glxswapcontrol.c revision 32001f49 
1/*
2 * Copyright (C) 1999-2001  Brian Paul   All Rights Reserved.
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice shall be included
12 * in all copies or substantial portions of the Software.
13 *
14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
15 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
17 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
18 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
19 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
20 */
21
22/*
23 * This is a port of the infamous "gears" demo to straight GLX (i.e. no GLUT)
24 * Port by Brian Paul  23 March 2001
25 *
26 * Modified by Ian Romanick <idr@us.ibm.com> 09 April 2003 to support
27 * GLX_{MESA,SGI}_swap_control and GLX_OML_sync_control.
28 *
29 * Command line options:
30 *    -display       Name of the display to use.
31 *    -info          print GL implementation information
32 *    -swap N        Attempt to set the swap interval to 1/N second
33 *    -forcegetrate  Get the display refresh rate even if the required GLX
34 *                   extension is not supported.
35 */
36
37
38#include <math.h>
39#include <stdlib.h>
40#include <stdio.h>
41#include <string.h>
42#include <X11/Xlib.h>
43#include <X11/keysym.h>
44#ifndef __VMS
45/*# include <stdint.h>*/
46#endif
47# define GLX_GLXEXT_PROTOTYPES
48#include <GL/gl.h>
49#include <GL/glx.h>
50
51#ifndef GLX_MESA_swap_control
52typedef GLint ( * PFNGLXSWAPINTERVALMESAPROC) (unsigned interval);
53typedef GLint ( * PFNGLXGETSWAPINTERVALMESAPROC) ( void );
54#endif
55
56#if !defined( GLX_OML_sync_control ) && defined( _STDINT_H )
57#define GLX_OML_sync_control 1
58typedef Bool ( * PFNGLXGETMSCRATEOMLPROC) (Display *dpy, GLXDrawable drawable, int32_t *numerator, int32_t *denominator);
59#endif
60
61#ifndef GLX_MESA_swap_frame_usage
62#define GLX_MESA_swap_frame_usage 1
63typedef int ( * PFNGLXGETFRAMEUSAGEMESAPROC) (Display *dpy, GLXDrawable drawable, float * usage );
64#endif
65
66#define BENCHMARK
67
68PFNGLXGETFRAMEUSAGEMESAPROC get_frame_usage = NULL;
69
70#ifdef BENCHMARK
71
72/* XXX this probably isn't very portable */
73
74#include <sys/time.h>
75#include <unistd.h>
76
77#define NUL '\0'
78
79/* return current time (in seconds) */
80static int
81current_time(void)
82{
83   struct timeval tv;
84#ifdef __VMS
85   (void) gettimeofday(&tv, NULL );
86#else
87   struct timezone tz;
88   (void) gettimeofday(&tv, &tz);
89#endif
90   return (int) tv.tv_sec;
91}
92
93#else /*BENCHMARK*/
94
95/* dummy */
96static int
97current_time(void)
98{
99   return 0;
100}
101
102#endif /*BENCHMARK*/
103
104
105
106#ifndef M_PI
107#define M_PI 3.14159265
108#endif
109
110
111static GLfloat view_rotx = 20.0, view_roty = 30.0, view_rotz = 0.0;
112static GLint gear1, gear2, gear3;
113static GLfloat angle = 0.0;
114
115static GLboolean has_OML_sync_control = GL_FALSE;
116static GLboolean has_SGI_swap_control = GL_FALSE;
117static GLboolean has_MESA_swap_control = GL_FALSE;
118static GLboolean has_MESA_swap_frame_usage = GL_FALSE;
119
120static char ** extension_table = NULL;
121static unsigned num_extensions;
122
123static GLboolean use_ztrick = GL_FALSE;
124static GLfloat aspectX = 1.0f, aspectY = 1.0f;
125
126/*
127 *
128 *  Draw a gear wheel.  You'll probably want to call this function when
129 *  building a display list since we do a lot of trig here.
