src/xdemos/pbdemo.c

   1
   2 /*
   3  * This program demonstrates how to do "off-screen" rendering using
   4  * the GLX pixel buffer extension.
   5  *
   6  * Written by Brian Paul for the "OpenGL and Window System Integration"
   7  * course presented at SIGGRAPH '97.  Updated on 5 October 2002.
   8  *
   9  * Usage:
  10  *   pbuffers width height imgfile
  11  * Where:
  12  *   width is the width, in pixels, of the image to generate.
  13  *   height is the height, in pixels, of the image to generate.
  14  *   imgfile is the name of the PPM image file to write.
  15  *
  16  *
  17  * This demo draws 3-D boxes with random orientation.  A pbuffer with
  18  * a depth (Z) buffer is prefered but if such a pbuffer can't be created
  19  * we use a non-depth-buffered config.
  20  *
  21  * On machines such as the SGI Indigo you may have to reconfigure your
  22  * display/X server to enable pbuffers.  Look in the /usr/gfx/ucode/MGRAS/vof/
  23  * directory for display configurationswith the _pbuf suffix.  Use
  24  * setmon -x <vof> to configure your X server and display for pbuffers.
  25  *
  26  * O2 systems seem to support pbuffers well.
  27  *
  28  * IR systems (at least 1RM systems) don't have single-buffered, RGBA,
  29  * Z-buffered pbuffer configs.  BUT, they DO have DOUBLE-buffered, RGBA,
  30  * Z-buffered pbuffers.  Note how we try four different fbconfig attribute
  31  * lists below!
  32  */
  33
  34
  35 #include <assert.h>
  36 #include <string.h>
  37 #include <stdio.h>
  38 #include <stdlib.h>
  39 #include <X11/Xlib.h>
  40 #include "pbutil.h"
  41
  42
  43 /* Some ugly global vars */
  44 static Display *gDpy = NULL;
  45 static int gScreen = 0;
  46 static FBCONFIG gFBconfig = 0;
  47 static PBUFFER gPBuffer = 0;
  48 static int gWidth, gHeight;
  49 static GLXContext glCtx;
  50
  51
  52
  53 /*
  54  * Create the pbuffer and return a GLXPbuffer handle.
  55  *
  56  * We loop over a list of fbconfigs trying to create
  57  * a pixel buffer.  We return the first pixel buffer which we successfully
  58  * create.
  59  */
  60 static PBUFFER
  61 MakePbuffer( Display *dpy, int screen, int width, int height )
  62 {
  63 #define NUM_FB_CONFIGS 4
  64    const char fbString[NUM_FB_CONFIGS][100] = {
  65       "Single Buffered, depth buffer",
  66       "Double Buffered, depth buffer",
  67       "Single Buffered, no depth buffer",
  68       "Double Buffered, no depth buffer"
  69    };
  70    int fbAttribs[NUM_FB_CONFIGS][100] = {
  71       {
  72          /* Single buffered, with depth buffer */
  73          GLX_RENDER_TYPE, GLX_RGBA_BIT,
  74          GLX_DRAWABLE_TYPE, GLX_PBUFFER_BIT,
  75          GLX_RED_SIZE, 1,
  76          GLX_GREEN_SIZE, 1,
  77          GLX_BLUE_SIZE, 1,
  78          GLX_DEPTH_SIZE, 1,
  79          GLX_DOUBLEBUFFER, 0,
  80          GLX_STENCIL_SIZE, 0,
  81          None
  82       },
  83       {
  84          /* Double buffered, with depth buffer */
  85          GLX_RENDER_TYPE, GLX_RGBA_BIT,
  86          GLX_DRAWABLE_TYPE, GLX_PBUFFER_BIT,
  87          GLX_RED_SIZE, 1,
  88          GLX_GREEN_SIZE, 1,
  89          GLX_BLUE_SIZE, 1,
  90          GLX_DEPTH_SIZE, 1,
  91          GLX_DOUBLEBUFFER, 1,
  92          GLX_STENCIL_SIZE, 0,
  93          None
  94       },
  95       {
  96          /* Single buffered, without depth buffer */
  97          GLX_RENDER_TYPE, GLX_RGBA_BIT,
  98          GLX_DRAWABLE_TYPE, GLX_PBUFFER_BIT,
  99          GLX_RED_SIZE, 1,
 100          GLX_GREEN_SIZE, 1,
 101          GLX_BLUE_SIZE, 1,
 102          GLX_DEPTH_SIZE, 0,
