Opening a window

Ok, let’s go. First, we’ll have to deal with dependencies : we need some basic stuff to display messages in the console :

// Include standard headers
#include <stdio.h>
#include <stdlib.h>

First, GLEW. So this one actually is a little bit magic, but let’s leave this for later.

// Include GLEW. Always include it before gl.h and glfw.h, since it's a bit magic.
#include <GL/glew.h>

We decided to let GLFW handle the window and the keyboard, so let’s include it too :

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

We don’t actually need this one right now, but this is a library for 3D mathematics. It will prove very useful soon. There is no magic in GLM, you can write your own if you want; it’s just handy. The “using namespace” is there to avoid typing “glm::vec3″, but “vec3″ instead.

// Include GLM
#include <glm/glm.hpp>
using namespace glm;

If you cut’n paste all these #include’s in playground.cpp, the compiler will complain that there is no main() function. So let’s create one :

int main(){
}

First thing to do it to initialize GLFW :

// Initialise GLFW
if( !glfwInit() )
{
    fprintf( stderr, "Failed to initialize GLFW\n" );
    return -1;
}

We can now create our first OpenGL window !

glfwWindowHint(GLFW_SAMPLES, 4); // 4x antialiasing
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); // We want OpenGL 3.3
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3);
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE); // To make MacOS happy; should not be needed
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); //We don't want the old OpenGL 

// Open a window and create its OpenGL context 
GLFWwindow* window; // (In the accompanying source code, this variable is global) 
window = glfwCreateWindow( 1024, 768, "Tutorial 01", NULL, NULL); 
if( window == NULL ){
    fprintf( stderr, "Failed to open GLFW window. If you have an Intel GPU, they are not 3.3 compatible. Try the 2.1 version of the tutorials.\n" );
    glfwTerminate();
    return -1;
}
glfwMakeContextCurrent(window); // Initialize GLEW 
glewExperimental=true; // Needed in core profile 
if (glewInit() != GLEW_OK) {
    fprintf(stderr, "Failed to initialize GLEW\n");
    return -1;
}

Build this and run. A window should appear, and be closed right away. Of course ! We need to wait until the user hits the Escape key :

// Ensure we can capture the escape key being pressed below
glfwSetInputMode(window, GLFW_STICKY_KEYS, GL_TRUE);

do{
    // Draw nothing, see you in tutorial 2 !

    // Swap buffers
    glfwSwapBuffers(window);
    glfwPollEvents();

} // Check if the ESC key was pressed or the window was closed
while( glfwGetKey(window, GLFW_KEY_ESCAPE ) != GLFW_PRESS &&
glfwWindowShouldClose(window) == 0 );