glfw/docs/quick.dox

/*!

@page quick Getting started

@section quick_start Introduction

In this guide you will learn how to write simple OpenGL applications using
GLFW 3.  We start by initializing GLFW, then we create a window and read some
user keyboard input.


@section quick_include Including the GLFW header

The first thing you have to do when using GLFW is including the GLFW header.

@code
#include <GL/glfw3.h>
@endcode

This header defines all the constants, types and function prototypes of the
GLFW API.  It also includes the OpenGL header provided by your development
environment and defines all the necessary constants and types for it to work on
that particular platform.

Starting with version 3.0, the GLU header @c glu.h is no longer included by
default.  If you wish to include it, define @c GLFW_INCLUDE_GLU before the
inclusion of the GLFW header.


@section quick_init_term Initializing and terminating GLFW

Before you can use most GLFW functions, the library must be initialized.  This
is done with @ref glfwInit, which returns non-zero if successful, or zero if an
error occurred.

@code
if (!glfwInit())
{
    exit(EXIT_FAILURE);
}
@endcode

When you are done using GLFW, typically at the very end of the program, you need
to call @ref glfwTerminate.

@code
glfwTerminate();
@endcode

This destroys any remaining windows and releases any other resources allocated by
GLFW.  After this call, you must call @ref glfwInit again before using any GLFW
functions that require it.


@section quick_create_window Creating a window and context

The window (and its context) is created with @ref glfwCreateWindow, which
returns a handle to the created window.  For example, this creates an 640 by 480
pixels windowed mode window:

@code
GLFWwindow* window = glfwCreateWindow(640, 480, "My Title", NULL, NULL);
@endcode

If window creation fails, @c NULL will be returned, so you need to check whether
it did.

@code
if (!window)
{
    glfwTerminate();
    exit(EXIT_FAILURE);
}
@endcode

This handle is then passed to all window related functions, and is provided to
you along with input events, so you know which window received the input.

To create a fullscreen window, you need to specify which monitor the window
should use.  In most cases, the user's primary monitor is a good choice.  You
can get this with @ref glfwGetPrimaryMonitor.  To make the above window
fullscreen, just pass along the monitor handle:

@code
GLFWwindow* window = glfwCreateWindow(640, 480, "My Title", glfwGetPrimaryMonitor(), NULL);
@endcode

Fullscreen windows cover the entire screen, have no border or decorations, and
change the monitor's resolution to the one most closely matching the requested
window size.

When you are done with the window, destroy it with the @ref glfwDestroyWindow
function.

@code
glfwDestroyWindow(window);
@endcode

Once this function is called, no more events will be delivered for that window
and its handle becomes invalid.


@section quick_window_attribs Retrieving window attributes

Each window provides a number of attributes that can be queried with @ref
glfwGetWindowParam.  Some are related to the window itself and others to the
OpenGL context.  For example, to find out if the user is attempting to close the
window, either by pressing the close widget in the title bar or using a key
combination like Alt+F4, check the @c GLFW_SHOULD_CLOSE attribute.

@code
while (!glfwGetWindowParam(window, GLFW_SHOULD_CLOSE))
{
    // Keep running
}
@endcode


@section quick_swap_buffers Swapping buffers

GLFW windows always use double-buffering.  That means that you have two
rendering buffers; a front buffer and a back buffer.  The front buffer is the
one being displayed and the back buffer the one you render to.

When the entire frame has been rendered, it is time to swap the back and the
front buffers in order to display the rendered frame, and begin rendering a new
frame.  This is done with @ref glfwSwapBuffers.

@code
glfwSwapBuffers(window);
@endcode


@section quick_process_events Processing events

GLFW needs to communicate regularly with the window system in order to receive
events, like the ones controlling the attribute @c GLFW_SHOULD_CLOSE mentioned
above.  Event processing must be done regularly and is normally done each frame
before rendering but after buffer swap.

There are two ways to process events.  @ref glfwPollEvents processes only those
events that have already been received and then returns immediately.  This is
the best choice when rendering continually, like most games do.

@code
glfwPollEvents();
@endcode

If instead you only need to update your rendering once you have received new
input, @ref glfwWaitEvents is a better choice.  It will wait until at least one
event has been received and then process all received events before returning.

@code
glfwWaitEvents();
@endcode


@section quick_example Putting it together: A minimal GLFW application

Now that you know how to initialize GLFW, create a window and poll for
keyboard input, it's possible to create a simple program.

@code
#include <GL/glfw3.h>
#include <stdlib.h>

int main(void)
{
    GLFWwindow* window;

    if (!glfwInit())
    {
        exit(EXIT_FAILURE);
    }

    window = glfwCreateWindow(640, 480, "My Window", NULL, NULL);
    if (!window)
    {
        glfwTerminate();
        exit(EXIT_FAILURE);
    }

    while (!glfwGetWindowParam(window, GLFW_SHOULD_CLOSE))
    {
        glClear(GL_COLOR_BUFFER_BIT);
        glfwSwapBuffers(window);
        glfwPollEvents();
    }

    glfwDestroyWindow(window);

    glfwTerminate();
    exit(EXIT_SUCCESS);
}
@endcode

This program creates a 640 by 480 pixels window and runs a loop clearing the
screen and processing events until the user closes the window.

*/