progs/xdemos/shape.c

   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 <X11/Xlib.h>
  21 #include <X11/Xutil.h>
  22 #include <X11/keysym.h>
  23 #include <X11/extensions/shape.h>
  24 #include <GL/glx.h>
  25
  26 #ifndef PI
  27 #define PI 3.1415926
  28 #endif
  29
  30
  31 static int Width=500, Height=500;
  32
  33 static float Xangle = 0.0, Yangle = 0.0;
  34 static int Redraw = 0;
  35 static int Sides = 5;
  36 static int MinSides = 3;
  37 static int MaxSides = 20;
  38
  39
  40 /*
  41  * Draw the OpenGL stuff and do a SwapBuffers.
  42  */
  43 static void display(Display *dpy, Window win)
  44 {
  45    float scale = 1.7;
  46
  47    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  48
  49    glPushMatrix();
  50
  51    glScalef(scale, scale, scale);
  52    glRotatef(Xangle, 1.0, 0.0, 0.0);
  53    glRotatef(Yangle, 0.0, 1.0, 0.0);
  54
  55    /*
  56     * wireframe box
  57     */
  58    glColor3f(1.0, 1.0, 1.0);
  59    glBegin(GL_LINE_LOOP);
  60    glVertex3f(-1.0, -1.0, -1.0);
  61    glVertex3f( 1.0, -1.0, -1.0);
  62    glVertex3f( 1.0,  1.0, -1.0);
  63    glVertex3f(-1.0,  1.0, -1.0);
  64    glEnd();
  65
  66    glBegin(GL_LINE_LOOP);
  67    glVertex3f(-1.0, -1.0, 1.0);
  68    glVertex3f( 1.0, -1.0, 1.0);
  69    glVertex3f( 1.0,  1.0, 1.0);
  70    glVertex3f(-1.0,  1.0, 1.0);
  71    glEnd();
  72
  73    glBegin(GL_LINES);
  74    glVertex3f(-1.0, -1.0, -1.0);   glVertex3f(-1.0, -1.0, 1.0);
  75    glVertex3f( 1.0, -1.0, -1.0);   glVertex3f( 1.0, -1.0, 1.0);
  76    glVertex3f( 1.0,  1.0, -1.0);   glVertex3f( 1.0,  1.0, 1.0);
  77    glVertex3f(-1.0,  1.0, -1.0);   glVertex3f(-1.0,  1.0, 1.0);
  78    glEnd();
  79
  80    /*
  81     * Solid box
  82     */
  83    glPushMatrix();
  84    glScalef(0.75, 0.75, 0.75);
  85
  86    glColor3f(1, 0, 0);
  87    glBegin(GL_POLYGON);
  88    glVertex3f(1, -1, -1);
  89    glVertex3f(1,  1, -1);
  90    glVertex3f(1,  1,  1);
  91    glVertex3f(1, -1,  1);
  92    glEnd();
  93
  94    glColor3f(0, 1, 1);
  95    glBegin(GL_POLYGON);
  96    glVertex3f(-1, -1, -1);
  97    glVertex3f(-1,  1, -1);
  98    glVertex3f(-1,  1,  1);
  99    glVertex3f(-1, -1,  1);
 100    glEnd();
 101
 102    glColor3f(0, 1, 0);
 103    glBegin(GL_POLYGON);
 104    glVertex3f(-1, 1, -1);
 105    glVertex3f( 1, 1, -1);
 106    glVertex3f( 1, 1,  1);
 107    glVertex3f(-1, 1,  1);
 108    glEnd();
 109
 110    glColor3f(1, 0, 1);
 111    glBegin(GL_POLYGON);
 112    glVertex3f(-1, -1, -1);
 113    glVertex3f( 1, -1, -1);
 114    glVertex3f( 1, -1,  1);
 115    glVertex3f(-1, -1,  1);
 116    glEnd();
 117
 118    glColor3f(0, 0, 1);
 119    glBegin(GL_POLYGON);
 120    glVertex3f(-1, -1, 1);
 121    glVertex3f( 1, -1, 1);
 122    glVertex3f( 1,  1, 1);
 123    glVertex3f(-1,  1, 1);
 124    glEnd();
 125
 126    glColor3f(1, 1, 0);
 127    glBegin(GL_POLYGON);
 128    glVertex3f(-1, -1, -1);
 129    glVertex3f( 1, -1, -1);
 130    glVertex3f( 1,  1, -1);
 131    glVertex3f(-1,  1, -1);
 132    glEnd();
 133    glPopMatrix();
 134
 135
 136    glPopMatrix();
 137
 138    glXSwapBuffers(dpy, win);
 139 }
 140
 141
 142 /*
 143  * Called when no events are pending.
