OpenGL之——天空盒

main.cpp

// Std. Includes
#include <string>
#include <algorithm>
using namespace std;

// GLEW
#define GLEW_STATIC
#include <GL/glew.h>

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

// GL includes
#include "Shader.h"
#include "Camera.h"
#include "Model.h"

// GLM Mathemtics
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <GL/glut.h>
#include <SOIL.h>
// Other Libs
#pragma comment(lib,"glew32s.lib")
#pragma comment(lib,"glfw3.lib")
#pragma comment(lib,"SOIL.lib")
// Properties
// Properties
GLuint screenWidth = 800, screenHeight = 600;

// Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
void scroll_callback(GLFWwindow* window, double xoffset, double yoffset);
void mouse_callback(GLFWwindow* window, double xpos, double ypos);
void Do_Movement();
GLuint loadTexture(GLchar* path, GLboolean alpha = false);
GLuint loadCubemap(vector<const GLchar*> faces);

// Camera
Camera camera(glm::vec3(0.0f, 0.0f, 3.0f));
bool keys[1024];
GLfloat lastX = 200, lastY = 300;
bool firstMouse = true;

GLfloat deltaTime = 0.0f;
GLfloat lastFrame = 0.0f;



// The MAIN function, from here we start our application and run our Game loop
int main()
{
	// Init GLFW
	glfwInit();
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
	glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);

	GLFWwindow* window = glfwCreateWindow(screenWidth, screenHeight, "LearnOpenGL", nullptr, nullptr); // Windowed
	glfwMakeContextCurrent(window);

	// Set the required callback functions
	glfwSetKeyCallback(window, key_callback);
	glfwSetCursorPosCallback(window, mouse_callback);
	glfwSetScrollCallback(window, scroll_callback);

	// Options
	glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);

	// Initialize GLEW to setup the OpenGL Function pointers
	glewExperimental = GL_TRUE;
	glewInit();
	glGetError(); // Debug GLEW bug fix

	// Define the viewport dimensions
	glViewport(0, 0, screenWidth, screenHeight);

	// Setup some OpenGL options
	glEnable(GL_DEPTH_TEST);
	glDepthFunc(GL_LESS);

	// Setup and compile our shaders
	Shader shader("advanced.vs", "advanced.frag");
	Shader skyboxShader("skybox.vs", "skybox.frag");

#pragma region "object_initialization"
	GLfloat skyboxVertices[] = {
		// Positions          
		-1.0f,  1.0f, -1.0f,
		-1.0f, -1.0f, -1.0f,
		 1.0f, -1.0f, -1.0f,
		 1.0f, -1.0f, -1.0f,
		 1.0f,  1.0f, -1.0f,
		-1.0f,  1.0f, -1.0f,

		-1.0f, -1.0f,  1.0f,
		-1.0f, -1.0f, -1.0f,
		-1.0f,  1.0f, -1.0f,
		-1.0f,  1.0f, -1.0f,
		-1.0f,  1.0f,  1.0f,
		-1.0f, -1.0f,  1.0f,

		 1.0f, -1.0f, -1.0f,
		 1.0f, -1.0f,  1.0f,
		 1.0f,  1.0f,  1.0f,
		 1.0f,  1.0f,  1.0f,
		 1.0f,  1.0f, -1.0f,
		 1.0f, -1.0f, -1.0f,

		-1.0f, -1.0f,  1.0f,
		-1.0f,  1.0f,  1.0f,
		 1.0f,  1.0f,  1.0f,
		 1.0f,  1.0f,  1.0f,
		 1.0f, -1.0f,  1.0f,
		-1.0f, -1.0f,  1.0f,

		-1.0f,  1.0f, -1.0f,
		 1.0f,  1.0f, -1.0f,
		 1.0f,  1.0f,  1.0f,
		 1.0f,  1.0f,  1.0f,
		-1.0f,  1.0f,  1.0f,
		-1.0f,  1.0f, -1.0f,

