source/main.c

   1 #define GL_GLEXT_PROTOTYPES
   2 #include <stdio.h>
   3 #include <stdlib.h>
   4 #include <string.h>
   5 #include <signal.h>
   6 #include <X11/Xlib.h>
   7 #include <X11/extensions/Xcomposite.h>
   8 #include <X11/extensions/Xdamage.h>
   9 #include <X11/extensions/shape.h>
  10 #include <GL/gl.h>
  11 #include <GL/glx.h>
  12
  13 typedef struct CompositedWindow
  14 {
  15         Window window;
  16         int x;
  17         int y;
  18         unsigned width;
  19         unsigned height;
  20         unsigned border;
  21         int map_state;
  22         Damage damage;
  23         Pixmap pixmap;
  24         GLXPixmap glx_pixmap;
  25         unsigned texture;
  26 } CompositedWindow;
  27
  28 typedef struct CompositedScreen
  29 {
  30         int number;
  31         Window root;
  32         unsigned width;
  33         unsigned height;
  34         Window overlay;
  35         Window render_window;
  36         GLXFBConfig fbconfig;
  37         GLXWindow glx_window;
  38         GLXContext glx_context;
  39         unsigned shaders[2];
  40         unsigned program;
  41         unsigned geometry_loc;
  42         unsigned vertex_buffer;
  43         unsigned vertex_array;
  44         CompositedWindow *windows;
  45         unsigned nwindows;
  46         unsigned windows_capacity;
  47         int dirty;
  48 } CompositedScreen;
  49
  50 typedef struct Compositor
  51 {
  52         Display *display;
  53         CompositedScreen *screens;
  54         unsigned nscreens;
  55         int damage_event;
  56         PFNGLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribsARB;
  57         PFNGLXBINDTEXIMAGEEXTPROC glXBindTexImageEXT;
  58         PFNGLXRELEASETEXIMAGEEXTPROC glXReleaseTexImageEXT;
  59         int dirty;
  60 } Compositor;
  61
  62 static const char *vshader =
  63         "#version 150\n"
  64         "uniform vec4 geometry;\n"
  65         "in vec2 vertex;\n"
  66         "out vec2 texcoord;\n"
  67         "void main()\n"
  68         "{\n"
  69         "  gl_Position = vec4((geometry.xy+vertex*geometry.zw)*2.0-1.0, 0.0, 1.0);\n"
  70         "  texcoord = vec2(vertex.x, 1.0-vertex.y);\n"
  71         "}\n";
  72
  73 static const char *fshader =
  74         "#version 150\n"
  75         "uniform sampler2D window;\n"
  76         "in vec2 texcoord;\n"
  77         "out vec4 frag_color;\n"
  78         "void main()\n"
  79         "{\n"
  80         "       frag_color = texture(window, texcoord);\n"
  81         "}\n";
  82
  83 static const float vertices[] =
  84 {
  85         0.0f, 1.0f,
  86         0.0f, 0.0f,
  87         1.0f, 1.0f,
  88         1.0f, 0.0f
  89 };
  90
  91 int terminate_requested = 0;
  92
  93 int x_error_handler(Display *display, XErrorEvent *event)
  94 {
  95         printf("Ignoring X error %d on resource %lx\n", event->error_code, event->resourceid);
  96         (void)display;
  97         return 0;
  98 }
  99
 100 int with_error(const char *message)
 101 {
 102         fprintf(stderr, "%s\n", message);
 103         return 0;
 104 }
 105
 106 int initialize_gl(Compositor *compositor, CompositedScreen *screen)
 107 {
 108         int attribs[9];
 109         unsigned i;
 110         GLXFBConfig *configs;
 111         int nconfigs;
 112         XVisualInfo *vi;
 113         XSetWindowAttributes win_attr;
 114
 115         i = 0;
 116         attribs[i++] = GLX_DRAWABLE_TYPE;
 117         attribs[i++] = GLX_WINDOW_BIT;
 118         attribs[i++] = GLX_RENDER_TYPE;
 119         attribs[i++] = GLX_RGBA_BIT;
 120         attribs[i++] = GLX_DOUBLEBUFFER;
 121         attribs[i++] = True;
 122         attribs[i++] = GLX_BIND_TO_TEXTURE_RGBA_EXT;
 123         attribs[i++] = True;
 124         attribs[i] = None;
 125
 126         configs = glXChooseFBConfig(compositor->display, screen->number, attribs, &nconfigs);
 127         if(!configs || !nconfigs)
 128                 return with_error("Could not find a suitable FBConfig");
 129         screen->fbconfig = configs[0];
 130         XFree(configs);
 131
 132         vi = glXGetVisualFromFBConfig(compositor->display, screen->fbconfig);
 133         win_attr.colormap = XCreateColormap(compositor->display, screen->root, vi->visual, AllocNone);
 134         screen->render_window = XCreateWindow(compositor->display, screen->overlay, 0, 0, screen->width, screen->height, 0, vi->depth, InputOutput, vi->visual, CWColormap, &win_attr);