130 *
131 *  Input:  inner_radius - radius of hole at center
132 *          outer_radius - radius at center of teeth
133 *          width - width of gear
134 *          teeth - number of teeth
135 *          tooth_depth - depth of tooth
136 */
137static void
138gear(GLfloat inner_radius, GLfloat outer_radius, GLfloat width,
139     GLint teeth, GLfloat tooth_depth)
140{
141   GLint i;
142   GLfloat r0, r1, r2;
143   GLfloat angle, da;
144   GLfloat u, v, len;
145
146   r0 = inner_radius;
147   r1 = outer_radius - tooth_depth / 2.0;
148   r2 = outer_radius + tooth_depth / 2.0;
149
150   da = 2.0 * M_PI / teeth / 4.0;
151
152   glShadeModel(GL_FLAT);
153
154   glNormal3f(0.0, 0.0, 1.0);
155
156   /* draw front face */
157   glBegin(GL_QUAD_STRIP);
158   for (i = 0; i <= teeth; i++) {
159      angle = i * 2.0 * M_PI / teeth;
160      glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
161      glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
162      if (i < teeth) {
163	 glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
164	 glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da),
165		    width * 0.5);
166      }
167   }
168   glEnd();
169
170   /* draw front sides of teeth */
171   glBegin(GL_QUADS);
172   da = 2.0 * M_PI / teeth / 4.0;
173   for (i = 0; i < teeth; i++) {
174      angle = i * 2.0 * M_PI / teeth;
175
176      glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
177      glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
178      glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da),
179		 width * 0.5);
180      glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da),
181		 width * 0.5);
182   }
183   glEnd();
184
185   glNormal3f(0.0, 0.0, -1.0);
186
187   /* draw back face */
188   glBegin(GL_QUAD_STRIP);
189   for (i = 0; i <= teeth; i++) {
190      angle = i * 2.0 * M_PI / teeth;
191      glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
192      glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
193      if (i < teeth) {
194	 glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da),
195		    -width * 0.5);
196	 glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
197      }
198   }
199   glEnd();
200
201   /* draw back sides of teeth */
202   glBegin(GL_QUADS);
203   da = 2.0 * M_PI / teeth / 4.0;
204   for (i = 0; i < teeth; i++) {
205      angle = i * 2.0 * M_PI / teeth;
206
207      glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da),
208		 -width * 0.5);
209      glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da),
210		 -width * 0.5);
211      glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
212      glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
213   }
214   glEnd();
215
216   /* draw outward faces of teeth */
217   glBegin(GL_QUAD_STRIP);
218   for (i = 0; i < teeth; i++) {
219      angle = i * 2.0 * M_PI / teeth;
220
221      glVertex3f(r1 * cos(angle), r1 * sin(angle), width * 0.5);
222      glVertex3f(r1 * cos(angle), r1 * sin(angle), -width * 0.5);
223      u = r2 * cos(angle + da) - r1 * cos(angle);
224      v = r2 * sin(angle + da) - r1 * sin(angle);
225      len = sqrt(u * u + v * v);
226      u /= len;
227      v /= len;
228      glNormal3f(v, -u, 0.0);
229      glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), width * 0.5);
230      glVertex3f(r2 * cos(angle + da), r2 * sin(angle + da), -width * 0.5);
231      glNormal3f(cos(angle), sin(angle), 0.0);
232      glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da),
233		 width * 0.5);
234      glVertex3f(r2 * cos(angle + 2 * da), r2 * sin(angle + 2 * da),
235		 -width * 0.5);
236      u = r1 * cos(angle + 3 * da) - r2 * cos(angle + 2 * da);
237      v = r1 * sin(angle + 3 * da) - r2 * sin(angle + 2 * da);
238      glNormal3f(v, -u, 0.0);
239      glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da),
240		 width * 0.5);
241      glVertex3f(r1 * cos(angle + 3 * da), r1 * sin(angle + 3 * da),
242		 -width * 0.5);
243      glNormal3f(cos(angle), sin(angle), 0.0);
244   }
245
246   glVertex3f(r1 * cos(0), r1 * sin(0), width * 0.5);
247   glVertex3f(r1 * cos(0), r1 * sin(0), -width * 0.5);
248
249   glEnd();
250
251   glShadeModel(GL_SMOOTH);
252
253   /* draw inside radius cylinder */
254   glBegin(GL_QUAD_STRIP);
255   for (i = 0; i <= teeth; i++) {
256      angle = i * 2.0 * M_PI / teeth;
257      glNormal3f(-cos(angle), -sin(angle), 0.0);
258      glVertex3f(r0 * cos(angle), r0 * sin(angle), -width * 0.5);
259      glVertex3f(r0 * cos(angle), r0 * sin(angle), width * 0.5);
260   }
261   glEnd();
262}
263
264
265static void
266draw(void)
267{
268   if ( use_ztrick ) {
269      static GLboolean flip = GL_FALSE;
270      static const GLfloat vert[4][3] = {
271	 { -1, -1, -0.999 },
272	 {  1, -1, -0.999 },
273	 {  1,  1, -0.999 },
274	 { -1,  1, -0.999 }
275      };
276      static const GLfloat col[4][3] = {
277	 { 1.0, 0.6, 0.0 },
278	 { 1.0, 0.6, 0.0 },
279	 { 0.0, 0.0, 0.0 },
280	 { 0.0, 0.0, 0.0 },
281      };
282
283      if ( flip ) {
284	 glDepthRange(0, 0.5);
285	 glDepthFunc(GL_LEQUAL);
286      }
287      else {
288	 glDepthRange(1.0, 0.4999);
289	 glDepthFunc(GL_GEQUAL);
290      }
291
292      flip = !flip;
293
294      /* The famous Quake "Z trick" only works when the whole screen is
295       * re-drawn each frame.
