1
2/*
3 * Example of using the X "shape" extension with OpenGL:  render a spinning
4 * cube inside of a non-rectangular window.
5 *
6 * Press ESC to exit.  Press up/down to change window shape.
7 *
8 * To compile add "shape" to the PROGS list in Makefile.
9 *
10 * Brian Paul
11 * June 16, 1997
12 *
13 * This program is in the public domain.
14 */
15
16
17#include <math.h>
18#include <stdio.h>
19#include <stdlib.h>
20#include <sys/time.h>
21#include <time.h>
22#include <unistd.h>
23#include <X11/Xlib.h>
24#include <X11/Xutil.h>
25#include <X11/keysym.h>
26#include <X11/extensions/shape.h>
27#include <GL/glx.h>
28
29#ifndef PI
30#define PI 3.1415926
31#endif
32
33
34static int Width=500, Height=500;
35
36static float Xangle = 0.0, Yangle = 0.0;
37static int Sides = 5;
38static int MinSides = 3;
39static int MaxSides = 20;
40
41
42/* return current time (in seconds) */
43static double
44current_time(void)
45{
46   struct timeval tv;
47#ifdef __VMS
48   (void) gettimeofday(&tv, NULL );
49#else
50   struct timezone tz;
51   (void) gettimeofday(&tv, &tz);
52#endif
53   return (double) tv.tv_sec + tv.tv_usec / 1000000.0;
54}
55
56
57/*
58 * Draw the OpenGL stuff and do a SwapBuffers.
59 */
60static void display(Display *dpy, Window win)
61{
62   float scale = 1.7;
63
64   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
65
66   glPushMatrix();
67
68   glScalef(scale, scale, scale);
69   glRotatef(Xangle, 1.0, 0.0, 0.0);
70   glRotatef(Yangle, 0.0, 1.0, 0.0);
71
72   /*
73    * wireframe box
74    */
75   glColor3f(1.0, 1.0, 1.0);
76   glBegin(GL_LINE_LOOP);
77   glVertex3f(-1.0, -1.0, -1.0);
78   glVertex3f( 1.0, -1.0, -1.0);
79   glVertex3f( 1.0,  1.0, -1.0);
80   glVertex3f(-1.0,  1.0, -1.0);
81   glEnd();
82
83   glBegin(GL_LINE_LOOP);
84   glVertex3f(-1.0, -1.0, 1.0);
85   glVertex3f( 1.0, -1.0, 1.0);
86   glVertex3f( 1.0,  1.0, 1.0);
87   glVertex3f(-1.0,  1.0, 1.0);
88   glEnd();
89
90   glBegin(GL_LINES);
91   glVertex3f(-1.0, -1.0, -1.0);   glVertex3f(-1.0, -1.0, 1.0);
92   glVertex3f( 1.0, -1.0, -1.0);   glVertex3f( 1.0, -1.0, 1.0);
93   glVertex3f( 1.0,  1.0, -1.0);   glVertex3f( 1.0,  1.0, 1.0);
94   glVertex3f(-1.0,  1.0, -1.0);   glVertex3f(-1.0,  1.0, 1.0);
95   glEnd();
96
97   /*
98    * Solid box
99    */
100   glPushMatrix();
101   glScalef(0.75, 0.75, 0.75);
102
103   glColor3f(1, 0, 0);
104   glBegin(GL_POLYGON);
105   glVertex3f(1, -1, -1);
106   glVertex3f(1,  1, -1);
107   glVertex3f(1,  1,  1);
108   glVertex3f(1, -1,  1);
109   glEnd();
110
111   glColor3f(0, 1, 1);
112   glBegin(GL_POLYGON);
113   glVertex3f(-1, -1, -1);
114   glVertex3f(-1,  1, -1);
115   glVertex3f(-1,  1,  1);
116   glVertex3f(-1, -1,  1);
117   glEnd();
118
119   glColor3f(0, 1, 0);
120   glBegin(GL_POLYGON);
121   glVertex3f(-1, 1, -1);
122   glVertex3f( 1, 1, -1);
123   glVertex3f( 1, 1,  1);
124   glVertex3f(-1, 1,  1);
125   glEnd();
126
127   glColor3f(1, 0, 1);
128   glBegin(GL_POLYGON);
129   glVertex3f(-1, -1, -1);
130   glVertex3f( 1, -1, -1);
131   glVertex3f( 1, -1,  1);
132   glVertex3f(-1, -1,  1);
133   glEnd();
134
135   glColor3f(0, 0, 1);
136   glBegin(GL_POLYGON);
137   glVertex3f(-1, -1, 1);
138   glVertex3f( 1, -1, 1);
139   glVertex3f( 1,  1, 1);
140   glVertex3f(-1,  1, 1);
141   glEnd();
142
143   glColor3f(1, 1, 0);
144   glBegin(GL_POLYGON);
145   glVertex3f(-1, -1, -1);
146   glVertex3f( 1, -1, -1);
147   glVertex3f( 1,  1, -1);
148   glVertex3f(-1,  1, -1);
149   glEnd();
150   glPopMatrix();
151
152
153   glPopMatrix();
154
155   glXSwapBuffers(dpy, win);
156}
157
158
159/*
160 * This is called when we have to recompute the window shape bitmask.