 135         XMapWindow(compositor->display, screen->render_window);
 136
 137         screen->glx_window = glXCreateWindow(compositor->display, screen->fbconfig, screen->render_window, NULL);
 138
 139         i = 0;
 140         attribs[i++] = GLX_CONTEXT_FLAGS_ARB;
 141         attribs[i++] = GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB;
 142         attribs[i++] = GLX_CONTEXT_MAJOR_VERSION_ARB;
 143         attribs[i++] = 3;
 144         attribs[i++] = GLX_CONTEXT_MINOR_VERSION_ARB;
 145         attribs[i++] = 0;
 146         attribs[i] = None;
 147
 148         screen->glx_context = compositor->glXCreateContextAttribsARB(compositor->display, screen->fbconfig, NULL, True, attribs);
 149
 150         XFree(vi);
 151
 152         return 1;
 153 }
 154
 155 void use_gl(Compositor *compositor, CompositedScreen *screen)
 156 {
 157         glXMakeContextCurrent(compositor->display, screen->glx_window, screen->glx_window, screen->glx_context);
 158 }
 159
 160 unsigned compile_shader(GLenum type, const char *source)
 161 {
 162         unsigned shader;
 163         int status;
 164         char info_log[1024];
 165         GLsizei length;
 166
 167         shader = glCreateShader(type);
 168         glShaderSource(shader, 1, &source, NULL);
 169         glCompileShader(shader);
 170         glGetShaderiv(shader, GL_COMPILE_STATUS, &status);
 171         glGetShaderInfoLog(shader, sizeof(info_log), &length, info_log);
 172         if(!status)
 173         {
 174                 fprintf(stderr, "Shader compilation failed:\n%s\n", info_log);
 175                 glDeleteShader(shader);
 176                 return 0;
 177         }
 178         else if(length)
 179                 printf("Shader info log:\n%s\n", info_log);
 180
 181         return shader;
 182 }
 183
 184 int create_gl_resources(Compositor *compositor, CompositedScreen *screen)
 185 {
 186         int status;
 187         char info_log[1024];
 188         GLsizei length;
 189
 190         use_gl(compositor, screen);
 191
 192         screen->shaders[0] = compile_shader(GL_VERTEX_SHADER, vshader);
 193         screen->shaders[1] = compile_shader(GL_FRAGMENT_SHADER, fshader);
 194         if(!screen->shaders[0] || !screen->shaders[1])
 195                 return 0;
 196
 197         screen->program = glCreateProgram();
 198         glAttachShader(screen->program, screen->shaders[0]);
 199         glAttachShader(screen->program, screen->shaders[1]);
 200         glBindAttribLocation(screen->program, 0, "vertex");
 201         glLinkProgram(screen->program);
 202
 203         screen->geometry_loc = glGetUniformLocation(screen->program, "geometry");
 204
 205         glGetProgramiv(screen->program, GL_LINK_STATUS, &status);
 206         glGetProgramInfoLog(screen->program, sizeof(info_log), &length, info_log);
 207         if(!status)
 208         {
 209                 fprintf(stderr, "Program link failed:\n%s\n", info_log);
 210                 glDeleteProgram(screen->program);
 211                 return 0;
 212         }
 213         else if(length)
 214                 printf("Program info log:\n%s\n", info_log);
 215
 216         glGenBuffers(1, &screen->vertex_buffer);
 217         glBindBuffer(GL_ARRAY_BUFFER, screen->vertex_buffer);
 218         glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
 219
 220         glGenVertexArrays(1, &screen->vertex_array);
 221         glBindVertexArray(screen->vertex_array);
 222         glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, NULL);
 223         glEnableVertexAttribArray(0);
 224
 225         glBindBuffer(GL_ARRAY_BUFFER, 0);
 226
 227         return 1;
 228 }
 229
 230 CompositedWindow *find_window(CompositedScreen *screen, Window w)
 231 {
 232         unsigned i;
 233
 234         for(i=0; i<screen->nwindows; ++i)
 235                 if(screen->windows[i].window==w)
 236                         return &screen->windows[i];
 237
 238         return NULL;
 239 }
 240
 241 void create_window_pixmap(Compositor *compositor, CompositedScreen *screen, CompositedWindow *window)
 242 {
 243         int attribs[5];
 244         unsigned i;
 245
 246         if(window->pixmap)
 247         {
 248                 glXDestroyPixmap(compositor->display, window->glx_pixmap);
 249                 XFreePixmap(compositor->display, window->pixmap);
 250         }
 251
 252         i = 0;
 253         attribs[i++] = GLX_TEXTURE_TARGET_EXT;
 254         attribs[i++] = GLX_TEXTURE_2D_EXT;
