added a model class

include/myEngine/model.hpp

@@ -0,0 +1,246 @@
+#ifndef MODEL_H
+#define MODEL_H
+
+#include <glad/glad.h> 
+
+#include <glm/glm.hpp>
+#include <glm/gtc/matrix_transform.hpp>
+#define STB_IMAGE_IMPLEMENTATION
+#include "stb_image.h"
+#include <assimp/Importer.hpp>
+#include <assimp/scene.h>
+#include <assimp/postprocess.h>
+
+#include <myEngine/mesh.hpp>
+#include <myEngine/shader.hpp>
+
+#include <string>
+#include <fstream>
+#include <sstream>
+#include <iostream>
+#include <map>
+#include <vector>
+using namespace std;
+
+unsigned int TextureFromFile(const char *path, const string &directory, bool gamma = false);
+
+class Model 
+{
+public:
+	// model data 
+	vector<Texture> textures_loaded;	// stores all the textures loaded so far, optimization to make sure textures aren't loaded more than once.
+	vector<Mesh>    meshes;
+	string directory;
+	bool gammaCorrection;
+
+	// constructor, expects a filepath to a 3D model.
+	Model(string const &path, bool gamma = false) : gammaCorrection(gamma)
+	{
+		loadModel(path);
+	}
+
+	// draws the model, and thus all its meshes
+	void Draw(Shader &shader)
+	{
+		for(unsigned int i = 0; i < meshes.size(); i++)
+			meshes[i].Draw(shader);
+	}
+	
+private:
+	// loads a model with supported ASSIMP extensions from file and stores the resulting meshes in the meshes vector.
+	void loadModel(string const &path)
+	{
+		// read file via ASSIMP
+		Assimp::Importer importer;
+		const aiScene* scene = importer.ReadFile(path, aiProcess_Triangulate | aiProcess_GenSmoothNormals | aiProcess_FlipUVs | aiProcess_CalcTangentSpace);
+		// check for errors
+		if(!scene || scene->mFlags & AI_SCENE_FLAGS_INCOMPLETE || !scene->mRootNode) // if is Not Zero
+		{
+			cout << "ERROR::ASSIMP:: " << importer.GetErrorString() << endl;
+			return;
+		}
+		// retrieve the directory path of the filepath
+		directory = path.substr(0, path.find_last_of('/'));
+
+		// process ASSIMP's root node recursively
+		processNode(scene->mRootNode, scene);
+	}
+
+	// processes a node in a recursive fashion. Processes each individual mesh located at the node and repeats this process on its children nodes (if any).
+	void processNode(aiNode *node, const aiScene *scene)
+	{
+		// process each mesh located at the current node
+		for(unsigned int i = 0; i < node->mNumMeshes; i++)
+		{
+			// the node object only contains indices to index the actual objects in the scene. 
+			// the scene contains all the data, node is just to keep stuff organized (like relations between nodes).
+			aiMesh* mesh = scene->mMeshes[node->mMeshes[i]];
+			meshes.push_back(processMesh(mesh, scene));
+		}
+		// after we've processed all of the meshes (if any) we then recursively process each of the children nodes
+		for(unsigned int i = 0; i < node->mNumChildren; i++)
+		{
+			processNode(node->mChildren[i], scene);
+		}
+
+	}
+
+	Mesh processMesh(aiMesh *mesh, const aiScene *scene)
+	{
+		// data to fill
+		vector<Vertex> vertices;
+		vector<unsigned int> indices;
+		vector<Texture> textures;
+
+		// walk through each of the mesh's vertices
+		for(unsigned int i = 0; i < mesh->mNumVertices; i++)
+		{
+			Vertex vertex;
+			glm::vec3 vector; // we declare a placeholder vector since assimp uses its own vector class that doesn't directly convert to glm's vec3 class so we transfer the data to this placeholder glm::vec3 first.
+			// positions
+			vector.x = mesh->mVertices[i].x;
+			vector.y = mesh->mVertices[i].y;
+			vector.z = mesh->mVertices[i].z;
+			vertex.Position = vector;
+			// normals
+			if (mesh->HasNormals())
+			{
+				vector.x = mesh->mNormals[i].x;
+				vector.y = mesh->mNormals[i].y;
+				vector.z = mesh->mNormals[i].z;
+				vertex.Normal = vector;
+			}
+			// texture coordinates
+			if(mesh->mTextureCoords[0]) // does the mesh contain texture coordinates?
+			{
+				glm::vec2 vec;
+				// a vertex can contain up to 8 different texture coordinates. We thus make the assumption that we won't 
+				// use models where a vertex can have multiple texture coordinates so we always take the first set (0).
