gl3w: Simple OpenGL core profile loading

ROS wrapper

This fork adds compatibility to compile it as part of a catkin workspace. A package.xml has been added and the CMakeLists.txt has been modified to be relocatable.

To use this library in your ROS package add:

A dependency on gl3w to your package.xml
find_package(gl3w REQUIRED) and catkin_package(... DEPENDS gl3w) to your CMakeLists.txt

An example package for using this library is scigl_render_ros.

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;
}

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.

License

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.

Tuebel/gl3w_ros