src/glut/glx/glut_swap.c

   1
   2 /* Copyright (c) Mark J. Kilgard, 1994, 1997.  */
   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 <stdio.h>
   9 #include "glutint.h"
  10
  11 GLint __glutFPS = 0;
  12 GLint __glutSwapCount = 0;
  13 GLint __glutSwapTime = 0;
  14
  15 /* CENTRY */
  16 void GLUTAPIENTRY
  17 glutSwapBuffers(void)
  18 {
  19   GLUTwindow *window = __glutCurrentWindow;
  20
  21   if (__glutPPMFile) {
  22      __glutWritePPMFile();
  23   }
  24
  25   if (window->renderWin == window->win) {
  26     if (__glutCurrentWindow->treatAsSingle) {
  27       /* Pretend the double buffered window is single buffered,
  28          so treat glutSwapBuffers as a no-op. */
  29       return;
  30     }
  31   } else {
  32     if (__glutCurrentWindow->overlay->treatAsSingle) {
  33       /* Pretend the double buffered overlay is single
  34          buffered, so treat glutSwapBuffers as a no-op. */
  35       return;
  36     }
  37   }
  38
  39   /* For the MESA_SWAP_HACK. */
  40   window->usedSwapBuffers = 1;
  41
  42   SWAP_BUFFERS_LAYER(__glutCurrentWindow);
  43
  44   /* I considered putting the window being swapped on the
  45      GLUT_FINISH_WORK work list because you could call
  46      glutSwapBuffers from an idle callback which doesn't call
  47      __glutSetWindow which normally adds indirect rendering
  48      windows to the GLUT_FINISH_WORK work list.  Not being put
  49      on the list could lead to the buffering up of multiple
  50      redisplays and buffer swaps and hamper interactivity.  I
  51      consider this an application bug due to not using
  52      glutPostRedisplay to trigger redraws.  If
  53      glutPostRedisplay were used, __glutSetWindow would be
  54      called and a glFinish to throttle buffering would occur. */
  55
  56   if (__glutFPS) {
  57      GLint t = glutGet(GLUT_ELAPSED_TIME);
  58      __glutSwapCount++;
  59      if (__glutSwapTime == 0)
  60         __glutSwapTime = t;
  61      else if (t - __glutSwapTime > __glutFPS) {
  62         float time = 0.001 * (t - __glutSwapTime);
  63         float fps = (float) __glutSwapCount / time;
  64         fprintf(stderr, "GLUT: %d frames in %.2f seconds = %.2f FPS\n",
  65                 __glutSwapCount, time, fps);
  66         __glutSwapTime = t;
  67         __glutSwapCount = 0;
  68      }
  69   }
  70 }
  71 /* ENDCENTRY */