn.c_str());
	}

	if (!err.empty()) {
		printf("Err: %s\n", err.c_str());
	}

	if (!res)
		printf("Failed to parse glTF\n");
	else std::cout << "loaded gltf " << filename << std::endl;

	return res;
}


std::map<int, GLuint> bindMesh(std::map<int, GLuint> vbos, tinygltf::Model &model, tinygltf::Mesh &mesh)
{
	glGenVertexArrays(1, &gVao);
	glBindVertexArray(gVao);

	for (size_t i = 0; i < model.bufferViews.size(); ++i) {
		const tinygltf::BufferView &bufferView = model.bufferViews[i];
		if (bufferView.target == 0) { // TODO impl drawarrays
			std::cout << "WARN: bufferView.target is zero" << std::endl;
			continue;  // Unsupported bufferView.
		}

		tinygltf::Buffer buffer = model.buffers[bufferView.buffer];
		std::cout << "bufferview.target " << bufferView.target << std::endl;

		GLuint vbo;
		glGenBuffers(1, &vbo);
		glBindBuffer(bufferView.target, vbo);

		std::cout << "buffer.data.size = " << buffer.data.size() << ", bufferview.byteOffset = " 
			<< bufferView.byteOffset << std::endl;

		glBufferData(bufferView.target, bufferView.byteLength, 
			&buffer.data.at(0) + bufferView.byteOffset, GL_STATIC_DRAW);
		
		for (size_t i = 0; i < mesh.primitives.size(); ++i)
		{
			tinygltf::Primitive primitive = mesh.primitives[i];
			tinygltf::Accessor indexAccessor = model.accessors[primitive.indices];

			for (auto& attrib : primitive.attributes)
			{
				tinygltf::Accessor accessor = model.accessors[attrib.second];

				int byteStride = accessor.ByteStride(model.bufferViews[accessor.bufferView]);


				int size = 1;
				if (accessor.type != TINYGLTF_TYPE_SCALAR) {
					size = accessor.type;
				}

				int vaa = -1;
				if (attrib.first.compare("POSITION") == 0) vaa = 0;
				if (attrib.first.compare("NORMAL") == 0) vaa = 1;
				if (attrib.first.compare("TEXCOORD_0") == 0) vaa = 2;
				if (vaa > -1)
				{
					glEnableVertexAttribArray(vaa);
					glVertexAttribPointer(
						vaa,
						size,
						accessor.componentType,
						accessor.normalized ? GL_TRUE : GL_FALSE,
						byteStride,
						BUFFER_OFFSET(accessor.byteOffset)
					);
				}
				else std::cout << "vaa missing: " << attrib.first << std::endl;
			}
		}

		vbos[i] = vbo;
	}

	glBindVertexArray(0);

	return vbos;
}

// bind models
void bindModelNodes(std::map<int, GLuint> vbos, tinygltf::Model &model, tinygltf::Node &node)
{
	bindMesh(vbos, model, model.meshes[node.mesh]);
	for (size_t i = 0; i < node.children.size(); i++) {
		bindModelNodes(vbos, model, model.nodes[node.children[i]]);
	}
}
void bindModel(std::map<int, GLuint> vbos, tinygltf::Model &model)
{
	const tinygltf::Scene &scene = model.scenes[model.defaultScene];
	for (size_t i = 0; i < scene.nodes.size(); ++i) {
		bindModelNodes(vbos, model, model.nodes[scene.nodes[i]]);
	}
}



void drawMesh(std::map<int, GLuint> vbos, tinygltf::Model &model, tinygltf::Mesh &mesh)
{
	glBindVertexArray(gVao);
	for (size_t i = 0; i < mesh.primitives.size(); ++i)
	{
		tinygltf::Primitive primitive = mesh.primitives[i];
		tinygltf::Accessor indexAccessor = model.accessors[primitive.indices];
		glDrawElements(primitive.mode, indexAccessor.count, indexAccessor.componentType,
			BUFFER_OFFSET(indexAccessor.byteOffset));
	}
}

