======================================== gl3w: Simple OpenGL core profile loading

Introduction

gl3w_ is the easiest way to get your hands on the functionality offered by the OpenGL core profile specification.

Its main part is a simple gl3w_gen.py_ Python script that downloads the Khronos_ supported glcorearb.h_ header and generates gl3w.h and gl3w.c from it. Those files can then be added and linked (statically or dynamically) into your project.

Requirements

gl3w_gen.py_ requires Python version 2.7 or newer. It is also compatible with Python 3.x.

Example

Here is a simple example of using gl3w_ with glut. Note that GL/gl3w.h must be included before any other OpenGL related headers::

#include <stdio.h>
#include <GL/gl3w.h>
#include <GL/glut.h>

// ...

int main(int argc, char **argv)
{
        glutInit(&argc, argv);
        glutInitDisplayMode(GLUT_RGBA | GLUT_DEPTH | GLUT_DOUBLE);
        glutInitWindowSize(width, height);
        glutCreateWindow("cookie");

        glutReshapeFunc(reshape);
        glutDisplayFunc(display);
        glutKeyboardFunc(keyboard);
        glutSpecialFunc(special);
        glutMouseFunc(mouse);
        glutMotionFunc(motion);

        if (gl3wInit()) {
                fprintf(stderr, "failed to initialize OpenGL\n");
                return -1;
        }
        if (!gl3wIsSupported(3, 2)) {
                fprintf(stderr, "OpenGL 3.2 not supported\n");
                return -1;
        }
        printf("OpenGL %s, GLSL %s\n", glGetString(GL_VERSION),
               glGetString(GL_SHADING_LANGUAGE_VERSION));

        // ...

        glutMainLoop();
        return 0;
}

If your Project is using CMake you can import gl3w_ using FetchContent::

include(FetchContent)
FetchContent_Declare(
    gl3w
    GIT_REPOSITORY https://github.com/skaslev/gl3w.git
    GIT_TAG        master
    GIT_SHALLOW    TRUE
    GIT_PROGRESS   TRUE
    EXCLUDE_FROM_ALL
)
FetchContent_MakeAvailable(gl3w)
# Declare your target that needs gl3w here
target_link_libraries(<target> PRIVATE gl3w)

API Reference

The gl3w_ API consists of just three functions:

int gl3wInit(void)

Initializes the library. Should be called once after an OpenGL context has
been created. Returns ``0`` when gl3w_ was initialized successfully,
``non-zero`` if there was an error.

int gl3wIsSupported(int major, int minor)

Returns ``1`` when OpenGL core profile version *major.minor* is available
and ``0`` otherwise.

GL3WglProc gl3wGetProcAddress(const char *proc)

Returns the address of an OpenGL extension function. Generally, you won't
need to use it since gl3w_ loads all functions defined in the OpenGL core
profile on initialization. It allows you to load OpenGL extensions outside
of the core profile.

Options

The generator script optionally takes the arguments:

--ext to include the GL Extensions in output header.

--root=outputdir to set the location for the output to something else than current working directory.

License

.. image:: public-domain-mark.png

gl3w_ is in the public domain. See the file UNLICENSE for more information.

Credits

Slavomir Kaslev slavomir.kaslev@gmail.com Initial implementation

Kelvin McDowell Mac OS X support

Sjors Gielen Mac OS X support

Travis Gesslein Patches regarding glcorearb.h

Arthur Tombs Port to Python 3

Daniel Cousens [https://github.com/dcousens] Code contributions

Copyright

OpenGL_ is a registered trademark of SGI_.

.. _gl3w: https://github.com/skaslev/gl3w .. _gl3w_gen.py: https://github.com/skaslev/gl3w/blob/master/gl3w_gen.py .. _glcorearb.h: https://www.opengl.org/registry/api/GL/glcorearb.h .. _OpenGL: http://www.opengl.org/ .. _Khronos: http://www.khronos.org/ .. _SGI: http://www.sgi.com/