src/glut/glx/glut_mesa.c

   1
   2 /* Copyright (c) Mark J. Kilgard, 1996. */
   3
   4 /* This program is freely distributable without licensing fees
   5    and is provided without guarantee or warrantee expressed or
   6    implied. This program is -not- in the public domain. */
   7
   8 #include <stdlib.h>
   9 #include <string.h>
  10 #include "glutint.h"
  11
  12 int __glutMesaSwapHackSupport = 0;  /* Not supported until
  13                                        proven otherwise. */
  14
  15 /* Use the "Mesa swap hack" if reasonable if and only if
  16    MESA_SWAP_HACK is set to something whose first character is
  17    not "N" or "n" AND "Brian Paul" is the vendor string AND
  18    "Mesa X11"* (or "Mesa" for backward compatibility)  is the
  19    renderer string.
  20
  21    Anyone who modifies Mesa so that glXSwapBuffers does not
  22    simply blit the previously rendered back buffer should
  23    change either their vendor or renderer string to avoid
  24    confusing GLUT. */
  25
  26 void
  27 __glutDetermineMesaSwapHackSupport(void)
  28 {
  29   static int doneAlready = 0;
  30   char *env, *vendor, *renderer;
  31
  32   if (doneAlready)
  33     return;
  34   env = getenv("MESA_SWAP_HACK");
  35   if (env) {
  36     if ((env[0] != 'n') && (env[0] != 'N')) {
  37       vendor = (char *) glGetString(GL_VENDOR);
  38       renderer = (char *) glGetString(GL_RENDERER);
  39
  40       /* Old versions of X11 Mesa uses the renderer string
  41          "Mesa"; Brian plans to start using "Mesa X11" to
  42          distinguish the X version of Mesa from other flavor
  43          such as Windows or 3Dfx. */
  44
  45 #define MESA_X11 "Mesa X11"
  46
  47       /* XXX At some point in the future, eliminate the
  48          backward compatibility for the old "Mesa" renderer
  49          string. */
  50
  51       if (!strcmp(vendor, "Brian Paul") && (!strcmp(renderer, "Mesa") ||
  52           !strncmp(renderer, MESA_X11, sizeof(MESA_X11) - 1)))
  53         __glutMesaSwapHackSupport = 1;
  54     }
  55   }
  56   doneAlready = 1;
  57 }