 255         attribs[i++] = GLX_TEXTURE_FORMAT_EXT;
 256         attribs[i++] = GLX_TEXTURE_FORMAT_RGBA_EXT;
 257         attribs[i++] = None;
 258
 259         window->pixmap = XCompositeNameWindowPixmap(compositor->display, window->window);
 260         window->glx_pixmap = glXCreatePixmap(compositor->display, screen->fbconfig, window->pixmap, attribs);
 261 }
 262
 263 CompositedWindow *add_window(Compositor *compositor, CompositedScreen *screen, Window w)
 264 {
 265         CompositedWindow *window;
 266         XWindowAttributes win_attr;
 267
 268         if(w==screen->root || w==screen->overlay)
 269                 return NULL;
 270
 271         if(!XGetWindowAttributes(compositor->display, w, &win_attr))
 272         {
 273                 printf("XGetWindowAttributes failed; probably the window was already destroyed\n");
 274                 return NULL;
 275         }
 276         if(win_attr.class==InputOnly)
 277                 return NULL;
 278
 279         if(find_window(screen, w))
 280                 return NULL;
 281
 282         if(screen->nwindows==screen->windows_capacity)
 283         {
 284                 screen->windows = (CompositedWindow *)realloc(screen->windows, (screen->windows_capacity+1)*sizeof(CompositedWindow));
 285                 ++screen->windows_capacity;
 286         }
 287
 288         window = &screen->windows[screen->nwindows++];
 289
 290         window->window = w;
 291         window->x = win_attr.x;
 292         window->y = win_attr.y;
 293         window->width = win_attr.width;
 294         window->height = win_attr.height;
 295         window->border = win_attr.border_width;
 296         window->map_state = win_attr.map_state;
 297
 298         window->damage = XDamageCreate(compositor->display, window->window, XDamageReportNonEmpty);
 299         window->pixmap = None;
 300         window->glx_pixmap = None;
 301
 302         XCompositeRedirectWindow(compositor->display, window->window, CompositeRedirectManual);
 303         if(window->map_state==IsViewable)
 304                 create_window_pixmap(compositor, screen, window);
 305
 306         glGenTextures(1, &window->texture);
 307         glBindTexture(GL_TEXTURE_2D, window->texture);
 308         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
 309         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
 310         glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
 311
 312         return window;
 313 }
 314
 315 void remove_window(Compositor *compositor, CompositedScreen *screen, CompositedWindow *window, int destroyed)
 316 {
 317         unsigned i;
 318
 319         glDeleteTextures(1, &window->texture);
 320         if(!destroyed)
 321         {
 322                 XDamageDestroy(compositor->display, window->damage);
 323                 if(window->pixmap)
 324                 {
 325                         glXDestroyPixmap(compositor->display, window->glx_pixmap);
 326                         XFreePixmap(compositor->display, window->pixmap);
 327                 }
 328                 XCompositeUnredirectWindow(compositor->display, window->window, CompositeRedirectManual);
 329         }
 330
 331         --screen->nwindows;
 332         for(i=window-screen->windows; i<screen->nwindows; ++i)
 333                 screen->windows[i] = screen->windows[i+1];
 334 }
 335
 336 CompositedScreen *find_screen_by_root(Compositor *compositor, Window root)
 337 {
 338         unsigned i;
 339
 340         for(i=0; i<compositor->nscreens; ++i)
 341                 if(compositor->screens[i].root==root)
 342                         return &compositor->screens[i];
 343
 344         return NULL;
 345 }
 346
 347 CompositedScreen *find_screen_by_window(Compositor *compositor, Window w)
 348 {
 349         unsigned i, j;
 350
 351         for(i=0; i<compositor->nscreens; ++i)
 352                 for(j=0; j<compositor->screens[i].nwindows; ++j)
 353                         if(compositor->screens[i].windows[j].window==w)
 354                                 return &compositor->screens[i];
 355
 356         return NULL;
 357 }
 358
 359 int initialize_screen(Compositor *compositor, unsigned number)
 360 {
 361         CompositedScreen *screen;
 362         const char *extensions;
 363         Window dummy_root;
 364         int x, y;
 365         unsigned border;
 366         unsigned depth;
 367         Window dummy_parent;
 368         Window *children;
