OpenGL extensions with X-macros

//----------------------------------------------------------------------
// in opengl.h
XX(PFNGLACTIVETEXTUREPROC,           glActiveTexture)
XX(PFNGLATTACHSHADERPROC,            glAttachShader)
XX(PFNGLBINDBUFFERPROC,              glBindBuffer)
// etc.

//----------------------------------------------------------------------
// in a C file
// Define all the OpenGL function pointers
#define XX(t, n) t n;
#include "opengl.h"

//----------------------------------------------------------------------
// in an init function
// Load all the OpenGL function pointers.
#define XX(t, n) (n) = (t)win_get_gl_proc_address(#n); // calls wglGetProcAddress and/or GetProcAddress
#include "opengl.h"