		-1.0f, -1.0f, -1.0f,
		-1.0f, -1.0f,  1.0f,
		 1.0f, -1.0f, -1.0f,
		 1.0f, -1.0f, -1.0f,
		-1.0f, -1.0f,  1.0f,
		 1.0f, -1.0f,  1.0f
	};
	// Setup skybox VAO
	GLuint skyboxVAO, skyboxVBO;
	glGenVertexArrays(1, &skyboxVAO);
	glGenBuffers(1, &skyboxVBO);
	glBindVertexArray(skyboxVAO);
	glBindBuffer(GL_ARRAY_BUFFER, skyboxVBO);
	glBufferData(GL_ARRAY_BUFFER, sizeof(skyboxVertices), &skyboxVertices, GL_STATIC_DRAW);
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), (GLvoid*)0);
	glBindVertexArray(0);

#pragma endregion

	// Cubemap (Skybox)
	vector<const GLchar*> faces;
	faces.push_back("skybox/right.jpg");
	faces.push_back("skybox/left.jpg");
	faces.push_back("skybox/top.jpg");
	faces.push_back("skybox/bottom.jpg");
	faces.push_back("skybox/back.jpg");
	faces.push_back("skybox/front.jpg");
	GLuint skyboxTexture = loadCubemap(faces);

	// Load nanosuit using our model loader
	Model nanosuit((GLchar*)("nanosuit/nanosuit.obj"));

	// Draw as wireframe
	//glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);

	// Game loop
	while (!glfwWindowShouldClose(window))
	{
		// Set frame time
		GLfloat currentFrame = glfwGetTime();
		deltaTime = currentFrame - lastFrame;
		lastFrame = currentFrame;

		// Check and call events
		glfwPollEvents();
		Do_Movement();

		// Clear buffers
		glClearColor(0.1f, 0.1f, 0.1f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);


		// Draw scene as normal
		shader.Use();
		glm::mat4 model;
		glm::mat4 view = camera.GetViewMatrix();
		glm::mat4 projection = glm::perspective(camera.Zoom, (float)screenWidth / (float)screenHeight, 0.1f, 100.0f);
		glUniformMatrix4fv(glGetUniformLocation(shader.Program, "model"), 1, GL_FALSE, glm::value_ptr(model));
		glUniformMatrix4fv(glGetUniformLocation(shader.Program, "view"), 1, GL_FALSE, glm::value_ptr(view));
		glUniformMatrix4fv(glGetUniformLocation(shader.Program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
		glUniform3f(glGetUniformLocation(shader.Program, "cameraPos"), camera.Position.x, camera.Position.y, camera.Position.z);

		glActiveTexture(GL_TEXTURE3); // We already have 3 texture units active (in this shader) so set the skybox as the 4th texture unit (texture units are 0 based so index number 3)
		glUniform1i(glGetUniformLocation(shader.Program, "skybox"), 3);
		// Now draw the nanosuit
		glBindTexture(GL_TEXTURE_CUBE_MAP, skyboxTexture);
		nanosuit.Draw(shader);

		// Draw skybox as last
		glDepthFunc(GL_LEQUAL);  // Change depth function so depth test passes when values are equal to depth buffer's content
		skyboxShader.Use();
		view = glm::mat4(glm::mat3(camera.GetViewMatrix()));	// Remove any translation component of the view matrix
		glUniformMatrix4fv(glGetUniformLocation(skyboxShader.Program, "view"), 1, GL_FALSE, glm::value_ptr(view));
		glUniformMatrix4fv(glGetUniformLocation(skyboxShader.Program, "projection"), 1, GL_FALSE, glm::value_ptr(projection));
		// skybox cube
		glBindVertexArray(skyboxVAO);
		glActiveTexture(GL_TEXTURE0);
		glUniform1i(glGetUniformLocation(shader.Program, "skybox"), 0);
		glBindTexture(GL_TEXTURE_CUBE_MAP, skyboxTexture);
		glDrawArrays(GL_TRIANGLES, 0, 36);
		glBindVertexArray(0);
		glDepthFunc(GL_LESS); // Set depth function back to default