161 * We just generate an n-sided regular polygon here but any other shape
162 * would be possible.
163 */
164static void make_shape_mask(Display *dpy, Window win, int width, int height,
165                            int sides)
166{
167   Pixmap shapeMask;
168   XGCValues xgcv;
169   GC gc;
170
171   /* allocate 1-bit deep pixmap and a GC */
172   shapeMask = XCreatePixmap(dpy, win, width, height, 1);
173   gc = XCreateGC(dpy, shapeMask, 0, &xgcv);
174
175   /* clear shapeMask to zeros */
176   XSetForeground(dpy, gc, 0);
177   XFillRectangle(dpy, shapeMask, gc, 0, 0, width, height);
178
179   /* draw mask */
180   XSetForeground(dpy, gc, 1);
181   {
182      int cx = width / 2;
183      int cy = height / 2;
184      float angle = 0.0;
185      float step = 2.0 * PI / sides;
186      float radius = width / 2;
187      int i;
188      XPoint points[100];
189      for (i=0;i<sides;i++) {
190         int x = cx + radius * sin(angle);
191         int y = cy - radius * cos(angle);
192         points[i].x = x;
193         points[i].y = y;
194         angle += step;
195      }
196      XFillPolygon(dpy, shapeMask, gc, points, sides, Convex, CoordModeOrigin);
197   }
198
199   /* This is the only SHAPE extension call- simple! */
200   XShapeCombineMask(dpy, win, ShapeBounding, 0, 0, shapeMask, ShapeSet);
201
202   XFreeGC(dpy, gc);
203   XFreePixmap(dpy, shapeMask);
204}
205
206
207/*
208 * Called when window is resized.  Do OpenGL viewport and projection stuff.
209 */
210static void reshape(int width, int height)
211{
212   glViewport(0, 0, width, height);
213   glMatrixMode(GL_PROJECTION);
214   glLoadIdentity();
215   glFrustum(-1.0, 1.0, -1.0, 1.0, 3.0, 20.0);
216   glMatrixMode(GL_MODELVIEW);
217   glLoadIdentity();
218   glTranslatef(0.0, 0.0, -10.0);
219
220   glEnable(GL_DEPTH_TEST);
221}
222
223
224/*
225 * Process X events.
226 */
227static void event_loop(Display *dpy, Window win)
228{
229   while (1) {
230      XEvent event;
231      if (XPending(dpy)) {
232         XNextEvent(dpy, &event);
233         switch (event.type) {
234            case Expose:
235               display(dpy, event.xexpose.window);
236               break;
237            case ConfigureNotify:
238               Width = event.xconfigure.width;
239               Height = event.xconfigure.height,
240               make_shape_mask(dpy, win, Width, Height, Sides);
241               reshape(Width, Height);
242               break;
243            case KeyPress:
244               {
245                  char buf[100];
246                  KeySym keySym;
247                  XComposeStatus stat;
248                  XLookupString(&event.xkey, buf, sizeof(buf), &keySym, &stat);
249                  switch (keySym) {
250                     case XK_Escape:
251                        exit(0);
252                        break;
253                     case XK_Up:
254                        Sides++;
255                        if (Sides>MaxSides) Sides = MaxSides;
256                        make_shape_mask(dpy, win, Width, Height, Sides);
257                        break;
258                     case XK_Down:
259                        Sides--;
260                        if (Sides<MinSides) Sides = MinSides;
261                        make_shape_mask(dpy, win, Width, Height, Sides);
262                        break;
263                  }
264               }
265               break;
266            default:
267               ;;
268         }
269      }
270      else {
271         static double t0 = -1.0;
272         double dt, t = current_time();
273         if (t0 < 0.0)
274            t0 = t;
275         dt = t - t0;
276         Xangle += 90.0 * dt;  /* 90 degrees per second */
277         Yangle += 70.0 * dt;
278         t0 = t;
279         display(dpy, win);
280      }
281   }
282}
283
284
285/*
286 * Allocate a "nice" colormap.  This could be better (HP-CR support, etc).
