src/glut/os2/glut_swap.cpp

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