 369         unsigned nchildren;
 370         unsigned i;
 371
 372         screen = &compositor->screens[number];
 373         screen->number = number;
 374
 375         extensions = glXQueryExtensionsString(compositor->display, screen->number);
 376         if(!strstr(extensions, "GLX_ARB_create_context"))
 377                 return with_error("GLX_ARB_create_context is required");
 378         if(!strstr(extensions, "GLX_EXT_texture_from_pixmap"))
 379                 return with_error("GLX_EXT_texture_from_pixmap is required");
 380
 381         screen->root = RootWindow(compositor->display, screen->number);
 382         XSelectInput(compositor->display, screen->root, SubstructureNotifyMask);
 383         screen->overlay = XCompositeGetOverlayWindow(compositor->display, screen->root);
 384         XGetGeometry(compositor->display, screen->overlay, &dummy_root, &x, &y, &screen->width, &screen->height, &border, &depth);
 385         XShapeCombineRectangles(compositor->display, screen->overlay, ShapeInput, 0, 0, NULL, 0, ShapeSet, Unsorted);
 386
 387         if(!initialize_gl(compositor, screen))
 388                 return 0;
 389
 390         if(!create_gl_resources(compositor, screen))
 391                 return 0;
 392
 393         XQueryTree(compositor->display, screen->root, &dummy_root, &dummy_parent, &children, &nchildren);
 394
 395         screen->windows = (CompositedWindow *)malloc(nchildren*sizeof(CompositedWindow));
 396         screen->nwindows = 0;
 397         screen->windows_capacity = nchildren;
 398
 399         for(i=0; i<nchildren; ++i)
 400                 add_window(compositor, screen, children[i]);
 401
 402         XFree(children);
 403
 404         screen->dirty = 1;
 405
 406         return 1;
 407 }
 408
 409 int initialize_compositor(Compositor *compositor)
 410 {
 411         int event_base;
 412         int error_base;
 413         int major_ver;
 414         int minor_ver;
 415         unsigned i;
 416
 417         compositor->display = XOpenDisplay(NULL);
 418         if(!compositor->display)
 419                 return with_error("Could not open X display");
 420
 421         XSetErrorHandler(&x_error_handler);
 422
 423         if(!XCompositeQueryExtension(compositor->display, &event_base, &error_base))
 424                 return with_error("XComposite is required but was not found");
 425         else if(!XCompositeQueryVersion(compositor->display, &major_ver, &minor_ver))
 426                 return with_error("Cannot determine XComposite version");
 427         else if(major_ver==0 && minor_ver<3)
 428                 return with_error("XComposite 0.3 or later is required");
 429
 430         if(!glXQueryExtension(compositor->display, &event_base, &error_base))
 431                 return with_error("GLX is required but was not found");
 432         else if(!glXQueryVersion(compositor->display, &major_ver, &minor_ver))
 433                 return with_error("Cannot determine GLX version");
 434         else if(major_ver<1 || (major_ver==1 && minor_ver<4))
 435                 return with_error("GLX 1.4 or later is required");
 436
 437         if(!XDamageQueryExtension(compositor->display, &compositor->damage_event, &error_base))
 438                 return with_error("XDamage is required but was not found");
 439         else if(!XDamageQueryVersion(compositor->display, &major_ver, &minor_ver))
 440                 return with_error("Cannot determine XDamage version");
 441         else if(major_ver<1)
 442                 return with_error("XDamage 1.0 or later is required");
 443
 444         if(!XShapeQueryExtension(compositor->display, &event_base, &error_base))
 445                 return with_error("XShape is required but was not found");
 446         else if(!XShapeQueryVersion(compositor->display, &major_ver, &minor_ver))
 447                 return with_error("Cannot determine XShape version");
 448         else if(major_ver<1 || (major_ver==1 && minor_ver<1))
 449                 return with_error("XShape 1.1 or later is required");
 450
 451         compositor->glXCreateContextAttribsARB = (PFNGLXCREATECONTEXTATTRIBSARBPROC)glXGetProcAddress((unsigned char *)"glXCreateContextAttribsARB");
 452         compositor->glXBindTexImageEXT = (PFNGLXBINDTEXIMAGEEXTPROC)glXGetProcAddress((unsigned char *)"glXBindTexImageEXT");
 453         compositor->glXReleaseTexImageEXT = (PFNGLXRELEASETEXIMAGEEXTPROC)glXGetProcAddress((unsigned char *)"glXReleaseTexImageEXT");