 103          GLX_DOUBLEBUFFER, 0,
 104          GLX_STENCIL_SIZE, 0,
 105          None
 106       },
 107       {
 108          /* Double buffered, without depth buffer */
 109          GLX_RENDER_TYPE, GLX_RGBA_BIT,
 110          GLX_DRAWABLE_TYPE, GLX_PBUFFER_BIT,
 111          GLX_RED_SIZE, 1,
 112          GLX_GREEN_SIZE, 1,
 113          GLX_BLUE_SIZE, 1,
 114          GLX_DEPTH_SIZE, 0,
 115          GLX_DOUBLEBUFFER, 1,
 116          GLX_STENCIL_SIZE, 0,
 117          None
 118       }
 119    };
 120    Bool largest = True;
 121    Bool preserve = False;
 122    FBCONFIG *fbConfigs;
 123    PBUFFER pBuffer = None;
 124    int nConfigs;
 125    int i;
 126    int attempt;
 127
 128    for (attempt=0; attempt<NUM_FB_CONFIGS; attempt++) {
 129
 130       /* Get list of possible frame buffer configurations */
 131       fbConfigs = ChooseFBConfig(dpy, screen, fbAttribs[attempt], &nConfigs);
 132       if (nConfigs==0 || !fbConfigs) {
 133          printf("Note: glXChooseFBConfig(%s) failed\n", fbString[attempt]);
 134          XFree(fbConfigs);
 135          continue;
 136       }
 137
 138 #if 0 /*DEBUG*/
 139       for (i=0;i<nConfigs;i++) {
 140          printf("Config %d\n", i);
 141          PrintFBConfigInfo(dpy, screen, fbConfigs[i], 0);
 142       }
 143 #endif
 144
 145       /* Create the pbuffer using first fbConfig in the list that works. */
 146       for (i=0;i<nConfigs;i++) {
 147          pBuffer = CreatePbuffer(dpy, screen, fbConfigs[i], width, height, largest, preserve);
 148          if (pBuffer) {
 149             gFBconfig = fbConfigs[i];
 150             gWidth = width;
 151             gHeight = height;
 152             break;
 153          }
 154       }
 155
 156       if (pBuffer!=None) {
 157          break;
 158       }
 159    }
 160
 161    if (pBuffer) {
 162       printf("Using: %s\n", fbString[attempt]);
 163    }
 164
 165    XFree(fbConfigs);
 166
 167    return pBuffer;
 168 #undef NUM_FB_CONFIGS
 169 }
 170
 171
 172
 173 /*
 174  * Do all the X / GLX setup stuff.
 175  */
 176 static int
 177 Setup(int width, int height)
 178 {
 179    int pbSupport;
 180    XVisualInfo *visInfo;
 181
 182    /* Open the X display */
 183    gDpy = XOpenDisplay(NULL);
 184    if (!gDpy) {
 185       printf("Error: couldn't open default X display.\n");
 186       return 0;
 187    }
 188
 189    /* Get default screen */
 190    gScreen = DefaultScreen(gDpy);
 191
 192    /* Test that pbuffers are available */
 193    pbSupport = QueryPbuffers(gDpy, gScreen);
 194    if (pbSupport == 1) {
 195       printf("Using GLX 1.3 Pbuffers\n");
 196    }
 197    else if (pbSupport == 2) {
 198       printf("Using SGIX Pbuffers\n");
 199    }
 200    else {
 201       printf("Error: pbuffers not available on this screen\n");
 202       XCloseDisplay(gDpy);
 203       return 0;
 204    }
 205
 206    /* Create Pbuffer */
 207    gPBuffer = MakePbuffer( gDpy, gScreen, width, height );
 208    if (gPBuffer==None) {
 209       printf("Error: couldn't create pbuffer\n");
 210       XCloseDisplay(gDpy);
 211       return 0;
 212    }
 213
 214    /* Test drawable queries */
 215    {
 216       unsigned int v;
 217       glXQueryDrawable( gDpy, gPBuffer, GLX_WIDTH, &v);
 218       printf("GLX_WIDTH = %u\n", v);
 219       glXQueryDrawable( gDpy, gPBuffer, GLX_HEIGHT, &v);
 220       printf("GLX_HEIGHT = %u\n", v);
 221       glXQueryDrawable( gDpy, gPBuffer, GLX_PRESERVED_CONTENTS, &v);
 222       printf("GLX_PRESERVED_CONTENTS = %u\n", v);
 223       glXQueryDrawable( gDpy, gPBuffer, GLX_LARGEST_PBUFFER, &v);