// recursively draw node and children nodes of model
void drawModelNodes(std::map<int, GLuint> vbos, tinygltf::Model &model, tinygltf::Node &node)
{
	drawMesh(vbos, model, model.meshes[node.mesh]);
	for (size_t i = 0; i < node.children.size(); i++) {
		drawModelNodes(vbos, model, model.nodes[node.children[i]]);
	}
}
void drawModel(std::map<int, GLuint> vbos, tinygltf::Model &model)
{
	const tinygltf::Scene &scene = model.scenes[model.defaultScene];
	for (size_t i = 0; i < scene.nodes.size(); ++i) {
		drawModelNodes(vbos, model, model.nodes[scene.nodes[i]]);
	}
}




void dbgMesh(tinygltf::Model &model)
{
	tinygltf::Primitive primitive = model.meshes[0].primitives[0];
	const tinygltf::Accessor &indexAccessor = model.accessors[primitive.indices];

	std::cout << "indexaccessor: count " << indexAccessor.count << ", type " << 
		indexAccessor.componentType << std::endl;

	std::cout << "material : " << primitive.material << std::endl;
	std::cout << "indices : " << primitive.indices << std::endl;
	std::cout << "mode     : " << "(" << primitive.mode << ")" << std::endl;
	std::cout << "attributes(items=" << primitive.attributes.size() << ")" << std::endl;
}


glm::mat4 genMVP(glm::mat4 model_mat, float fov, int w, int h)
{
	glm::mat4 Projection = glm::perspective(glm::radians(fov), (float)w / (float)h, 0.01f, 1000.0f);

	// Or, for an ortho camera :
	//glm::mat4 Projection = glm::ortho(-10.0f,10.0f,-10.0f,10.0f,0.0f,100.0f); // In world coordinates

	// Camera matrix
	glm::mat4 View = glm::lookAt(
		glm::vec3(5, 5, -10), // Camera in World Space
		glm::vec3(0, 0, 0), // and looks at the origin
		glm::vec3(0, 1, 0)  // Head is up (set to 0,-1,0 to look upside-down)
	);

	glm::mat4 mvp = Projection * View * model_mat;

	return mvp;
}

void displayLoop(Window& window)
{
	Shaders shader = Shaders();

	tinygltf::Model model;
	if (!loadModel(model)) return;

	std::map<int, GLuint> vbos;
	bindModel(vbos, model);

	//dbgMesh(model);

	// Model matrix : an identity matrix (model will be at the origin)
	glm::mat4 model_mat = glm::mat4(1.0f);

	while (!window.Close())
	{
		window.Resize();

		glClearColor(0.2, 0.2, 0.2, 1.0);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

		glUseProgram(shader.pid);
		//glEnableVertexAttribArray(0);

		GLuint MVP_u = glGetUniformLocation(shader.pid, "MVP");

		GLint w, h;
		glfwGetWindowSize(window.window, &w, &h);
		glm::mat4 mvp = genMVP(model_mat, 45.0f, w, h);
		glUniformMatrix4fv(MVP_u, 1, GL_FALSE, &mvp[0][0]);

		GLuint MVI_u = glGetUniformLocation(shader.pid, "MVI");
		glm::mat3 mvi = glm::transpose(glm::inverse(glm::mat3(model_mat)));
		glUniformMatrix4fv(MVI_u, 1, GL_FALSE, &mvi[0][0]);
		
		drawModel(vbos, model);
		glfwSwapBuffers(window.window);
		glfwPollEvents();
	}

	// cleanup vbos
	for (size_t i = 0; i < vbos.size(); ++i)
	{
		glDeleteBuffers(1, &vbos[i]);
	}
}


int main(int argc, char **argv)
{
	if (!glfwInit()) return -1;
	Window window = Window(800, 600, "Chirp");
	glfwMakeContextCurrent(window.window);

	glewInit();
	std::cout << glGetString(GL_RENDERER) << '\n';
	std::cout << glGetString(GL_VERSION) << '\n';

	glEnable(GL_DEPTH_TEST);
	glDepthFunc(GL_LESS);
	displayLoop(window);