 454
 455         compositor->nscreens = ScreenCount(compositor->display);
 456         compositor->screens = (CompositedScreen *)malloc(compositor->nscreens*sizeof(CompositedScreen));
 457         for(i=0; i<compositor->nscreens; ++i)
 458                 if(!initialize_screen(compositor, i))
 459                         return 0;
 460
 461         compositor->dirty = 1;
 462
 463         return 1;
 464 }
 465
 466 void shutdown_screen(Compositor *compositor, CompositedScreen *screen)
 467 {
 468         unsigned i;
 469
 470         use_gl(compositor, screen);
 471
 472         for(i=0; i<screen->nwindows; ++i)
 473         {
 474                 glDeleteTextures(1, &screen->windows[i].texture);
 475                 if(screen->windows[i].pixmap)
 476                 {
 477                         glXDestroyPixmap(compositor->display, screen->windows[i].glx_pixmap);
 478                         XFreePixmap(compositor->display, screen->windows[i].pixmap);
 479                         XDamageDestroy(compositor->display, screen->windows[i].damage);
 480                 }
 481         }
 482
 483         glXMakeContextCurrent(compositor->display, 0, 0, NULL);
 484         glXDestroyContext(compositor->display, screen->glx_context);
 485         glXDestroyWindow(compositor->display, screen->glx_window);
 486         XDestroyWindow(compositor->display, screen->render_window);
 487
 488         XCompositeReleaseOverlayWindow(compositor->display, screen->overlay);
 489
 490         free(screen->windows);
 491 }
 492
 493 void shutdown_compositor(Compositor *compositor)
 494 {
 495         unsigned i;
 496
 497         for(i=0; i<compositor->nscreens; ++i)
 498                 shutdown_screen(compositor, &compositor->screens[i]);
 499         free(compositor->screens);
 500
 501         XCloseDisplay(compositor->display);
 502 }
 503
 504 void mark_dirty(Compositor *compositor, CompositedScreen *screen)
 505 {
 506         compositor->dirty = 1;
 507         screen->dirty = 1;
 508 }
 509
 510 void process_create_window_event(Compositor *compositor, XCreateWindowEvent *event)
 511 {
 512         CompositedScreen *screen = find_screen_by_root(compositor, event->parent);
 513         if(!screen)
 514                 return;
 515
 516         add_window(compositor, screen, event->window);
 517 }
 518
 519 void process_destroy_window_event(Compositor *compositor, XDestroyWindowEvent *event)
 520 {
 521         CompositedScreen *screen = find_screen_by_root(compositor, event->event);
 522         if(!screen)
 523                 return;
 524
 525         CompositedWindow *window = find_window(screen, event->window);
 526         if(window)
 527                 remove_window(compositor, screen, window, 1);
 528 }
 529
 530 void process_map_event(Compositor *compositor, XMapEvent *event)
 531 {
 532         CompositedScreen *screen = find_screen_by_root(compositor, event->event);
 533         if(!screen)
 534                 return;
 535
 536         CompositedWindow *window = find_window(screen, event->window);
 537         if(!window)
 538                 return;
 539
 540         window->map_state = IsViewable;
 541         create_window_pixmap(compositor, screen, window);
 542
 543         mark_dirty(compositor, screen);
 544 }
 545
 546 void process_unmap_event(Compositor *compositor, XUnmapEvent *event)
 547 {
 548         CompositedScreen *screen = find_screen_by_root(compositor, event->event);
 549         if(!screen)
 550                 return;
 551
 552         CompositedWindow *window = find_window(screen, event->window);
 553         if(window)
 554                 window->map_state = IsUnviewable;
 555
 556         mark_dirty(compositor, screen);
 557 }
 558
 559 void process_reparent_event(Compositor *compositor, XReparentEvent *event)
 560 {
 561         CompositedScreen *screen = find_screen_by_root(compositor, event->event);
 562         if(!screen)
 563                 return;
 564
 565         CompositedWindow *window;
 566         if(event->parent==screen->root)
 567                 window = add_window(compositor, screen, event->window);
 568         else
 569         {
 570                 window = find_window(screen, event->window);
 571                 if(!window)
 572                         return;
 573
 574                 remove_window(compositor, screen, window, 0);
 575         }
 576
 577         if(window && window->map_state==IsViewable)