 224       printf("GLX_LARGEST_PBUFFER = %u\n", v);
 225       glXQueryDrawable( gDpy, gPBuffer, GLX_FBCONFIG_ID, &v);
 226       printf("GLX_FBCONFIG_ID = %u\n", v);
 227    }
 228
 229    /* Get corresponding XVisualInfo */
 230    visInfo = GetVisualFromFBConfig(gDpy, gScreen, gFBconfig);
 231    if (!visInfo) {
 232       printf("Error: can't get XVisualInfo from FBconfig\n");
 233       XCloseDisplay(gDpy);
 234       return 0;
 235    }
 236
 237    /* Create GLX context */
 238    glCtx = glXCreateContext(gDpy, visInfo, NULL, True);
 239    if (!glCtx) {
 240       /* try indirect */
 241       glCtx = glXCreateContext(gDpy, visInfo, NULL, False);
 242       if (!glCtx) {
 243          printf("Error: Couldn't create GLXContext\n");
 244          XFree(visInfo);
 245          XCloseDisplay(gDpy);
 246          return 0;
 247       }
 248       else {
 249          printf("Warning: using indirect GLXContext\n");
 250       }
 251    }
 252
 253    /* Bind context to pbuffer */
 254    if (!glXMakeCurrent(gDpy, gPBuffer, glCtx)) {
 255       printf("Error: glXMakeCurrent failed\n");
 256       XFree(visInfo);
 257       XCloseDisplay(gDpy);
 258       return 0;
 259    }
 260
 261    return 1;  /* Success!! */
 262 }
 263
 264
 265
 266 /* One-time GL setup */
 267 static void
 268 InitGL(void)
 269 {
 270    static GLfloat pos[4] = {0.0, 0.0, 10.0, 0.0};
 271    glEnable(GL_LIGHTING);
 272    glEnable(GL_LIGHT0);
 273    glLightfv(GL_LIGHT0, GL_POSITION, pos);
 274    glEnable(GL_NORMALIZE);
 275    glEnable(GL_DEPTH_TEST);
 276    glEnable(GL_CULL_FACE);
 277
 278    glViewport(0, 0, gWidth, gHeight);
 279    glMatrixMode( GL_PROJECTION );
 280    glLoadIdentity();
 281    glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
 282    glMatrixMode( GL_MODELVIEW );
 283    glLoadIdentity();
 284    glTranslatef( 0.0, 0.0, -15.0 );
 285 }
 286
 287
 288 /* Return random float in [0,1] */
 289 static float
 290 Random(void)
 291 {
 292    int i = rand();
 293    return (float) (i % 1000) / 1000.0;
 294 }
 295
 296
 297 static void
 298 RandomColor(void)
 299 {
 300    GLfloat c[4];
 301    c[0] = Random();
 302    c[1] = Random();
 303    c[2] = Random();
 304    c[3] = 1.0;
 305    glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, c);
 306 }
 307
 308
 309 /* This function borrowed from Mark Kilgard's GLUT */
 310 static void
 311 drawBox(GLfloat x0, GLfloat x1, GLfloat y0, GLfloat y1,
 312   GLfloat z0, GLfloat z1, GLenum type)
 313 {
 314   static GLfloat n[6][3] =
 315   {
 316     {-1.0, 0.0, 0.0},
 317     {0.0, 1.0, 0.0},
 318     {1.0, 0.0, 0.0},
 319     {0.0, -1.0, 0.0},
 320     {0.0, 0.0, 1.0},
 321     {0.0, 0.0, -1.0}
 322   };
 323   static GLint faces[6][4] =
 324   {
 325     {0, 1, 2, 3},
 326     {3, 2, 6, 7},
 327     {7, 6, 5, 4},
 328     {4, 5, 1, 0},
 329     {5, 6, 2, 1},
 330     {7, 4, 0, 3}
 331   };
 332   GLfloat v[8][3], tmp;
 333   GLint i;
 334
 335   if (x0 > x1) {
 336     tmp = x0;
 337     x0 = x1;
 338     x1 = tmp;
 339   }
 340   if (y0 > y1) {
 341     tmp = y0;
 342     y0 = y1;
 343     y1 = tmp;
 344   }
 345   if (z0 > z1) {
 346     tmp = z0;
 347     z0 = z1;
 348     z1 = tmp;
 349   }
 350   v[0][0] = v[1][0] = v[2][0] = v[3][0] = x0;
 351   v[4][0] = v[5][0] = v[6][0] = v[7][0] = x1;
 352   v[0][1] = v[1][1] = v[4][1] = v[5][1] = y0;
 353   v[2][1] = v[3][1] = v[6][1] = v[7][1] = y1;
 354   v[0][2] = v[3][2] = v[4][2] = v[7][2] = z0;
 355   v[1][2] = v[2][2] = v[5][2] = v[6][2] = z1;
 356
 357   for (i = 0; i < 6; i++) {
 358     glBegin(type);
 359     glNormal3fv(&n[i][0]);