		// Swap the buffers
		glfwSwapBuffers(window);
	}

	glfwTerminate();
	return 0;
}

// Loads a cubemap texture from 6 individual texture faces
// Order should be:
// +X (right)
// -X (left)
// +Y (top)
// -Y (bottom)
// +Z (front)
// -Z (back)
GLuint loadCubemap(vector<const GLchar*> faces)
{
	GLuint textureID;
	glGenTextures(1, &textureID);

	int width, height;
	unsigned char* image;

	glBindTexture(GL_TEXTURE_CUBE_MAP, textureID);
	for (GLuint i = 0; i < faces.size(); i++)
	{
		image = SOIL_load_image(faces[i], &width, &height, 0, SOIL_LOAD_RGB);
		glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
		SOIL_free_image_data(image);
	}
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
	glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
	glBindTexture(GL_TEXTURE_CUBE_MAP, 0);

	return textureID;
}


// This function loads a texture from file. Note: texture loading functions like these are usually 
// managed by a 'Resource Manager' that manages all resources (like textures, models, audio). 
// For learning purposes we'll just define it as a utility function.
GLuint loadTexture(GLchar* path)
{
	//Generate texture ID and load texture data 
	GLuint textureID;
	glGenTextures(1, &textureID);
	int width, height;
	unsigned char* image = SOIL_load_image(path, &width, &height, 0, SOIL_LOAD_RGB);
	// Assign texture to ID
	glBindTexture(GL_TEXTURE_2D, textureID);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
	glGenerateMipmap(GL_TEXTURE_2D);

	// Parameters
	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);
	glBindTexture(GL_TEXTURE_2D, 0);
	SOIL_free_image_data(image);
	return textureID;
}

#pragma region "User input"

// Moves/alters the camera positions based on user input
void Do_Movement()
{
	// Camera controls
	if (keys[GLFW_KEY_W])
		camera.ProcessKeyboard(FORWARD, deltaTime);
	if (keys[GLFW_KEY_S])
		camera.ProcessKeyboard(BACKWARD, deltaTime);
	if (keys[GLFW_KEY_A])
		camera.ProcessKeyboard(LEFT, deltaTime);
	if (keys[GLFW_KEY_D])
		camera.ProcessKeyboard(RIGHT, deltaTime);
}

// Is called whenever a key is pressed/released via GLFW
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode)
{
	if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
		glfwSetWindowShouldClose(window, GL_TRUE);

	if (action == GLFW_PRESS)
		keys[key] = true;
	else if (action == GLFW_RELEASE)
		keys[key] = false;
}

void mouse_callback(GLFWwindow* window, double xpos, double ypos)
{
	if (firstMouse)
	{
		lastX = xpos;
		lastY = ypos;
		firstMouse = false;
	}

	GLfloat xoffset = xpos - lastX;
	GLfloat yoffset = lastY - ypos;

	lastX = xpos;
	lastY = ypos;

	camera.ProcessMouseMovement(xoffset, yoffset);
}

void scroll_callback(GLFWwindow* window, double xoffset, double yoffset)
{
	camera.ProcessMouseScroll(yoffset);
}

#pragma endregion

Model.h

#pragma once
// Std. Includes
#include <string>
#include <fstream>
#include <sstream>
#include <iostream>
#include <map>
#include <vector>
using namespace std;
// GL Includes
#include <GL/glew.h> // Contains all the necessery OpenGL includes
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <SOIL.h>
#include <assimp/Importer.hpp>
#include <assimp/scene.h>
#include <assimp/postprocess.h>
#pragma comment(lib,"assimpd.lib")
#include "Mesh.h"

GLint TextureFromFile(const char* path, string directory);

class Model
{
public:
	/*  Functions   */
	// Constructor, expects a filepath to a 3D model.
	Model(GLchar* path)
	{
		this->loadModel(path);
	}

	// Draws the model, and thus all its meshes
	void Draw(Shader shader)
	{
		for (GLuint i = 0; i < this->meshes.size(); i++)
			this->meshes[i].Draw(shader);
	}

private:
	/*  Model Data  */
	vector<Mesh> meshes;
	string directory;
	vector<Texture> textures_loaded;	// Stores all the textures loaded so far, optimization to make sure textures aren't loaded more than once.

