progs/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          continue;
 135       }
 136
 137 #if 0 /*DEBUG*/
 138       for (i=0;i<nConfigs;i++) {
 139          printf("Config %d\n", i);
 140          PrintFBConfigInfo(dpy, screen, fbConfigs[i], 0);
 141       }
 142 #endif
 143
 144       /* Create the pbuffer using first fbConfig in the list that works. */
 145       for (i=0;i<nConfigs;i++) {
 146          pBuffer = CreatePbuffer(dpy, screen, fbConfigs[i], width, height, preserve, largest);
 147          if (pBuffer) {
 148             gFBconfig = fbConfigs[i];
 149             gWidth = width;
 150             gHeight = height;
 151             break;
 152          }
 153       }
 154
 155       if (pBuffer!=None) {
 156          break;
 157       }
 158    }
 159
 160    if (pBuffer) {
 161       printf("Using: %s\n", fbString[attempt]);
 162    }
 163
 164    XFree(fbConfigs);
 165
 166    return pBuffer;
 167 #undef NUM_FB_CONFIGS
 168 }
 169
 170
 171
 172 /*
 173  * Do all the X / GLX setup stuff.
 174  */
 175 static int
 176 Setup(int width, int height)
 177 {
 178    int pbSupport;
 179    XVisualInfo *visInfo;
 180
 181    /* Open the X display */
 182    gDpy = XOpenDisplay(NULL);
 183    if (!gDpy) {
 184       printf("Error: couldn't open default X display.\n");
 185       return 0;
 186    }
 187
 188    /* Get default screen */
 189    gScreen = DefaultScreen(gDpy);
 190
 191    /* Test that pbuffers are available */
 192    pbSupport = QueryPbuffers(gDpy, gScreen);
 193    if (pbSupport == 1) {
 194       printf("Using GLX 1.3 Pbuffers\n");
 195    }
 196    else if (pbSupport == 2) {
 197       printf("Using SGIX Pbuffers\n");
 198    }
 199    else {
 200       printf("Error: pbuffers not available on this screen\n");
 201       XCloseDisplay(gDpy);
 202       return 0;
 203    }
 204
 205    /* Create Pbuffer */
 206    gPBuffer = MakePbuffer( gDpy, gScreen, width, height );
 207    if (gPBuffer==None) {
 208       printf("Error: couldn't create pbuffer\n");
 209       XCloseDisplay(gDpy);
 210       return 0;
 211    }
 212
 213    /* Get corresponding XVisualInfo */
 214    visInfo = GetVisualFromFBConfig(gDpy, gScreen, gFBconfig);
 215    if (!visInfo) {
 216       printf("Error: can't get XVisualInfo from FBconfig\n");
 217       XCloseDisplay(gDpy);
 218       return 0;
 219    }
 220
 221    /* Create GLX context */
 222    glCtx = glXCreateContext(gDpy, visInfo, NULL, True);
 223    if (!glCtx) {
 224       /* try indirect */
 225       glCtx = glXCreateContext(gDpy, visInfo, NULL, False);
 226       if (!glCtx) {
 227          printf("Error: Couldn't create GLXContext\n");
 228          XFree(visInfo);
 229          XCloseDisplay(gDpy);
 230          return 0;
 231       }
 232       else {
 233          printf("Warning: using indirect GLXContext\n");
 234       }
 235    }
 236
 237    /* Bind context to pbuffer */
 238    if (!glXMakeCurrent(gDpy, gPBuffer, glCtx)) {
 239       printf("Error: glXMakeCurrent failed\n");
 240       XFree(visInfo);
 241       XCloseDisplay(gDpy);
 242       return 0;
 243    }
 244
 245    return 1;  /* Success!! */
 246 }
 247
 248
 249
 250 /* One-time GL setup */
 251 static void
 252 InitGL(void)
 253 {
 254    static GLfloat pos[4] = {0.0, 0.0, 10.0, 0.0};
 255    glEnable(GL_LIGHTING);
 256    glEnable(GL_LIGHT0);
 257    glLightfv(GL_LIGHT0, GL_POSITION, pos);
 258    glEnable(GL_NORMALIZE);
 259    glEnable(GL_DEPTH_TEST);
 260    glEnable(GL_CULL_FACE);
 261
 262    glViewport(0, 0, gWidth, gHeight);
 263    glMatrixMode( GL_PROJECTION );
 264    glLoadIdentity();
 265    glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
 266    glMatrixMode( GL_MODELVIEW );
 267    glLoadIdentity();
 268    glTranslatef( 0.0, 0.0, -15.0 );
 269 }
 270
 271
 272 /* Return random float in [0,1] */
 273 static float
 274 Random(void)
 275 {
 276    int i = rand();
 277    return (float) (i % 1000) / 1000.0;
 278 }
 279
 280
 281 static void
 282 RandomColor(void)
 283 {
 284    GLfloat c[4];
 285    c[0] = Random();
 286    c[1] = Random();
 287    c[2] = Random();
 288    c[3] = 1.0;
 289    glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, c);
 290 }
 291
 292
 293 /* This function borrowed from Mark Kilgard's GLUT */
 294 static void
 295 drawBox(GLfloat x0, GLfloat x1, GLfloat y0, GLfloat y1,
 296   GLfloat z0, GLfloat z1, GLenum type)
 297 {
 298   static GLfloat n[6][3] =
 299   {
 300     {-1.0, 0.0, 0.0},
 301     {0.0, 1.0, 0.0},
 302     {1.0, 0.0, 0.0},
 303     {0.0, -1.0, 0.0},