 144  */
 145 static void idle(void)
 146 {
 147    Xangle += 2.0;
 148    Yangle += 3.3;
 149    Redraw = 1;
 150 }
 151
 152
 153 /*
 154  * This is called when we have to recompute the window shape bitmask.
 155  * We just generate an n-sided regular polygon here but any other shape
 156  * would be possible.
 157  */
 158 static void make_shape_mask(Display *dpy, Window win, int width, int height,
 159                             int sides)
 160 {
 161    Pixmap shapeMask;
 162    XGCValues xgcv;
 163    GC gc;
 164
 165    /* allocate 1-bit deep pixmap and a GC */
 166    shapeMask = XCreatePixmap(dpy, win, width, height, 1);
 167    gc = XCreateGC(dpy, shapeMask, 0, &xgcv);
 168
 169    /* clear shapeMask to zeros */
 170    XSetForeground(dpy, gc, 0);
 171    XFillRectangle(dpy, shapeMask, gc, 0, 0, width, height);
 172
 173    /* draw mask */
 174    XSetForeground(dpy, gc, 1);
 175    {
 176       int cx = width / 2;
 177       int cy = height / 2;
 178       float angle = 0.0;
 179       float step = 2.0 * PI / sides;
 180       float radius = width / 2;
 181       int i;
 182       XPoint points[100];
 183       for (i=0;i<sides;i++) {
 184          int x = cx + radius * sin(angle);
 185          int y = cy - radius * cos(angle);
 186          points[i].x = x;
 187          points[i].y = y;
 188          angle += step;
 189       }
 190       XFillPolygon(dpy, shapeMask, gc, points, sides, Convex, CoordModeOrigin);
 191    }
 192
 193    /* This is the only SHAPE extension call- simple! */
 194    XShapeCombineMask(dpy, win, ShapeBounding, 0, 0, shapeMask, ShapeSet);
 195
 196    XFreeGC(dpy, gc);
 197    XFreePixmap(dpy, shapeMask);
 198 }
 199
 200
 201 /*
 202  * Called when window is resized.  Do OpenGL viewport and projection stuff.
 203  */
 204 static void reshape(int width, int height)
 205 {
 206    glViewport(0, 0, width, height);
 207    glMatrixMode(GL_PROJECTION);
 208    glLoadIdentity();
 209    glFrustum(-1.0, 1.0, -1.0, 1.0, 3.0, 20.0);
 210    glMatrixMode(GL_MODELVIEW);
 211    glLoadIdentity();
 212    glTranslatef(0.0, 0.0, -10.0);
 213
 214    glEnable(GL_DEPTH_TEST);
 215 }
 216
 217
 218 /*
 219  * Process X events.
 220  */
 221 static void event_loop(Display *dpy, Window win)
 222 {
 223    while (1) {
 224       XEvent event;
 225       if (XPending(dpy)) {
 226          XNextEvent(dpy, &event);
 227          switch (event.type) {
 228             case Expose:
 229                display(dpy, event.xexpose.window);
 230                break;
 231             case ConfigureNotify:
 232                Width = event.xconfigure.width;
 233                Height = event.xconfigure.height,
 234                make_shape_mask(dpy, win, Width, Height, Sides);
 235                reshape(Width, Height);
 236                break;
 237             case KeyPress:
 238                {
 239                   char buf[100];
 240                   KeySym keySym;
 241                   XComposeStatus stat;
 242                   XLookupString(&event.xkey, buf, sizeof(buf), &keySym, &stat);
 243                   switch (keySym) {
 244                      case XK_Escape:
 245                         exit(0);
 246                         break;
 247                      case XK_Up:
 248                         Sides++;
 249                         if (Sides>MaxSides) Sides = MaxSides;
 250                         make_shape_mask(dpy, win, Width, Height, Sides);
 251                         break;
 252                      case XK_Down:
 253                         Sides--;
 254                         if (Sides<MinSides) Sides = MinSides;
 255                         make_shape_mask(dpy, win, Width, Height, Sides);
 256                         break;
 257                   }
 258                }
 259                break;
 260             default:
 261                ;;
 262          }
 263       }
 264       else {
 265          idle();
 266          if (Redraw) {
 267             display(dpy, win);
 268             Redraw = 0;
 269          }
 270       }
 271    }
 272 }
 273
 274
 275 /*
 276  * Allocate a "nice" colormap.  This could be better (HP-CR support, etc).