 578                 mark_dirty(compositor, screen);
 579 }
 580
 581 void process_damage_event(Compositor *compositor, XDamageNotifyEvent *event)
 582 {
 583         CompositedScreen *screen = find_screen_by_window(compositor, event->drawable);
 584         if(!screen)
 585                 return;
 586
 587         CompositedWindow *window = find_window(screen, event->drawable);
 588         if(window->map_state==IsViewable)
 589                 mark_dirty(compositor, screen);
 590 }
 591
 592 int process_event(Compositor *compositor)
 593 {
 594         XEvent event;
 595         if(compositor->dirty)
 596         {
 597                 if(!XCheckMaskEvent(compositor->display, -1, &event))
 598                         return 0;
 599         }
 600         else
 601                 XNextEvent(compositor->display, &event);
 602
 603         switch(event.type)
 604         {
 605         case CreateNotify:
 606                 process_create_window_event(compositor, &event.xcreatewindow);
 607                 break;
 608         case DestroyNotify:
 609                 process_destroy_window_event(compositor, &event.xdestroywindow);
 610                 break;
 611         case MapNotify:
 612                 process_map_event(compositor, &event.xmap);
 613                 break;
 614         case UnmapNotify:
 615                 process_unmap_event(compositor, &event.xunmap);
 616                 break;
 617         case ReparentNotify:
 618                 process_reparent_event(compositor, &event.xreparent);
 619                 break;
 620         default:
 621                 if(event.type==compositor->damage_event+XDamageNotify)
 622                         process_damage_event(compositor, (XDamageNotifyEvent *)&event);
 623                 else
 624                         printf("Event %d\n", event.type);
 625         }
 626
 627         return 1;
 628 }
 629
 630 void refresh_screens(Compositor *compositor)
 631 {
 632         unsigned i, j;
 633
 634         for(i=0; i<compositor->nscreens; ++i)
 635         {
 636                 CompositedScreen *screen = &compositor->screens[i];
 637                 if(!screen->dirty)
 638                         continue;
 639
 640                 use_gl(compositor, screen);
 641
 642                 glClearColor(0.5f, 0.5f, 0.5f, 0.0f);
 643                 glClear(GL_COLOR_BUFFER_BIT);
 644
 645                 glUseProgram(screen->program);
 646                 glBindVertexArray(screen->vertex_array);
 647                 for(j=0; j<screen->nwindows; ++j)
 648                 {
 649                         CompositedWindow *window = &screen->windows[j];
 650                         if(window->map_state==IsViewable)
 651                         {
 652                                 glBindTexture(GL_TEXTURE_2D, window->texture);
 653                                 compositor->glXBindTexImageEXT(compositor->display, window->glx_pixmap, GLX_FRONT_LEFT_EXT, NULL);
 654                                 glUniform4f(screen->geometry_loc, (float)window->x/screen->width, (float)(screen->height-window->y-window->height)/screen->height, (float)(window->width+2*window->border)/screen->width, (float)(window->height+2*window->border)/screen->height);
 655                                 glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
 656                                 compositor->glXReleaseTexImageEXT(compositor->display, window->glx_pixmap, GLX_FRONT_LEFT_EXT);
 657                                 XDamageSubtract(compositor->display, window->damage, None, None);
 658                         }
 659                 }
 660                 glXSwapBuffers(compositor->display, screen->glx_window);
 661
 662                 screen->dirty = 0;
 663         }
 664
 665         compositor->dirty = 0;
 666 }
 667
 668 void sighandler(int sig)
 669 {
 670         terminate_requested = 1;
 671         (void)sig;
 672 }
 673
 674 int main()
 675 {
 676         Compositor compositor;
 677
 678         signal(SIGINT, &sighandler);
 679         signal(SIGTERM, &sighandler);
 680
 681         if(!initialize_compositor(&compositor))
 682                 return 1;
 683
 684         while(!terminate_requested)
 685         {
 686                 if(!process_event(&compositor))
 687                         refresh_screens(&compositor);
 688         }
 689
 690         shutdown_compositor(&compositor);
 691
 692         return 0;
 693 }