287 */
288static Colormap alloc_colormap(Display *dpy, Window parent, Visual *vis)
289{
290   Screen *scr = DefaultScreenOfDisplay(dpy);
291   int scrnum = DefaultScreen(dpy);
292
293   if (MaxCmapsOfScreen(scr)==1 && vis==DefaultVisual(dpy, scrnum)) {
294      /* The window and root are of the same visual type so */
295      /* share the root colormap. */
296      return DefaultColormap(dpy, scrnum);
297   }
298   else {
299      return XCreateColormap(dpy, parent, vis, AllocNone);
300   }
301}
302
303
304int main(int argc, char *argv[])
305{
306   static int glAttribs[] = {
307      GLX_DOUBLEBUFFER,
308      GLX_RGBA,
309      GLX_DEPTH_SIZE, 1,
310      None
311   };
312   Display *dpy;
313   XVisualInfo *visInfo;
314   int scrn;
315   Window root;
316   Colormap cmap;
317   Window win;
318   XSetWindowAttributes winAttribs;
319   unsigned long winAttribsMask;
320   GLXContext glCtx;
321   int ignore;
322   const char *name = "OpenGL in a Shaped Window";
323
324   dpy = XOpenDisplay(NULL);
325   if (!dpy) {
326      fprintf(stderr, "Couldn't open default display\n");
327      return 1;
328   }
329
330   /* check that we can use the shape extension */
331   if (!XQueryExtension(dpy, "SHAPE", &ignore, &ignore, &ignore )) {
332      fprintf(stderr, "Display doesn't support shape extension\n");
333      return 1;
334   }
335
336   scrn = DefaultScreen(dpy);
337
338   root = RootWindow(dpy, scrn);
339
340   visInfo = glXChooseVisual(dpy, scrn, glAttribs);
341   if (!visInfo) {
342      fprintf(stderr, "Couldn't get RGB, DB, Z visual\n");
343      return 1;
344   }
345
346   glCtx = glXCreateContext(dpy, visInfo, 0, True);
347   if (!glCtx) {
348      fprintf(stderr, "Couldn't create GL context\n");
349      return 1;
350   }
351
352   cmap = alloc_colormap(dpy, root, visInfo->visual);
353   if (!cmap) {
354      fprintf(stderr, "Couln't create colormap\n");
355      return 1;
356   }
357
358   winAttribs.border_pixel = 0;
359   winAttribs.colormap = cmap;
360   winAttribs.event_mask = StructureNotifyMask | ExposureMask | KeyPressMask;
361   winAttribsMask = CWBorderPixel | CWColormap | CWEventMask;
362   win = XCreateWindow(dpy, root, 0, 0, Width, Height, 0,
363                       visInfo->depth, InputOutput,
364                       visInfo->visual,
365                       winAttribsMask, &winAttribs);
366
367   {
368      XSizeHints sizehints;
369      /*
370      sizehints.x = xpos;
371      sizehints.y = ypos;
372      sizehints.width  = width;
373      sizehints.height = height;
374      */
375      sizehints.flags = 0;
376      XSetNormalHints(dpy, win, &sizehints);
377      XSetStandardProperties(dpy, win, name, name,
378                              None, (char **)NULL, 0, &sizehints);
379   }
380
381
382   XMapWindow(dpy, win);
383
384   glXMakeCurrent(dpy, win, glCtx);
385
386   printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
387   printf("Press ESC to exit.\n");
388   printf("Press up/down to change window shape.\n");
389
390   event_loop(dpy, win);
391
392   return 0;
393}
394