 277  */
 278 static Colormap alloc_colormap(Display *dpy, Window parent, Visual *vis)
 279 {
 280    Screen *scr = DefaultScreenOfDisplay(dpy);
 281    int scrnum = DefaultScreen(dpy);
 282
 283    if (MaxCmapsOfScreen(scr)==1 && vis==DefaultVisual(dpy, scrnum)) {
 284       /* The window and root are of the same visual type so */
 285       /* share the root colormap. */
 286       return DefaultColormap(dpy, scrnum);
 287    }
 288    else {
 289       return XCreateColormap(dpy, parent, vis, AllocNone);
 290    }
 291 }
 292
 293
 294 int main(int argc, char *argv[])
 295 {
 296    static int glAttribs[] = {
 297       GLX_DOUBLEBUFFER,
 298       GLX_RGBA,
 299       GLX_DEPTH_SIZE, 1,
 300       None
 301    };
 302    Display *dpy;
 303    XVisualInfo *visInfo;
 304    int scrn;
 305    Window root;
 306    Colormap cmap;
 307    Window win;
 308    XSetWindowAttributes winAttribs;
 309    unsigned long winAttribsMask;
 310    GLXContext glCtx;
 311    int ignore;
 312    const char *name = "OpenGL in a Shaped Window";
 313
 314    dpy = XOpenDisplay(NULL);
 315    if (!dpy) {
 316       fprintf(stderr, "Couldn't open default display\n");
 317       return 1;
 318    }
 319
 320    /* check that we can use the shape extension */
 321    if (!XQueryExtension(dpy, "SHAPE", &ignore, &ignore, &ignore )) {
 322       fprintf(stderr, "Display doesn't support shape extension\n");
 323       return 1;
 324    }
 325
 326    scrn = DefaultScreen(dpy);
 327
 328    root = RootWindow(dpy, scrn);
 329
 330    visInfo = glXChooseVisual(dpy, scrn, glAttribs);
 331    if (!visInfo) {
 332       fprintf(stderr, "Couldn't get RGB, DB, Z visual\n");
 333       return 1;
 334    }
 335
 336    glCtx = glXCreateContext(dpy, visInfo, 0, True);
 337    if (!glCtx) {
 338       fprintf(stderr, "Couldn't create GL context\n");
 339       return 1;
 340    }
 341
 342    cmap = alloc_colormap(dpy, root, visInfo->visual);
 343    if (!cmap) {
 344       fprintf(stderr, "Couln't create colormap\n");
 345       return 1;
 346    }
 347
 348    winAttribs.border_pixel = 0;
 349    winAttribs.colormap = cmap;
 350    winAttribs.event_mask = StructureNotifyMask | ExposureMask | KeyPressMask;
 351    winAttribsMask = CWBorderPixel | CWColormap | CWEventMask;
 352    win = XCreateWindow(dpy, root, 0, 0, Width, Height, 0,
 353                        visInfo->depth, InputOutput,
 354                        visInfo->visual,
 355                        winAttribsMask, &winAttribs);
 356
 357    {
 358       XSizeHints sizehints;
 359       /*
 360       sizehints.x = xpos;
 361       sizehints.y = ypos;
 362       sizehints.width  = width;
 363       sizehints.height = height;
 364       */
 365       sizehints.flags = 0;
 366       XSetNormalHints(dpy, win, &sizehints);
 367       XSetStandardProperties(dpy, win, name, name,
 368                               None, (char **)NULL, 0, &sizehints);
 369    }
 370
 371
 372    XMapWindow(dpy, win);
 373
 374    glXMakeCurrent(dpy, win, glCtx);
 375
 376    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
 377    printf("Press ESC to exit.\n");
 378    printf("Press up/down to change window shape.\n");
 379
 380    event_loop(dpy, win);
 381
 382    return 0;
 383 }