Lecture4.cpp

#include <iostream>

// GLAD
#include <glad/glad.h>

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

// GLM Mathematics
#include "glm/glm.hpp"
#include "glm/gtc/matrix_transform.hpp"
#include "glm/gtc/type_ptr.hpp"

// Other includes
#include "shader.h"


// Function prototypes
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);

// Window dimensions
const GLuint WIDTH = 800, HEIGHT = 600;

// The MAIN function, from here we start the application and run the game loop
int main()
{
	// Init GLFW
	glfwInit();
	// Set all the required options for GLFW
	glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
	glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 1);
    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
	glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
	glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);

	// Create a GLFWwindow object that we can use for GLFW's functions
	GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, "LearnOpenGL", nullptr, nullptr);
	glfwMakeContextCurrent(window);

	// Set the required callback functions
	glfwSetKeyCallback(window, key_callback);

	// Initialize GLAD to setup the OpenGL Function pointers
	if (!gladLoadGLLoader((GLADloadproc)glfwGetProcAddress))
	{
		std::cout << "Failed to initialize glad" << std::endl;
		return -1;
	};

	// Define the viewport dimensions
	glViewport(0, 0, WIDTH, HEIGHT);

	// Setup OpenGL options
	glEnable(GL_DEPTH_TEST);


	// Build and compile our shader program
	Shader ourShader("main.vert.glsl", "main.frag.glsl");


	// Set up vertex data (and buffer(s)) and attribute pointers
	GLfloat vertices[] = {
		-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,
		0.5f, -0.5f, -0.5f, 1.0f, 0.0f,
		0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
		0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
		-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
		-0.5f, -0.5f, -0.5f, 0.0f, 0.0f,

		-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
		0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
		0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
		0.5f, 0.5f, 0.5f, 1.0f, 1.0f,
		-0.5f, 0.5f, 0.5f, 0.0f, 1.0f,
		-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,

		-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
		-0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
		-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
		-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
		-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
		-0.5f, 0.5f, 0.5f, 1.0f, 0.0f,

		0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
		0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
		0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
		0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
		0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
		0.5f, 0.5f, 0.5f, 1.0f, 0.0f,

		-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,
		0.5f, -0.5f, -0.5f, 1.0f, 1.0f,
		0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
		0.5f, -0.5f, 0.5f, 1.0f, 0.0f,
		-0.5f, -0.5f, 0.5f, 0.0f, 0.0f,
		-0.5f, -0.5f, -0.5f, 0.0f, 1.0f,

		-0.5f, 0.5f, -0.5f, 0.0f, 1.0f,
		0.5f, 0.5f, -0.5f, 1.0f, 1.0f,
		0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
		0.5f, 0.5f, 0.5f, 1.0f, 0.0f,
		-0.5f, 0.5f, 0.5f, 0.0f, 0.0f,
		-0.5f, 0.5f, -0.5f, 0.0f, 1.0f
	};
	GLuint VBO, VAO;
	glGenVertexArrays(1, &VAO);
	glGenBuffers(1, &VBO);

	glBindVertexArray(VAO);

	glBindBuffer(GL_ARRAY_BUFFER, VBO);
	glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);

	// Position attribute
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)0);
	glEnableVertexAttribArray(0);
	// TexCoord attribute
	glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, 5 * sizeof(GLfloat), (GLvoid*)(3 * sizeof(GLfloat)));
	glEnableVertexAttribArray(2);

	glBindVertexArray(0); // Unbind VAO

	// Game loop
	while (!glfwWindowShouldClose(window))
	{
		// Check if any events have been activiated (key pressed, mouse moved etc.) and call corresponding response functions
		glfwPollEvents();

		// Render
		// Clear the colorbuffer
		glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

		// Activate shader
		ourShader.Use();

		// Create transformations
		glm::mat4 model(1);
		glm::mat4 view(1);
		glm::mat4 projection(1);
		model = glm::rotate(model, (GLfloat)glfwGetTime() * glm::radians(50.0f), glm::vec3(0.5f, 1.0f, 0.0f));
		view = glm::translate(view, glm::vec3(0.0f, 0.0f, -3.0f));
		// Note: currently we set the projection matrix each frame, but since the projection matrix rarely changes it's often best practice to set it outside the main loop only once.
		projection = glm::perspective(glm::radians(45.0f), (GLfloat)WIDTH / (GLfloat)HEIGHT, 0.1f, 100.0f);
		// Get their uniform location
		GLint modelLoc = glGetUniformLocation(ourShader.Program, "model");
		GLint viewLoc = glGetUniformLocation(ourShader.Program, "view");
		GLint projLoc = glGetUniformLocation(ourShader.Program, "projection");
		// Pass them to the shaders
		glUniformMatrix4fv(modelLoc, 1, GL_FALSE, glm::value_ptr(model));
		glUniformMatrix4fv(viewLoc, 1, GL_FALSE, glm::value_ptr(view));
		glUniformMatrix4fv(projLoc, 1, GL_FALSE, glm::value_ptr(projection));

		// Draw container
		glBindVertexArray(VAO);
		glDrawArrays(GL_TRIANGLES, 0, 36);
		glBindVertexArray(0);

		// Swap the screen buffers
		glfwSwapBuffers(window);
	}
	// Properly de-allocate all resources once they've outlived their purpose
	glDeleteVertexArrays(1, &VAO);
	glDeleteBuffers(1, &VBO);
	// Terminate GLFW, clearing any resources allocated by GLFW.
	glfwTerminate();
	return 0;
}

// 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);
}