	/*  Functions   */
	// Loads a model with supported ASSIMP extensions from file and stores the resulting meshes in the meshes vector.
	void loadModel(string path)
	{
		// Read file via ASSIMP
		Assimp::Importer importer;
		const aiScene* scene = importer.ReadFile(path, aiProcess_Triangulate | aiProcess_FlipUVs);
		// 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
		this->directory = path.substr(0, path.find_last_of('/'));

		// Process ASSIMP's root node recursively
		this->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 (GLuint 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.
			aiMesh* mesh = scene->mMeshes[node->mMeshes[i]];
			this->meshes.push_back(this->processMesh(mesh, scene));
		}
		// After we've processed all of the meshes (if any) we then recursively process each of the children nodes
		for (GLuint i = 0; i < node->mNumChildren; i++)
		{
			// Child nodes are actually stored in the node, not in the scene (which makes sense since nodes only contain
			// links and indices, nothing more, so why store that in the scene)
			this->processNode(node->mChildren[i], scene);
		}

	}

	Mesh processMesh(aiMesh* mesh, const aiScene* scene)
	{
		// Data to fill
		vector<Vertex> vertices;
		vector<GLuint> indices;
		vector<Texture> textures;

		// Walk through each of the mesh's vertices
		for (GLuint 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
			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;
			}
			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 (GLuint 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 (GLuint j = 0; j < face.mNumIndices; j++)
				indices.push_back(face.mIndices[j]);
		}
		// Process materials
		if (mesh->mMaterialIndex >= 0)
		{
			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 = this->loadMaterialTextures(material, aiTextureType_DIFFUSE, "texture_diffuse");
			textures.insert(textures.end(), diffuseMaps.begin(), diffuseMaps.end());
			// 2. Specular maps
			vector<Texture> specularMaps = this->loadMaterialTextures(material, aiTextureType_SPECULAR, "texture_specular");
			textures.insert(textures.end(), specularMaps.begin(), specularMaps.end());
			// 3. Reflection maps (Note that ASSIMP doesn't load reflection maps properly from wavefront objects, so we'll cheat a little by defining the reflection maps as ambient maps in the .obj file, which ASSIMP is able to load)
			vector<Texture> reflectionMaps = this->loadMaterialTextures(material, aiTextureType_AMBIENT, "texture_reflection");
			textures.insert(textures.end(), reflectionMaps.begin(), reflectionMaps.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 (GLuint 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
			GLboolean skip = false;
			for (GLuint j = 0; j < textures_loaded.size(); j++)
			{
				if (textures_loaded[j].path == str)
				{
					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;
				textures.push_back(texture);
				this->textures_loaded.push_back(texture);  // Store it as texture loaded for entire model, to ensure we won't unnecesery load duplicate textures.
			}
		}
		return textures;
	}
};




GLint TextureFromFile(const char* path, string directory)
{
	//Generate texture ID and load texture data 
	string filename = string(path);
	filename = directory + '/' + filename;
	GLuint textureID;
	glGenTextures(1, &textureID);
	int width, height;
	unsigned char* image = SOIL_load_image(filename.c_str(), &width, &height, 0, SOIL_LOAD_RGB);
	// Assign texture to ID
	glBindTexture(GL_TEXTURE_2D, textureID);
	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, image);
	glGenerateMipmap(GL_TEXTURE_2D);

	// Parameters
	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);
	glBindTexture(GL_TEXTURE_2D, 0);
	SOIL_free_image_data(image);
	return textureID;
}

Camera.h

#pragma once

// Std. Includes
#include <vector>

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



// Defines several possible options for camera movement. Used as abstraction to stay away from window-system specific input methods
enum Camera_Movement {
	FORWARD,
	BACKWARD,
	LEFT,
	RIGHT
};

// Default camera values
const GLfloat YAW = -90.0f;
const GLfloat PITCH = 0.0f;
const GLfloat SPEED = 10.0f;
const GLfloat SENSITIVTY = 0.25f;
const GLfloat ZOOM = 45.0f;