296       */
297
298      glMatrixMode(GL_MODELVIEW);
299      glLoadIdentity();
300      glMatrixMode(GL_PROJECTION);
301      glLoadIdentity();
302      glOrtho(-1, 1, -1, 1, -1, 1);
303      glDisable(GL_LIGHTING);
304      glShadeModel(GL_SMOOTH);
305
306      glEnableClientState( GL_VERTEX_ARRAY );
307      glEnableClientState( GL_COLOR_ARRAY );
308      glVertexPointer( 3, GL_FLOAT, 0, vert );
309      glColorPointer( 3, GL_FLOAT, 0, col );
310      glDrawArrays( GL_POLYGON, 0, 4 );
311      glDisableClientState( GL_COLOR_ARRAY );
312      glDisableClientState( GL_VERTEX_ARRAY );
313
314      glMatrixMode(GL_PROJECTION);
315      glLoadIdentity();
316      glFrustum(-aspectX, aspectX, -aspectY, aspectY, 5.0, 60.0);
317
318      glEnable(GL_LIGHTING);
319
320      glMatrixMode(GL_MODELVIEW);
321      glLoadIdentity();
322      glTranslatef(0.0, 0.0, -45.0);
323   }
324   else {
325      glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
326   }
327
328   glPushMatrix();
329   glRotatef(view_rotx, 1.0, 0.0, 0.0);
330   glRotatef(view_roty, 0.0, 1.0, 0.0);
331   glRotatef(view_rotz, 0.0, 0.0, 1.0);
332
333   glPushMatrix();
334   glTranslatef(-3.0, -2.0, 0.0);
335   glRotatef(angle, 0.0, 0.0, 1.0);
336   glCallList(gear1);
337   glPopMatrix();
338
339   glPushMatrix();
340   glTranslatef(3.1, -2.0, 0.0);
341   glRotatef(-2.0 * angle - 9.0, 0.0, 0.0, 1.0);
342   glCallList(gear2);
343   glPopMatrix();
344
345   glPushMatrix();
346   glTranslatef(-3.1, 4.2, 0.0);
347   glRotatef(-2.0 * angle - 25.0, 0.0, 0.0, 1.0);
348   glCallList(gear3);
349   glPopMatrix();
350
351   glPopMatrix();
352}
353
354
355/* new window size or exposure */
356static void
357reshape(int width, int height)
358{
359   if (width > height) {
360      aspectX = (GLfloat) width / (GLfloat) height;
361      aspectY = 1.0;
362   }
363   else {
364      aspectX = 1.0;
365      aspectY = (GLfloat) height / (GLfloat) width;
366   }
367
368   glViewport(0, 0, (GLint) width, (GLint) height);
369   glMatrixMode(GL_PROJECTION);
370   glLoadIdentity();
371
372   glFrustum(-aspectX, aspectX, -aspectY, aspectY, 5.0, 60.0);
373   glMatrixMode(GL_MODELVIEW);
374   glLoadIdentity();
375   glTranslatef(0.0, 0.0, -45.0);
376}
377
378
379static void
380init(void)
381{
382   static GLfloat pos[4] = { 5.0, 5.0, 10.0, 0.0 };
383   static GLfloat red[4] = { 0.8, 0.1, 0.0, 1.0 };
384   static GLfloat green[4] = { 0.0, 0.8, 0.2, 1.0 };
385   static GLfloat blue[4] = { 0.2, 0.2, 1.0, 1.0 };
386
387   glLightfv(GL_LIGHT0, GL_POSITION, pos);
388   glEnable(GL_CULL_FACE);
389   glEnable(GL_LIGHTING);
390   glEnable(GL_LIGHT0);
391   glEnable(GL_DEPTH_TEST);
392
393   /* make the gears */
394   gear1 = glGenLists(1);
395   glNewList(gear1, GL_COMPILE);
396   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, red);
397   gear(1.0, 4.0, 1.0, 20, 0.7);
398   glEndList();
399
400   gear2 = glGenLists(1);
401   glNewList(gear2, GL_COMPILE);
402   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, green);
403   gear(0.5, 2.0, 2.0, 10, 0.7);
404   glEndList();
405
406   gear3 = glGenLists(1);
407   glNewList(gear3, GL_COMPILE);
408   glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, blue);
409   gear(1.3, 2.0, 0.5, 10, 0.7);
410   glEndList();
411
412   glEnable(GL_NORMALIZE);
413}
414
415
416/**
417 * Remove window border/decorations.