+				vec.x = mesh->mTextureCoords[0][i].x; 
+				vec.y = mesh->mTextureCoords[0][i].y;
+				vertex.TexCoords = vec;
+				// tangent
+				vector.x = mesh->mTangents[i].x;
+				vector.y = mesh->mTangents[i].y;
+				vector.z = mesh->mTangents[i].z;
+				vertex.Tangent = vector;
+				// bitangent
+				vector.x = mesh->mBitangents[i].x;
+				vector.y = mesh->mBitangents[i].y;
+				vector.z = mesh->mBitangents[i].z;
+				vertex.Bitangent = vector;
+			}
+			else
+				vertex.TexCoords = glm::vec2(0.0f, 0.0f);
+
+			vertices.push_back(vertex);
+		}
+		// now wak through each of the mesh's faces (a face is a mesh its triangle) and retrieve the corresponding vertex indices.
+		for(unsigned int i = 0; i < mesh->mNumFaces; i++)
+		{
+			aiFace face = mesh->mFaces[i];
+			// retrieve all indices of the face and store them in the indices vector
+			for(unsigned int j = 0; j < face.mNumIndices; j++)
+				indices.push_back(face.mIndices[j]);        
+		}
+		// process materials
+		aiMaterial* material = scene->mMaterials[mesh->mMaterialIndex];    
+		// we assume a convention for sampler names in the shaders. Each diffuse texture should be named
+		// as 'texture_diffuseN' where N is a sequential number ranging from 1 to MAX_SAMPLER_NUMBER. 
+		// Same applies to other texture as the following list summarizes:
+		// diffuse: texture_diffuseN
+		// specular: texture_specularN
+		// normal: texture_normalN
+
+		// 1. diffuse maps
+		vector<Texture> diffuseMaps = loadMaterialTextures(material, aiTextureType_DIFFUSE, "texture_diffuse");
+		textures.insert(textures.end(), diffuseMaps.begin(), diffuseMaps.end());
+		// 2. specular maps
+		vector<Texture> specularMaps = loadMaterialTextures(material, aiTextureType_SPECULAR, "texture_specular");
+		textures.insert(textures.end(), specularMaps.begin(), specularMaps.end());
+		// 3. normal maps
+		std::vector<Texture> normalMaps = loadMaterialTextures(material, aiTextureType_HEIGHT, "texture_normal");
+		textures.insert(textures.end(), normalMaps.begin(), normalMaps.end());
+		// 4. height maps
+		std::vector<Texture> heightMaps = loadMaterialTextures(material, aiTextureType_AMBIENT, "texture_height");
+		textures.insert(textures.end(), heightMaps.begin(), heightMaps.end());
+		
+		// return a mesh object created from the extracted mesh data
+		return Mesh(vertices, indices, textures);
+	}
+
+	// checks all material textures of a given type and loads the textures if they're not loaded yet.
+	// the required info is returned as a Texture struct.
+	vector<Texture> loadMaterialTextures(aiMaterial *mat, aiTextureType type, string typeName)
+	{
+		vector<Texture> textures;
+		for(unsigned int i = 0; i < mat->GetTextureCount(type); i++)
+		{
+			aiString str;
+			mat->GetTexture(type, i, &str);
+			// check if texture was loaded before and if so, continue to next iteration: skip loading a new texture
+			bool skip = false;
+			for(unsigned int j = 0; j < textures_loaded.size(); j++)
+			{
+				if(std::strcmp(textures_loaded[j].path.data(), str.C_Str()) == 0)
+				{
+					textures.push_back(textures_loaded[j]);
+					skip = true; // a texture with the same filepath has already been loaded, continue to next one. (optimization)
+					break;
+				}
+			}
+			if(!skip)
+			{   // if texture hasn't been loaded already, load it
+				Texture texture;
+				texture.id = TextureFromFile(str.C_Str(), this->directory);
+				texture.type = typeName;
+				texture.path = str.C_Str();
+				textures.push_back(texture);
+				textures_loaded.push_back(texture);  // store it as texture loaded for entire model, to ensure we won't unnecessary load duplicate textures.
+			}
+		}
+		return textures;
+	}
+};
+
+
+unsigned int TextureFromFile(const char *path, const string &directory, bool gamma)
+{
+	string filename = string(path);
+	filename = directory + '/' + filename;
+
+	unsigned int textureID;
+	glGenTextures(1, &textureID);
+
+	int width, height, nrComponents;
+	unsigned char *data = stbi_load(filename.c_str(), &width, &height, &nrComponents, 0);
+	if (data)
+	{
+		GLenum format;
+		if (nrComponents == 1)
+			format = GL_RED;
+		else if (nrComponents == 3)
+			format = GL_RGB;
+		else if (nrComponents == 4)
+			format = GL_RGBA;
+
+		glBindTexture(GL_TEXTURE_2D, textureID);
+		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
+	{
+		std::cout << "Texture failed to load at path: " << path << std::endl;
+		stbi_image_free(data);
+	}
+
+	return textureID;
+}
+#endif