
/* Copyright (c) Mark J. Kilgard, 1994. */

/* This program is freely distributable without licensing fees
   and is provided without guarantee or warrantee expressed or
   implied. This program is -not- in the public domain. */

#include <string.h>

#include <GL/glut.h>
#include "glutint.h"

int
glutExtensionSupported(char *extension)
{
  static const GLubyte *extensions = NULL;
  const GLubyte *start;
  GLubyte *where, *terminator;

  /* Extension names should not have spaces. */
  where = (GLubyte *) strchr(extension, ' ');
  if (where || *extension == '\0')
    return 0;

  if (!extensions)
    extensions = glGetString(GL_EXTENSIONS);
  /* It takes a bit of care to be fool-proof about parsing the
     OpenGL extensions string.  Don't be fooled by sub-strings, 
     etc. */
  start = extensions;
  for (;;) {
    where = (GLubyte *) strstr((const char *)start, extension);
    if (!where)
      break;
    terminator = where + strlen(extension);
    if (where == start || *(where - 1) == ' ') {
      if (*terminator == ' ' || *terminator == '\0') {
        return 1;
      }
    }
    start = terminator;
  }
  return 0;
}

int
__glutIsSupportedByGLX(char *extension)
{
#if defined(GLX_VERSION_1_1)
  static const char *extensions = NULL;
  const char *start;
  char *where, *terminator;
  int major, minor;

  glXQueryVersion(__glutDisplay, &major, &minor);
  /* Be careful not to call glXQueryExtensionsString if it
     looks like the server doesn't support GLX 1.1.
     Unfortunately, the original GLX 1.0 didn't have the notion 
     of GLX extensions. */
  if ((major == 1 && minor >= 1) || (major > 1)) {
    if (!extensions)
      extensions = glXQueryExtensionsString(__glutDisplay, __glutScreen);
    /* It takes a bit of care to be fool-proof about parsing
       the GLX extensions string.  Don't be fooled by
       sub-strings,  etc. */
    start = extensions;
    for (;;) {
      where = strstr(start, extension);
      if (!where)
        return 0;
      terminator = where + strlen(extension);
      if (where == start || *(where - 1) == ' ') {
        if (*terminator == ' ' || *terminator == '\0') {
          return 1;
        }
      }
      start = terminator;
    }
  }
#else
  /* No GLX extensions before GLX 1.1 */
#endif
  return 0;
}