418 */
419static void
420no_border( Display *dpy, Window w)
421{
422   static const unsigned MWM_HINTS_DECORATIONS = (1 << 1);
423   static const int PROP_MOTIF_WM_HINTS_ELEMENTS = 5;
424
425   typedef struct
426   {
427      unsigned long       flags;
428      unsigned long       functions;
429      unsigned long       decorations;
430      long                inputMode;
431      unsigned long       status;
432   } PropMotifWmHints;
433
434   PropMotifWmHints motif_hints;
435   Atom prop, proptype;
436   unsigned long flags = 0;
437
438   /* setup the property */
439   motif_hints.flags = MWM_HINTS_DECORATIONS;
440   motif_hints.decorations = flags;
441
442   /* get the atom for the property */
443   prop = XInternAtom( dpy, "_MOTIF_WM_HINTS", True );
444   if (!prop) {
445      /* something went wrong! */
446      return;
447   }
448
449   /* not sure this is correct, seems to work, XA_WM_HINTS didn't work */
450   proptype = prop;
451
452   XChangeProperty( dpy, w,                         /* display, window */
453                    prop, proptype,                 /* property, type */
454                    32,                             /* format: 32-bit datums */
455                    PropModeReplace,                /* mode */
456                    (unsigned char *) &motif_hints, /* data */
457                    PROP_MOTIF_WM_HINTS_ELEMENTS    /* nelements */
458                  );
459}
460
461
462/*
463 * Create an RGB, double-buffered window.
464 * Return the window and context handles.
465 */
466static void
467make_window( Display *dpy, const char *name,
468             int x, int y, int width, int height, GLboolean fullscreen,
469             Window *winRet, GLXContext *ctxRet)
470{
471   int attrib[] = { GLX_RGBA,
472		    GLX_RED_SIZE, 1,
473		    GLX_GREEN_SIZE, 1,
474		    GLX_BLUE_SIZE, 1,
475		    GLX_DOUBLEBUFFER,
476		    GLX_DEPTH_SIZE, 1,
477		    None };
478   int scrnum;
479   XSetWindowAttributes attr;
480   unsigned long mask;
481   Window root;
482   Window win;
483   GLXContext ctx;
484   XVisualInfo *visinfo;
485
486   scrnum = DefaultScreen( dpy );
487   root = RootWindow( dpy, scrnum );
488
489   if (fullscreen) {
490      x = y = 0;
491      width = DisplayWidth( dpy, scrnum );
492      height = DisplayHeight( dpy, scrnum );
493   }
494
495   visinfo = glXChooseVisual( dpy, scrnum, attrib );
496   if (!visinfo) {
497      printf("Error: couldn't get an RGB, Double-buffered visual\n");
498      exit(1);
499   }
500
501   /* window attributes */
502   attr.background_pixel = 0;
503   attr.border_pixel = 0;
504   attr.colormap = XCreateColormap( dpy, root, visinfo->visual, AllocNone);
505   attr.event_mask = StructureNotifyMask | ExposureMask | KeyPressMask;
506   mask = CWBackPixel | CWBorderPixel | CWColormap | CWEventMask;
507
508   win = XCreateWindow( dpy, root, 0, 0, width, height,
509		        0, visinfo->depth, InputOutput,
510		        visinfo->visual, mask, &attr );
511
512   /* set hints and properties */
513   {
514      XSizeHints sizehints;
515      sizehints.x = x;
516      sizehints.y = y;
517      sizehints.width  = width;
518      sizehints.height = height;
519      sizehints.flags = USSize | USPosition;
520      XSetNormalHints(dpy, win, &sizehints);
521      XSetStandardProperties(dpy, win, name, name,
522                              None, (char **)NULL, 0, &sizehints);
523   }
524
525   if (fullscreen)
526      no_border(dpy, win);
527
528   ctx = glXCreateContext( dpy, visinfo, NULL, True );
529   if (!ctx) {