	glfwTerminate();
	return 0;
}

shaders.cpp

#include "shaders.h"
#include <iostream>
#include <vector>


#include <GL/glew.h>
#include <GLFW/glfw3.h>

std::string FragmentShaderCode =
"#version 330 core\n\
in vec3 in_normal;\n\
in vec2 in_texcoord;\n\
uniform mat3 MVI; \n\
\n\
out vec4 color;\n\
void main() {\n\
	color = vec4(0.5 * normalize(in_normal) + 0.5, 1.0);\n\
}\n\
";

std::string VertexShaderCode =
"#version 330 core\n\
layout(location = 0) in vec3 in_vertex;\n\
layout(location = 1) in vec3 in_normal;\n\
layout(location = 2) in vec2 in_texcoord;\n\
\n\
uniform mat4 MVP;\n\
uniform mat3 MVI;\n\
\n\
out vec3 normal;\n\
out vec2 texcoord;\n\
\n\
void main(){\n\
	// Output position of the vertex, in clip space : MVP * position\n\
	gl_Position = MVP * vec4(in_vertex, 1);\n\
\n\
	normal = MVI * vec4(normalize(in_normal), 0).xyz;\n\
\n\
	texcoord = in_texcoord;\n\
}";


Shaders::Shaders()
{

	// Create the shaders
	GLuint VertexShaderID = glCreateShader(GL_VERTEX_SHADER);
	GLuint FragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);


	GLint Result = GL_FALSE;
	int InfoLogLength;

	// Compile Vertex Shader
	char const * VertexSourcePointer = VertexShaderCode.c_str();
	glShaderSource(VertexShaderID, 1, &VertexSourcePointer, NULL);
	glCompileShader(VertexShaderID);

	// Check Vertex Shader
	glGetShaderiv(VertexShaderID, GL_COMPILE_STATUS, &Result);
	glGetShaderiv(VertexShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
	if (InfoLogLength > 0) {
		std::vector<char> VertexShaderErrorMessage(InfoLogLength + 1);
		glGetShaderInfoLog(VertexShaderID, InfoLogLength, NULL, &VertexShaderErrorMessage[0]);
		printf("%s\n", &VertexShaderErrorMessage[0]);
	}

	// Compile Fragment Shader
	char const * FragmentSourcePointer = FragmentShaderCode.c_str();
	glShaderSource(FragmentShaderID, 1, &FragmentSourcePointer, NULL);
	glCompileShader(FragmentShaderID);

	// Check Fragment Shader
	glGetShaderiv(FragmentShaderID, GL_COMPILE_STATUS, &Result);
	glGetShaderiv(FragmentShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
	if (InfoLogLength > 0) {
		std::vector<char> FragmentShaderErrorMessage(InfoLogLength + 1);
		glGetShaderInfoLog(FragmentShaderID, InfoLogLength, NULL, &FragmentShaderErrorMessage[0]);
		printf("%s\n", &FragmentShaderErrorMessage[0]);
	}

	// Link the program
	printf("Linking program\n");
	GLuint ProgramID = glCreateProgram();
	glAttachShader(ProgramID, VertexShaderID);
	glAttachShader(ProgramID, FragmentShaderID);
	glLinkProgram(ProgramID);

	// Check the program
	glGetProgramiv(ProgramID, GL_LINK_STATUS, &Result);
	glGetProgramiv(ProgramID, GL_INFO_LOG_LENGTH, &InfoLogLength);
	if (InfoLogLength > 0) {
		std::vector<char> ProgramErrorMessage(InfoLogLength + 1);
		glGetProgramInfoLog(ProgramID, InfoLogLength, NULL, &ProgramErrorMessage[0]);
		printf("%s\n", &ProgramErrorMessage[0]);
	}

	glDetachShader(ProgramID, VertexShaderID);
	glDetachShader(ProgramID, FragmentShaderID);

	glDeleteShader(VertexShaderID);
	glDeleteShader(FragmentShaderID);

	this->pid = ProgramID;
}


Shaders::~Shaders()
{
}

work in progress, basic gltf rendering using glfw on Windows