Model.cpp

#include <stb_image.h>

#include "Model.h"


Model::Model(const char* path) {
	loadModel(path);
}

void Model::Draw(Shader &shader) {
	for (unsigned int i = 0; i < meshes.size(); i++) {
		meshes[i].Draw(shader);	
	}
}

void Model::loadModel(std::string path) {
	Assimp::Importer importer;
	const aiScene* scene = importer.ReadFile(path, aiProcess_Triangulate | aiProcess_FlipUVs);

	if (!scene || scene->mFlags & AI_SCENE_FLAGS_INCOMPLETE || !scene->mRootNode) {
		// TODO: Add proper logging utility
		std::cerr << "ERROR Assimp " << importer.GetErrorString() << std::endl;
		return;
	}

	directory = path.substr(0, path.find_last_of('/'));

	processNode(scene->mRootNode, scene);
}

void Model::processNode(aiNode* node, const aiScene* scene) {
	// Process all of the node's meshes
	for (unsigned int i = 0; i < node->mNumMeshes; i++) {
		aiMesh* mesh = scene->mMeshes[node->mMeshes[i]];
		meshes.push_back(processMesh(mesh, scene));
	}

	// Process all of the node's children's meshes
	for (unsigned int i = 0; i < node->mNumChildren; i++) {
		processNode(node->mChildren[i], scene);
	}
}

Mesh Model::processMesh(aiMesh* mesh, const aiScene* scene) {
	std::vector<Vertex> vertices;
	std::vector<unsigned int> indices;
	std::vector<Texture> textures;

	// Vertices
	for (unsigned int i = 0; i < mesh->mNumVertices; i++) {
		Vertex vertex;
		glm::vec3 vector;

		// Vertex positions
		vector.x = mesh->mVertices[i].x;
		vector.y = mesh->mVertices[i].y;
		vector.z = mesh->mVertices[i].z;
		vertex.Position = vector;

		if (vector.x < minVertexPos.x) {
			minVertexPos.x = vector.x;
		}

		if (vector.y < minVertexPos.y) {
			minVertexPos.y = vector.y;
		}

		if (vector.z < minVertexPos.z) {
			minVertexPos.z = vector.z;
		}

		if (vector.x > maxVertexPos.x) {
			maxVertexPos.x = vector.x;
		}

		if (vector.y > maxVertexPos.y) {
			maxVertexPos.y = vector.y;
		}

		if (vector.x > maxVertexPos.z) {
			maxVertexPos.z = vector.z;
		}

		// Vertex normals
		if (mesh->HasNormals()) {
			vector.x = mesh->mNormals[i].x;
			vector.y = mesh->mNormals[i].y;
			vector.z = mesh->mNormals[i].z;
		}

		// Texture coordinates
		if (mesh->mTextureCoords[0]) {
			glm::vec2 vec;

			vec.x = mesh->mTextureCoords[0][i].x;
			vec.y = mesh->mTextureCoords[0][i].y;
			vertex.TexCoords = vec;
		}
		else {
			vertex.TexCoords = glm::vec2(0.0f, 0.0f);
		}

		vertices.push_back(vertex);
	}


	// Indices
	for (unsigned int i = 0; i < mesh->mNumFaces; i++) {
		aiFace face = mesh->mFaces[i];
		for (unsigned int j = 0; j < face.mNumIndices; j++) {
			indices.push_back(face.mIndices[j]);
		}
	}

	// Materials
	if (mesh->mMaterialIndex >= 0) {
		aiMaterial* material = scene->mMaterials[mesh->mMaterialIndex];
		std::vector<Texture> diffuseMaps = loadMaterialTextures(material, aiTextureType_DIFFUSE, "textureDiffuse");
		textures.insert(textures.end(), diffuseMaps.begin(), diffuseMaps.end());
		std::vector<Texture> specularMaps = loadMaterialTextures(material, aiTextureType_SPECULAR, "textureSpecular");
		textures.insert(textures.end(), specularMaps.begin(), specularMaps.end());
	}

	return Mesh(vertices, indices, textures);
}

std::vector<Texture> Model::loadMaterialTextures(aiMaterial* mat, aiTextureType type, std::string typeName) {
	std::vector<Texture> textures;

	for (unsigned int i = 0; i < mat->GetTextureCount(type); i++) {
		aiString str;
		mat->GetTexture(type, i, &str);
		bool skip = false;
		for (unsigned int j = 0; j < loadedTextures.size(); j++) {
			if (std::strcmp(loadedTextures[j].path.data(), str.C_Str()) == 0) {
				textures.push_back(loadedTextures[j]);
				skip = true;
				break;
			}
		}
		if (!skip) {
			Texture texture;
			texture.id = TextureFromFile(str.C_Str(), directory);
			texture.type = typeName;
			texture.path = str.C_Str();
			textures.push_back(texture);
			loadedTextures.push_back(texture);
		}

	}

	return textures;
}

std::vector<Mesh> Model::getMeshes() const {
	return meshes;
}

unsigned int TextureFromFile(const char* path, const std::string& directory) {
	std::string filename = std::string(path);
	filename = directory + "/" + filename;
	// std::cout << "Filename: " << filename << std::endl;

	unsigned int id;
	glGenTextures(1, &id);
	
	int width, height, numChannels;
	unsigned char* data = stbi_load(filename.c_str(), &width, &height, &numChannels, 0);

	if (data) {
		GLenum format = GL_RGB;
		if (numChannels == 1) {
			format = GL_RED;
		}
		else if (numChannels == 3) {
			format = GL_RGB;
		}
		else if (numChannels == 4) {
			format = GL_RGBA;
		}

		glBindTexture(GL_TEXTURE_2D, id);
		glTexImage2D(GL_TEXTURE_2D, 0, format, width, height, 0, format, GL_UNSIGNED_BYTE, data);
		glGenerateMipmap(GL_TEXTURE_2D);

		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

		stbi_image_free(data);
	}
	else {
		// TODO: Add proper logging utility
		std::cerr << "ERROR Texture failed to load at path: " << path << std::endl;
		stbi_image_free(data);
	}

	return id;
}