530      printf("Error: glXCreateContext failed\n");
531      exit(1);
532   }
533
534   XFree(visinfo);
535
536   *winRet = win;
537   *ctxRet = ctx;
538}
539
540
541static void
542event_loop(Display *dpy, Window win)
543{
544   float  frame_usage = 0.0;
545
546   while (1) {
547      while (XPending(dpy) > 0) {
548         XEvent event;
549         XNextEvent(dpy, &event);
550         switch (event.type) {
551	 case Expose:
552            /* we'll redraw below */
553	    break;
554	 case ConfigureNotify:
555	    reshape(event.xconfigure.width, event.xconfigure.height);
556	    break;
557         case KeyPress:
558            {
559               char buffer[10];
560               int code;
561               code = XLookupKeysym(&event.xkey, 0);
562               if (code == XK_Left) {
563                  view_roty += 5.0;
564               }
565               else if (code == XK_Right) {
566                  view_roty -= 5.0;
567               }
568               else if (code == XK_Up) {
569                  view_rotx += 5.0;
570               }
571               else if (code == XK_Down) {
572                  view_rotx -= 5.0;
573               }
574               else {
575                  XLookupString(&event.xkey, buffer, sizeof(buffer),
576                                NULL, NULL);
577                  if (buffer[0] == 27) {
578                     /* escape */
579                     return;
580                  }
581               }
582            }
583         }
584      }
585
586      /* next frame */
587      angle += 2.0;
588
589      draw();
590
591      glXSwapBuffers(dpy, win);
592
593      if ( get_frame_usage != NULL ) {
594	 GLfloat   temp;
595
596	 (*get_frame_usage)( dpy, win, & temp );
597	 frame_usage += temp;
598      }
599
600      /* calc framerate */
601      {
602         static int t0 = -1;
603         static int frames = 0;
604         int t = current_time();
605
606         if (t0 < 0)
607            t0 = t;
608
609         frames++;
610
611         if (t - t0 >= 5.0) {
612            GLfloat seconds = t - t0;
613            GLfloat fps = frames / seconds;
614	    if ( get_frame_usage != NULL ) {
615	       printf("%d frames in %3.1f seconds = %6.3f FPS (%3.1f%% usage)\n",
616		      frames, seconds, fps,
617		      (frame_usage * 100.0) / (float) frames );
618	    }
619	    else {
620	       printf("%d frames in %3.1f seconds = %6.3f FPS\n",
621		      frames, seconds, fps);
622	    }
623	    fflush(stdout);
624
625            t0 = t;
626            frames = 0;
627	    frame_usage = 0.0;
628         }
629      }
630   }
631}
632
633
634/**
635 * Display the refresh rate of the display using the GLX_OML_sync_control
636 * extension.
637 */
638static void
639show_refresh_rate( Display * dpy )
640{
641#if defined(GLX_OML_sync_control) && defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L)
642   PFNGLXGETMSCRATEOMLPROC  get_msc_rate;
643   int32_t  n;
644   int32_t  d;
645
646   get_msc_rate = (PFNGLXGETMSCRATEOMLPROC) glXGetProcAddressARB( (const GLubyte *) "glXGetMscRateOML" );
647   if ( get_msc_rate != NULL ) {
648      (*get_msc_rate)( dpy, glXGetCurrentDrawable(), &n, &d );
649      printf( "refresh rate: %.1fHz\n", (float) n / d );
650      return;
651   }
652#endif
653   printf( "glXGetMscRateOML not supported.\n" );
654}
655
656
657/**
658 * Fill in the table of extension strings from a supplied extensions string
659 * (as returned by glXQueryExtensionsString).
660 *
661 * \param string   String of GLX extensions.