 304     {0.0, 0.0, 1.0},
 305     {0.0, 0.0, -1.0}
 306   };
 307   static GLint faces[6][4] =
 308   {
 309     {0, 1, 2, 3},
 310     {3, 2, 6, 7},
 311     {7, 6, 5, 4},
 312     {4, 5, 1, 0},
 313     {5, 6, 2, 1},
 314     {7, 4, 0, 3}
 315   };
 316   GLfloat v[8][3], tmp;
 317   GLint i;
 318
 319   if (x0 > x1) {
 320     tmp = x0;
 321     x0 = x1;
 322     x1 = tmp;
 323   }
 324   if (y0 > y1) {
 325     tmp = y0;
 326     y0 = y1;
 327     y1 = tmp;
 328   }
 329   if (z0 > z1) {
 330     tmp = z0;
 331     z0 = z1;
 332     z1 = tmp;
 333   }
 334   v[0][0] = v[1][0] = v[2][0] = v[3][0] = x0;
 335   v[4][0] = v[5][0] = v[6][0] = v[7][0] = x1;
 336   v[0][1] = v[1][1] = v[4][1] = v[5][1] = y0;
 337   v[2][1] = v[3][1] = v[6][1] = v[7][1] = y1;
 338   v[0][2] = v[3][2] = v[4][2] = v[7][2] = z0;
 339   v[1][2] = v[2][2] = v[5][2] = v[6][2] = z1;
 340
 341   for (i = 0; i < 6; i++) {
 342     glBegin(type);
 343     glNormal3fv(&n[i][0]);
 344     glVertex3fv(&v[faces[i][0]][0]);
 345     glVertex3fv(&v[faces[i][1]][0]);
 346     glVertex3fv(&v[faces[i][2]][0]);
 347     glVertex3fv(&v[faces[i][3]][0]);
 348     glEnd();
 349   }
 350 }
 351
 352
 353
 354 /* Render a scene */
 355 static void
 356 Render(void)
 357 {
 358    int NumBoxes = 100;
 359    int i;
 360
 361    glClearColor(0.2, 0.2, 0.9, 0.0);
 362    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 363
 364    for (i=0;i<NumBoxes;i++) {
 365       float tx = -2.0 + 4.0 * Random();
 366       float ty = -2.0 + 4.0 * Random();
 367       float tz =  4.0 - 16.0 * Random();
 368       float sx = 0.1 + Random() * 0.4;
 369       float sy = 0.1 + Random() * 0.4;
 370       float sz = 0.1 + Random() * 0.4;
 371       float rx = Random();
 372       float ry = Random();
 373       float rz = Random();
 374       float ra = Random() * 360.0;
 375       glPushMatrix();
 376       glTranslatef(tx, ty, tz);
 377       glRotatef(ra, rx, ry, rz);
 378       glScalef(sx, sy, sz);
 379       RandomColor();
 380       drawBox(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0, GL_POLYGON);
 381       glPopMatrix();
 382    }
 383
 384    glFinish();
 385 }
 386
 387
 388
 389 static void
 390 WriteFile(const char *filename)
 391 {
 392    FILE *f;
 393    GLubyte *image;
 394    int i;
 395
 396    image = malloc(gWidth * gHeight * 3 * sizeof(GLubyte));
 397    if (!image) {
 398       printf("Error: couldn't allocate image buffer\n");
 399       return;
 400    }
 401
 402    glPixelStorei(GL_PACK_ALIGNMENT, 1);
 403    glReadPixels(0, 0, gWidth, gHeight, GL_RGB, GL_UNSIGNED_BYTE, image);
 404
 405    f = fopen(filename, "w");
 406    if (!f) {
 407       printf("Couldn't open image file: %s\n", filename);
 408       return;
 409    }
 410    fprintf(f,"P6\n");
 411    fprintf(f,"# ppm-file created by %s\n", "trdemo2");
 412    fprintf(f,"%i %i\n", gWidth, gHeight);
 413    fprintf(f,"255\n");
 414    fclose(f);
 415    f = fopen(filename, "ab");  /* now append binary data */
 416    if (!f) {
 417       printf("Couldn't append to image file: %s\n", filename);
 418       return;
 419    }
 420
 421    for (i=0;i<gHeight;i++) {
 422       GLubyte *rowPtr;
 423       /* Remember, OpenGL images are bottom to top.  Have to reverse. */
 424       rowPtr = image + (gHeight-1-i) * gWidth*3;
 425       fwrite(rowPtr, 1, gWidth*3, f);
 426    }
 427
 428    fclose(f);
 429    free(image);
 430
 431    printf("Wrote %d by %d image file: %s\n", gWidth, gHeight, filename);
 432 }
 433
 434
 435
 436 /*
 437  * Print message describing command line parameters.
 438  */
 439 static void
 440 Usage(const char *appName)
 441 {
 442    printf("Usage:\n");
 443    printf("  %s width height imgfile\n", appName);
 444    printf("Where imgfile is a ppm file\n");
 445 }
 446
 447
 448
 449 int
 450 main(int argc, char *argv[])
 451 {
 452    if (argc!=4) {
 453       Usage(argv[0]);
 454    }
 455    else {
 456       int width = atoi(argv[1]);
 457       int height = atoi(argv[2]);
 458       char *fileName = argv[3];
 459       if (width<=0) {
 460          printf("Error: width parameter must be at least 1.\n");
 461          return 1;
 462       }
 463       if (height<=0) {
 464          printf("Error: height parameter must be at least 1.\n");
 465          return 1;
 466       }
 467       if (!Setup(width, height)) {
 468          return 1;
 469       }
 470       InitGL();
 471       Render();
 472       WriteFile(fileName);
 473       DestroyPbuffer(gDpy, gScreen, gPBuffer);
 474    }
 475    return 0;
 476 }
 477