// An abstract camera class that processes input and calculates the corresponding Eular Angles, Vectors and Matrices for use in OpenGL
class Camera
{
public:
	// Camera Attributes
	glm::vec3 Position;
	glm::vec3 Front;
	glm::vec3 Up;
	glm::vec3 Right;
	glm::vec3 WorldUp;
	// Eular Angles
	GLfloat Yaw;
	GLfloat Pitch;
	// Camera options
	GLfloat MovementSpeed;
	GLfloat MouseSensitivity;
	GLfloat Zoom;

	// Constructor with vectors
	Camera(glm::vec3 position = glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3 up = glm::vec3(0.0f, 1.0f, 0.0f), GLfloat yaw = YAW, GLfloat pitch = PITCH) : Front(glm::vec3(0.0f, 0.0f, -1.0f)), MovementSpeed(SPEED), MouseSensitivity(SENSITIVTY), Zoom(ZOOM)
	{
		this->Position = position;
		this->WorldUp = up;
		this->Yaw = yaw;
		this->Pitch = pitch;
		this->updateCameraVectors();
	}
	// Constructor with scalar values
	Camera(GLfloat posX, GLfloat posY, GLfloat posZ, GLfloat upX, GLfloat upY, GLfloat upZ, GLfloat yaw, GLfloat pitch) : Front(glm::vec3(0.0f, 0.0f, -1.0f)), MovementSpeed(SPEED), MouseSensitivity(SENSITIVTY), Zoom(ZOOM)
	{
		this->Position = glm::vec3(posX, posY, posZ);
		this->WorldUp = glm::vec3(upX, upY, upZ);
		this->Yaw = yaw;
		this->Pitch = pitch;
		this->updateCameraVectors();
	}

	// Returns the view matrix calculated using Eular Angles and the LookAt Matrix
	glm::mat4 GetViewMatrix()
	{
		return glm::lookAt(this->Position, this->Position + this->Front, this->Up);
	}

	// Processes input received from any keyboard-like input system. Accepts input parameter in the form of camera defined ENUM (to abstract it from windowing systems)
	void ProcessKeyboard(Camera_Movement direction, GLfloat deltaTime)
	{
		GLfloat velocity = this->MovementSpeed * deltaTime;
		if (direction == FORWARD)
			this->Position += this->Front * velocity;
		if (direction == BACKWARD)
			this->Position -= this->Front * velocity;
		if (direction == LEFT)
			this->Position -= this->Right * velocity;
		if (direction == RIGHT)
			this->Position += this->Right * velocity;
	}

	// Processes input received from a mouse input system. Expects the offset value in both the x and y direction.
	void ProcessMouseMovement(GLfloat xoffset, GLfloat yoffset, GLboolean constrainPitch = true)
	{
		xoffset *= this->MouseSensitivity;
		yoffset *= this->MouseSensitivity;

		this->Yaw += xoffset;
		this->Pitch += yoffset;

		// Make sure that when pitch is out of bounds, screen doesn't get flipped
		if (constrainPitch)
		{
			if (this->Pitch > 89.0f)
				this->Pitch = 89.0f;
			if (this->Pitch < -89.0f)
				this->Pitch = -89.0f;
		}

		// Update Front, Right and Up Vectors using the updated Eular angles
		this->updateCameraVectors();
	}

	// Processes input received from a mouse scroll-wheel event. Only requires input on the vertical wheel-axis
	void ProcessMouseScroll(GLfloat yoffset)
	{
		if (this->Zoom >= 1.0f && this->Zoom <= 45.0f)
			this->Zoom -= yoffset;
		if (this->Zoom <= 1.0f)
			this->Zoom = 1.0f;
		if (this->Zoom >= 45.0f)
			this->Zoom = 45.0f;
	}

private:
	// Calculates the front vector from the Camera's (updated) Eular Angles
	void updateCameraVectors()
	{
		// Calculate the new Front vector
		glm::vec3 front;
		front.x = cos(glm::radians(this->Yaw)) * cos(glm::radians(this->Pitch));
		front.y = sin(glm::radians(this->Pitch));
		front.z = sin(glm::radians(this->Yaw)) * cos(glm::radians(this->Pitch));
		this->Front = glm::normalize(front);
		// Also re-calculate the Right and Up vector
		this->Right = glm::normalize(glm::cross(this->Front, this->WorldUp));  // Normalize the vectors, because their length gets closer to 0 the more you look up or down which results in slower movement.
		this->Up = glm::normalize(glm::cross(this->Right, this->Front));
	}
};