 360     glVertex3fv(&v[faces[i][0]][0]);
 361     glVertex3fv(&v[faces[i][1]][0]);
 362     glVertex3fv(&v[faces[i][2]][0]);
 363     glVertex3fv(&v[faces[i][3]][0]);
 364     glEnd();
 365   }
 366 }
 367
 368
 369
 370 /* Render a scene */
 371 static void
 372 Render(void)
 373 {
 374    int NumBoxes = 100;
 375    int i;
 376
 377    glClearColor(0.2, 0.2, 0.9, 0.0);
 378    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 379
 380    for (i=0;i<NumBoxes;i++) {
 381       float tx = -2.0 + 4.0 * Random();
 382       float ty = -2.0 + 4.0 * Random();
 383       float tz =  4.0 - 16.0 * Random();
 384       float sx = 0.1 + Random() * 0.4;
 385       float sy = 0.1 + Random() * 0.4;
 386       float sz = 0.1 + Random() * 0.4;
 387       float rx = Random();
 388       float ry = Random();
 389       float rz = Random();
 390       float ra = Random() * 360.0;
 391       glPushMatrix();
 392       glTranslatef(tx, ty, tz);
 393       glRotatef(ra, rx, ry, rz);
 394       glScalef(sx, sy, sz);
 395       RandomColor();
 396       drawBox(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0, GL_POLYGON);
 397       glPopMatrix();
 398    }
 399
 400    glFinish();
 401 }
 402
 403
 404
 405 static void
 406 WriteFile(const char *filename)
 407 {
 408    FILE *f;
 409    GLubyte *image;
 410    int i;
 411
 412    image = malloc(gWidth * gHeight * 3 * sizeof(GLubyte));
 413    if (!image) {
 414       printf("Error: couldn't allocate image buffer\n");
 415       return;
 416    }
 417
 418    glPixelStorei(GL_PACK_ALIGNMENT, 1);
 419    glReadPixels(0, 0, gWidth, gHeight, GL_RGB, GL_UNSIGNED_BYTE, image);
 420
 421    f = fopen(filename, "w");
 422    if (!f) {
 423       printf("Couldn't open image file: %s\n", filename);
 424       return;
 425    }
 426    fprintf(f,"P6\n");
 427    fprintf(f,"# ppm-file created by %s\n", "trdemo2");
 428    fprintf(f,"%i %i\n", gWidth, gHeight);
 429    fprintf(f,"255\n");
 430    fclose(f);
 431    f = fopen(filename, "ab");  /* now append binary data */
 432    if (!f) {
 433       printf("Couldn't append to image file: %s\n", filename);
 434       return;
 435    }
 436
 437    for (i=0;i<gHeight;i++) {
 438       GLubyte *rowPtr;
 439       /* Remember, OpenGL images are bottom to top.  Have to reverse. */
 440       rowPtr = image + (gHeight-1-i) * gWidth*3;
 441       fwrite(rowPtr, 1, gWidth*3, f);
 442    }
 443
 444    fclose(f);
 445    free(image);
 446
 447    printf("Wrote %d by %d image file: %s\n", gWidth, gHeight, filename);
 448 }
 449
 450
 451
 452 /*
 453  * Print message describing command line parameters.
 454  */
 455 static void
 456 Usage(const char *appName)
 457 {
 458    printf("Usage:\n");
 459    printf("  %s width height imgfile\n", appName);
 460    printf("Where imgfile is a ppm file\n");
 461 }
 462
 463
 464
 465 int
 466 main(int argc, char *argv[])
 467 {
 468    if (argc!=4) {
 469       Usage(argv[0]);
 470    }
 471    else {
 472       int width = atoi(argv[1]);
 473       int height = atoi(argv[2]);
 474       char *fileName = argv[3];
 475       if (width<=0) {
 476          printf("Error: width parameter must be at least 1.\n");
 477          return 1;
 478       }
 479       if (height<=0) {
 480          printf("Error: height parameter must be at least 1.\n");
 481          return 1;
 482       }
 483       if (!Setup(width, height)) {
 484          return 1;
 485       }
 486       InitGL();
 487       Render();
 488       WriteFile(fileName);
 489       DestroyPbuffer(gDpy, gScreen, gPBuffer);
 490    }
 491    return 0;
 492 }
 493