progs/xdemos/glxpbdemo.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  * Updated on 31 January 2004 to use native GLX by
  10  * Andrew P. Lentvorski, Jr. <bsder@allcaps.org>
  11  *
  12  * Usage:
  13  *   glxpbdemo width height imgfile
  14  * Where:
  15  *   width is the width, in pixels, of the image to generate.
  16  *   height is the height, in pixels, of the image to generate.
  17  *   imgfile is the name of the PPM image file to write.
  18  *
  19  *
  20  * This demo draws 3-D boxes with random orientation.
  21  *
  22  * On machines such as the SGI Indigo you may have to reconfigure your
  23  * display/X server to enable pbuffers.  Look in the /usr/gfx/ucode/MGRAS/vof/
  24  * directory for display configurations with the _pbuf suffix.  Use
  25  * setmon -x <vof> to configure your X server and display for pbuffers.
  26  *
  27  * O2 systems seem to support pbuffers well.
  28  *
  29  */
  30
  31 #include <string.h>
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #include <X11/Xlib.h>
  35 #include <GL/glx.h>
  36
  37 /* Some ugly global vars */
  38 static GLXFBConfig gFBconfig = 0;
  39 static Display *gDpy = NULL;
  40 static int gScreen = 0;
  41 static GLXPbuffer gPBuffer = 0;
  42 static int gWidth, gHeight;
  43
  44
  45 /*
  46  * Test for appropriate version of GLX to run this program
  47  * Input:  dpy - the X display
  48  *         screen - screen number
  49  * Return:  0 = GLX not available.
  50  *          1 = GLX available.
  51  */
  52 static int
  53 RuntimeQueryGLXVersion(Display *dpy, int screen)
  54 {
  55 #if defined(GLX_VERSION_1_3) || defined(GLX_VERSION_1_4)
  56    char *glxversion;
  57
  58    glxversion = (char *) glXGetClientString(dpy, GLX_VERSION);
  59    if (!(strstr(glxversion, "1.3") || strstr(glxversion, "1.4")))
  60       return 0;
  61
  62    glxversion = (char *) glXQueryServerString(dpy, screen, GLX_VERSION);
  63    if (!(strstr(glxversion, "1.3") || strstr(glxversion, "1.4")))
  64       return 0;
  65
  66    return 1;
  67 #else
  68    return 0;
  69 #endif
  70 }
  71
  72
  73
  74 /*
  75  * Create the pbuffer and return a GLXPbuffer handle.
  76  */
  77 static GLXPbuffer
  78 MakePbuffer( Display *dpy, int screen, int width, int height )
  79 {
  80    GLXFBConfig *fbConfigs;
  81    GLXFBConfig chosenFBConfig;
  82    GLXPbuffer pBuffer = None;
  83
  84    int nConfigs;
  85    int fbconfigid;
  86
  87    int fbAttribs[] = {
  88       GLX_RENDER_TYPE, GLX_RGBA_BIT,
  89       GLX_DEPTH_SIZE, 1,
  90       GLX_DRAWABLE_TYPE, GLX_PIXMAP_BIT | GLX_PBUFFER_BIT,
  91       None
  92    };
  93
  94    int pbAttribs[] = {
  95       GLX_PBUFFER_WIDTH, 0,
  96       GLX_PBUFFER_HEIGHT, 0,
  97       GLX_LARGEST_PBUFFER, False,
  98       GLX_PRESERVED_CONTENTS, False,
  99       None
 100    };
 101
 102    pbAttribs[1] = width;
 103    pbAttribs[3] = height;
 104
 105    fbConfigs = glXChooseFBConfig(dpy, screen, fbAttribs, &nConfigs);
 106
 107    if (0 == nConfigs || !fbConfigs) {
 108       printf("Error: glxChooseFBConfig failed\n");
 109       XFree(fbConfigs);
 110       XCloseDisplay(dpy);
 111       return 0;
 112    }
 113
 114    chosenFBConfig = fbConfigs[0];
 115
 116    glXGetFBConfigAttrib(dpy, chosenFBConfig, GLX_FBCONFIG_ID, &fbconfigid);
 117    printf("Chose 0x%x as fbconfigid\n", fbconfigid);
 118
 119    /* Create the pbuffer using first fbConfig in the list that works. */
 120    pBuffer = glXCreatePbuffer(dpy, chosenFBConfig, pbAttribs);
 121
 122    if (pBuffer) {
 123       gFBconfig = chosenFBConfig;
 124       gWidth = width;
 125       gHeight = height;
 126    }
 127
 128    XFree(fbConfigs);
 129
 130    return pBuffer;
 131 }
 132
 133
 134
 135 /*
 136  * Do all the X / GLX setup stuff.
