#include <iostream>  
 
// GLEW  
#define GLEW_STATIC  
#include <GL/glew.h>  
 
// GLFW  
#include <GLFW/glfw3.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()
{
    std::cout << "Starting GLFW context, OpenGL 3.3" << std::endl;
    // Init GLFW  
    glfwInit();
    // Set all the required options for GLFW  
    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);
 
    // Create a GLFWwindow object that we can use for GLFW‘s functions  
    GLFWwindow* window = glfwCreateWindow(WIDTH, HEIGHT, "LearnOpenGL", nullptr, nullptr);
    if (window == nullptr)
    {
        std::cout << "Failed to create GLFW window" << std::endl;
        glfwTerminate();
        return -1;
    }
    glfwMakeContextCurrent(window);
    // Set the required callback functions  
    glfwSetKeyCallback(window, key_callback);
 
    // Set this to true so GLEW knows to use a modern approach to retrieving function pointers and extensions  
    glewExperimental = GL_TRUE;
    // Initialize GLEW to setup the OpenGL Function pointers  
    if (glewInit() != GLEW_OK)
    {
        std::cout << "Failed to initialize GLEW" << std::endl;
        return -1;
    }
 
    // Define the viewport dimensions  
    glViewport(0, 0, WIDTH, HEIGHT);
 
    // 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);
 
        // Swap the screen buffers  
        glfwSwapBuffers(window);
    }
 
    // 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)
{
    std::cout << key << std::endl;
    if (key == GLFW_KEY_ESCAPE && action == GLFW_PRESS)
        glfwSetWindowShouldClose(window, GL_TRUE);
}