Example/OpenGL Error Testing with Message Callbacks

A simple example of how to utilize debug message callbacks (e.g. for detecting OpenGL errors):

void MessageCallback( GLenum source,
                      GLenum type,
                      GLuint id,
                      GLenum severity,
                      GLsizei length,
                      const GLchar* message,
                      const void* userParam )
{
  fprintf( stderr, "GL CALLBACK: %s type = 0x%x, severity = 0x%x, message = %s\n",
           ( type == GL_DEBUG_TYPE_ERROR ? "** GL ERROR **" : "" ),
            type, severity, message );
}

// During init, enable debug output
glEnable              ( GL_DEBUG_OUTPUT );
glDebugMessageCallback( (GLDEBUGPROC) MessageCallback, 0 );