Mesh.h

#pragma once
// Std. Includes
#include <string>
#include <fstream>
#include <sstream>
#include <iostream>
#include <vector>
using namespace std;
// GL Includes
#include <GL/glew.h> // Contains all the necessery OpenGL includes
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>


struct Vertex {
	// Position
	glm::vec3 Position;
	// Normal
	glm::vec3 Normal;
	// TexCoords
	glm::vec2 TexCoords;
};

struct Texture {
	GLuint id;
	string type;
	aiString path;
};

class Mesh {
public:
	/*  Mesh Data  */
	vector<Vertex> vertices;
	vector<GLuint> indices;
	vector<Texture> textures;

	/*  Functions  */
	// Constructor
	Mesh(vector<Vertex> vertices, vector<GLuint> indices, vector<Texture> textures)
	{
		this->vertices = vertices;
		this->indices = indices;
		this->textures = textures;

		// Now that we have all the required data, set the vertex buffers and its attribute pointers.
		this->setupMesh();
	}

	// Render the mesh
	void Draw(Shader shader)
	{
		// Bind appropriate textures
		GLuint diffuseNr = 1;
		GLuint specularNr = 1;
		GLuint reflectionNr = 1;

		for (GLuint i = 0; i < this->textures.size(); i++)
		{
			glActiveTexture(GL_TEXTURE0 + i); // Active proper texture unit before binding
			// Retrieve texture number (the N in diffuse_textureN)
			stringstream ss;
			string number;
			string name = this->textures[i].type;
			if (name == "texture_diffuse")
				ss << diffuseNr++; // Transfer GLuint to stream
			else if (name == "texture_specular")
				ss << specularNr++; // Transfer GLuint to stream
			else if (name == "texture_reflection")	// We'll now also need to add the code to set and bind to reflection textures
				ss << reflectionNr++;
			number = ss.str();
			// Now set the sampler to the correct texture unit
			glUniform1i(glGetUniformLocation(shader.Program, (name + number).c_str()), i);

			// And finally bind the texture
			glBindTexture(GL_TEXTURE_2D, this->textures[i].id);
		}
		glActiveTexture(GL_TEXTURE0); // Always good practice to set everything back to defaults once configured.

		// Also set each mesh's shininess property to a default value (if you want you could extend this to another mesh property and possibly change this value)
		//glUniform1f(glGetUniformLocation(shader.Program, "material.shininess"), 16.0f);

		// Draw mesh
		glBindVertexArray(this->VAO);
		glDrawElements(GL_TRIANGLES, this->indices.size(), GL_UNSIGNED_INT, 0);
		glBindVertexArray(0);
	}

private:
	/*  Render data  */
	GLuint VAO, VBO, EBO;

	/*  Functions    */
	// Initializes all the buffer objects/arrays
	void setupMesh()
	{
		// Create buffers/arrays
		glGenVertexArrays(1, &this->VAO);
		glGenBuffers(1, &this->VBO);
		glGenBuffers(1, &this->EBO);

		glBindVertexArray(this->VAO);
		// Load data into vertex buffers
		glBindBuffer(GL_ARRAY_BUFFER, this->VBO);
		// A great thing about structs is that their memory layout is sequential for all its items.
		// The effect is that we can simply pass a pointer to the struct and it translates perfectly to a glm::vec3/2 array which
		// again translates to 3/2 floats which translates to a byte array.
		glBufferData(GL_ARRAY_BUFFER, this->vertices.size() * sizeof(Vertex), &this->vertices[0], GL_STATIC_DRAW);

		glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, this->EBO);
		glBufferData(GL_ELEMENT_ARRAY_BUFFER, this->indices.size() * sizeof(GLuint), &this->indices[0], GL_STATIC_DRAW);