662 * \sa is_extension_supported
663 */
664static void
665make_extension_table( const char * string )
666{
667   char ** string_tab;
668   unsigned  num_strings;
669   unsigned  base;
670   unsigned  idx;
671   unsigned  i;
672
673   /* Count the number of spaces in the string.  That gives a base-line
674    * figure for the number of extension in the string.
675    */
676
677   num_strings = 1;
678   for ( i = 0 ; string[i] != NUL ; i++ ) {
679      if ( string[i] == ' ' ) {
680	 num_strings++;
681      }
682   }
683
684   string_tab = (char **) malloc( sizeof( char * ) * num_strings );
685   if ( string_tab == NULL ) {
686      return;
687   }
688
689   base = 0;
690   idx = 0;
691
692   while ( string[ base ] != NUL ) {
693      /* Determine the length of the next extension string.
694       */
695
696      for ( i = 0
697	    ; (string[ base + i ] != NUL) && (string[ base + i ] != ' ')
698	    ; i++ ) {
699	 /* empty */ ;
700      }
701
702      if ( i > 0 ) {
703	 /* If the string was non-zero length, add it to the table.  We
704	  * can get zero length strings if there is a space at the end of
705	  * the string or if there are two (or more) spaces next to each
706	  * other in the string.
707	  */
708
709	 string_tab[ idx ] = malloc( sizeof( char ) * (i + 1) );
710	 if ( string_tab[ idx ] == NULL ) {
711            unsigned j = 0;
712
713            for ( j = 0; j < idx; j++ ) {
714               free( string_tab[j] );
715            }
716
717            free( string_tab );
718
719	    return;
720	 }
721
722	 (void) memcpy( string_tab[ idx ], & string[ base ], i );
723	 string_tab[ idx ][i] = NUL;
724	 idx++;
725      }
726
727
728      /* Skip to the start of the next extension string.
729       */
730
731      for ( base += i
732	    ; (string[ base ] == ' ') && (string[ base ] != NUL)
733	    ; base++ ) {
734	 /* empty */ ;
735      }
736   }
737
738   extension_table = string_tab;
739   num_extensions = idx;
740}
741
742
743/**
744 * Determine of an extension is supported.  The extension string table
745 * must have already be initialized by calling \c make_extension_table.
746 *
747 * \praram ext  Extension to be tested.
748 * \return GL_TRUE of the extension is supported, GL_FALSE otherwise.
749 * \sa make_extension_table
750 */
751static GLboolean
752is_extension_supported( const char * ext )
753{
754   unsigned   i;
755
756   for ( i = 0 ; i < num_extensions ; i++ ) {
757      if ( strcmp( ext, extension_table[i] ) == 0 ) {
758	 return GL_TRUE;
759      }
760   }
761
762   return GL_FALSE;
763}
764
765
766int
767main(int argc, char *argv[])
768{
769   Display *dpy;
770   Window win;
771   GLXContext ctx;
772   char *dpyName = NULL;
773   int swap_interval = 1;
774   GLboolean do_swap_interval = GL_FALSE;
775   GLboolean force_get_rate = GL_FALSE;
776   GLboolean fullscreen = GL_FALSE;
777   GLboolean printInfo = GL_FALSE;
778   int i;
779   PFNGLXSWAPINTERVALMESAPROC set_swap_interval = NULL;
780   PFNGLXGETSWAPINTERVALMESAPROC get_swap_interval = NULL;
781   int width = 300, height = 300;
782
783   for (i = 1; i < argc; i++) {
784      if (strcmp(argv[i], "-display") == 0 && i + 1 < argc) {
785         dpyName = argv[i+1];
786         i++;
787      }
788      else if (strcmp(argv[i], "-info") == 0) {
789         printInfo = GL_TRUE;
790      }
791      else if (strcmp(argv[i], "-swap") == 0 && i + 1 < argc) {
792	 swap_interval = atoi( argv[i+1] );
793	 do_swap_interval = GL_TRUE;
794	 i++;
795      }
796      else if (strcmp(argv[i], "-forcegetrate") == 0) {
797	 /* This option was put in because some DRI drivers don't support the
798	  * full GLX_OML_sync_control extension, but they do support
799	  * glXGetMscRateOML.
800	  */
801	 force_get_rate = GL_TRUE;
802      }
803      else if (strcmp(argv[i], "-fullscreen") == 0) {
804         fullscreen = GL_TRUE;
805      }
806      else if (strcmp(argv[i], "-ztrick") == 0) {
807	 use_ztrick = GL_TRUE;
808      }
809      else if (strcmp(argv[i], "-help") == 0) {
810         printf("Usage:\n");
811         printf("  gears [options]\n");
812         printf("Options:\n");
813         printf("  -help                   Print this information\n");
814         printf("  -display displayName    Specify X display\n");
815         printf("  -info                   Display GL information\n");
816         printf("  -swap N                 Swap no more than once per N vertical refreshes\n");
817         printf("  -forcegetrate           Try to use glXGetMscRateOML function\n");
818         printf("  -fullscreen             Full-screen window\n");
819         return 0;
820      }
821   }
822
823   dpy = XOpenDisplay(dpyName);
824   if (!dpy) {
825      printf("Error: couldn't open display %s\n", XDisplayName(dpyName));
826      return -1;
827   }
828
829   make_window(dpy, "glxgears", 0, 0, width, height, fullscreen, &win, &ctx);
830   XMapWindow(dpy, win);
831   glXMakeCurrent(dpy, win, ctx);
832
833   make_extension_table( (char *) glXQueryExtensionsString(dpy,DefaultScreen(dpy)) );
834   has_OML_sync_control = is_extension_supported( "GLX_OML_sync_control" );
835   has_SGI_swap_control = is_extension_supported( "GLX_SGI_swap_control" );
836   has_MESA_swap_control = is_extension_supported( "GLX_MESA_swap_control" );
837   has_MESA_swap_frame_usage = is_extension_supported( "GLX_MESA_swap_frame_usage" );
838
839   if ( has_MESA_swap_control ) {
840      set_swap_interval = (PFNGLXSWAPINTERVALMESAPROC) glXGetProcAddressARB( (const GLubyte *) "glXSwapIntervalMESA" );
841      get_swap_interval = (PFNGLXGETSWAPINTERVALMESAPROC) glXGetProcAddressARB( (const GLubyte *) "glXGetSwapIntervalMESA" );
842   }
843   else if ( has_SGI_swap_control ) {
844      set_swap_interval = (PFNGLXSWAPINTERVALMESAPROC) glXGetProcAddressARB( (const GLubyte *) "glXSwapIntervalSGI" );
845   }
846
847
848   if ( has_MESA_swap_frame_usage ) {
849      get_frame_usage = (PFNGLXGETFRAMEUSAGEMESAPROC)  glXGetProcAddressARB( (const GLubyte *) "glXGetFrameUsageMESA" );
850   }
851
852
853   if (printInfo) {
854      printf("GL_RENDERER   = %s\n", (char *) glGetString(GL_RENDERER));
855      printf("GL_VERSION    = %s\n", (char *) glGetString(GL_VERSION));
856      printf("GL_VENDOR     = %s\n", (char *) glGetString(GL_VENDOR));
857      printf("GL_EXTENSIONS = %s\n", (char *) glGetString(GL_EXTENSIONS));
858      if ( has_OML_sync_control || force_get_rate ) {
859	 show_refresh_rate( dpy );
860      }
861
862      if ( get_swap_interval != NULL ) {
863	 printf("Default swap interval = %d\n", (*get_swap_interval)() );
864      }
865   }
866
867   if ( do_swap_interval ) {
868      if ( set_swap_interval != NULL ) {
869	 if ( ((swap_interval == 0) && !has_MESA_swap_control)
870	      || (swap_interval < 0) ) {
871	    printf( "Swap interval must be non-negative or greater than zero "
872		    "if GLX_MESA_swap_control is not supported.\n" );
873	 }
874	 else {
875	    (*set_swap_interval)( swap_interval );
876	 }
877
878	 if ( printInfo && (get_swap_interval != NULL) ) {
879	    printf("Current swap interval = %d\n", (*get_swap_interval)() );
880	 }
881      }
882      else {
883	 printf("Unable to set swap-interval.  Neither GLX_SGI_swap_control "
884		"nor GLX_MESA_swap_control are supported.\n" );
885      }
886   }
887
888   init();
889
890   /* Set initial projection/viewing transformation.
891    * same as glxgears.c
892    */
893   reshape(width, height);
894
895   event_loop(dpy, win);
896
897   glXDestroyContext(dpy, ctx);
898   XDestroyWindow(dpy, win);
899   XCloseDisplay(dpy);
900
901   return 0;
902}
903