		// Set the vertex attribute pointers
		// Vertex Positions
		glEnableVertexAttribArray(0);
		glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)0);
		// Vertex Normals
		glEnableVertexAttribArray(1);
		glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)offsetof(Vertex, Normal));
		// Vertex Texture Coords
		glEnableVertexAttribArray(2);
		glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)offsetof(Vertex, TexCoords));

		glBindVertexArray(0);
	}
};

Shader.h

#ifndef SHADER_H
#define SHADER_H

#include <string>
#include <fstream>
#include <sstream>
#include <iostream>

#include <GL/glew.h>

class Shader
{
public:
	GLuint Program;
	// Constructor generates the shader on the fly
	Shader(const GLchar* vertexPath, const GLchar* fragmentPath)
	{
		// 1. Retrieve the vertex/fragment source code from filePath
		std::string vertexCode;
		std::string fragmentCode;
		std::ifstream vShaderFile;
		std::ifstream fShaderFile;
		// ensures ifstream objects can throw exceptions:
		vShaderFile.exceptions(std::ifstream::badbit);
		fShaderFile.exceptions(std::ifstream::badbit);
		try
		{
			// Open files
			vShaderFile.open(vertexPath);
			fShaderFile.open(fragmentPath);
			std::stringstream vShaderStream, fShaderStream;
			// Read file's buffer contents into streams
			vShaderStream << vShaderFile.rdbuf();
			fShaderStream << fShaderFile.rdbuf();
			// close file handlers
			vShaderFile.close();
			fShaderFile.close();
			// Convert stream into string
			vertexCode = vShaderStream.str();
			fragmentCode = fShaderStream.str();
		}
		catch (std::ifstream::failure e)
		{
			std::cout << "ERROR::SHADER::FILE_NOT_SUCCESFULLY_READ" << std::endl;
		}
		const GLchar* vShaderCode = vertexCode.c_str();
		const GLchar * fShaderCode = fragmentCode.c_str();
		// 2. Compile shaders
		GLuint vertex, fragment;
		GLint success;
		GLchar infoLog[512];
		// Vertex Shader
		vertex = glCreateShader(GL_VERTEX_SHADER);
		glShaderSource(vertex, 1, &vShaderCode, NULL);
		glCompileShader(vertex);
		// Print compile errors if any
		glGetShaderiv(vertex, GL_COMPILE_STATUS, &success);
		if (!success)
		{
			glGetShaderInfoLog(vertex, 512, NULL, infoLog);
			std::cout << "ERROR::SHADER::VERTEX::COMPILATION_FAILED\n" << infoLog << std::endl;
		}
		// Fragment Shader
		fragment = glCreateShader(GL_FRAGMENT_SHADER);
		glShaderSource(fragment, 1, &fShaderCode, NULL);
		glCompileShader(fragment);
		// Print compile errors if any
		glGetShaderiv(fragment, GL_COMPILE_STATUS, &success);
		if (!success)
		{
			glGetShaderInfoLog(fragment, 512, NULL, infoLog);
			std::cout << "ERROR::SHADER::FRAGMENT::COMPILATION_FAILED1\n" << infoLog << std::endl;
		}
		// Shader Program
		this->Program = glCreateProgram();
		glAttachShader(this->Program, vertex);
		glAttachShader(this->Program, fragment);
		glLinkProgram(this->Program);
		// Print linking errors if any
		glGetProgramiv(this->Program, GL_LINK_STATUS, &success);
		if (!success)
		{
			glGetProgramInfoLog(this->Program, 512, NULL, infoLog);
			std::cout << "ERROR::SHADER::PROGRAM::LINKING_FAILED\n" << infoLog << std::endl;
		}
		// Delete the shaders as they're linked into our program now and no longer necessery
		glDeleteShader(vertex);
		glDeleteShader(fragment);

	}
	// Uses the current shader
	void Use()
	{
		glUseProgram(this->Program);
	}
};

#endif

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