 137  */
 138 static int
 139 Setup(int width, int height)
 140 {
 141 #if defined(GLX_VERSION_1_3) || defined(GLX_VERSION_1_4)
 142    GLXContext glCtx;
 143
 144    /* Open the X display */
 145    gDpy = XOpenDisplay(NULL);
 146    if (!gDpy) {
 147       printf("Error: couldn't open default X display.\n");
 148       return 0;
 149    }
 150
 151    /* Get default screen */
 152    gScreen = DefaultScreen(gDpy);
 153
 154    /* Test that GLX is available */
 155    if (!RuntimeQueryGLXVersion(gDpy, gScreen)) {
 156      printf("Error: GLX 1.3 or 1.4 not available\n");
 157      XCloseDisplay(gDpy);
 158      return 0;
 159    }
 160
 161    /* Create Pbuffer */
 162    gPBuffer = MakePbuffer( gDpy, gScreen, width, height );
 163    if (gPBuffer==None) {
 164       printf("Error: couldn't create pbuffer\n");
 165       XCloseDisplay(gDpy);
 166       return 0;
 167    }
 168
 169    /* Create GLX context */
 170    glCtx = glXCreateNewContext(gDpy, gFBconfig, GLX_RGBA_TYPE, NULL, True);
 171    if (glCtx) {
 172       if (!glXIsDirect(gDpy, glCtx)) {
 173          printf("Warning: using indirect GLXContext\n");
 174       }
 175    }
 176    else {
 177       printf("Error: Couldn't create GLXContext\n");
 178       XCloseDisplay(gDpy);
 179       return 0;
 180    }
 181
 182    /* Bind context to pbuffer */
 183    if (!glXMakeCurrent(gDpy, gPBuffer, glCtx)) {
 184       printf("Error: glXMakeCurrent failed\n");
 185       XCloseDisplay(gDpy);
 186       return 0;
 187    }
 188
 189    return 1;  /* Success!! */
 190 #else
 191    printf("Error: GLX version 1.3 or 1.4 not available at compile time\n");
 192    return 0;
 193 #endif
 194 }
 195
 196
 197
 198 /* One-time GL setup */
 199 static void
 200 InitGL(void)
 201 {
 202    static GLfloat pos[4] = {0.0, 0.0, 10.0, 0.0};
 203    glEnable(GL_LIGHTING);
 204    glEnable(GL_LIGHT0);
 205    glLightfv(GL_LIGHT0, GL_POSITION, pos);
 206    glEnable(GL_NORMALIZE);
 207    glEnable(GL_DEPTH_TEST);
 208    glEnable(GL_CULL_FACE);
 209
 210    glViewport(0, 0, gWidth, gHeight);
 211    glMatrixMode( GL_PROJECTION );
 212    glLoadIdentity();
 213    glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
 214    glMatrixMode( GL_MODELVIEW );
 215    glLoadIdentity();
 216    glTranslatef( 0.0, 0.0, -15.0 );
 217
 218 }
 219
 220
 221 /* Return random float in [0,1] */
 222 static float
 223 Random(void)
 224 {
 225    int i = rand();
 226    return (float) (i % 1000) / 1000.0;
 227 }
 228
 229
 230 static void
 231 RandomColor(void)
 232 {
 233    GLfloat c[4];
 234    c[0] = Random();
 235    c[1] = Random();
 236    c[2] = Random();
 237    c[3] = 1.0;
 238    glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, c);
 239 }
 240
 241
 242 /* This function borrowed from Mark Kilgard's GLUT */
 243 static void
 244 drawBox(GLfloat x0, GLfloat x1, GLfloat y0, GLfloat y1,
 245         GLfloat z0, GLfloat z1, GLenum type)
 246 {
 247   static GLfloat n[6][3] =
 248   {
 249     {-1.0, 0.0, 0.0},
 250     {0.0, 1.0, 0.0},
 251     {1.0, 0.0, 0.0},
 252     {0.0, -1.0, 0.0},
 253     {0.0, 0.0, 1.0},
 254     {0.0, 0.0, -1.0}
 255   };
 256   static GLint faces[6][4] =
 257   {
 258     {0, 1, 2, 3},
 259     {3, 2, 6, 7},
 260     {7, 6, 5, 4},
 261     {4, 5, 1, 0},
 262     {5, 6, 2, 1},
 263     {7, 4, 0, 3}
 264   };
 265   GLfloat v[8][3], tmp;
 266   GLint i;
 267
 268   if (x0 > x1) {
 269     tmp = x0;
 270     x0 = x1;
 271     x1 = tmp;
 272   }
 273   if (y0 > y1) {
 274     tmp = y0;
 275     y0 = y1;
 276     y1 = tmp;
 277   }
 278   if (z0 > z1) {
 279     tmp = z0;
 280     z0 = z1;
 281     z1 = tmp;
 282   }
 283   v[0][0] = v[1][0] = v[2][0] = v[3][0] = x0;
 284   v[4][0] = v[5][0] = v[6][0] = v[7][0] = x1;
 285   v[0][1] = v[1][1] = v[4][1] = v[5][1] = y0;
 286   v[2][1] = v[3][1] = v[6][1] = v[7][1] = y1;
 287   v[0][2] = v[3][2] = v[4][2] = v[7][2] = z0;
 288   v[1][2] = v[2][2] = v[5][2] = v[6][2] = z1;
 289
 290   for (i = 0; i < 6; i++) {
 291     glBegin(type);
 292     glNormal3fv(&n[i][0]);
 293     glVertex3fv(&v[faces[i][0]][0]);
 294     glVertex3fv(&v[faces[i][1]][0]);
 295     glVertex3fv(&v[faces[i][2]][0]);
 296     glVertex3fv(&v[faces[i][3]][0]);
 297     glEnd();
 298   }
 299 }
 300
 301
 302
 303 /* Render a scene */
 304 static void
 305 Render(void)
 306 {
 307    int NumBoxes = 100;
 308    int i;
 309
 310    InitGL();
 311    glClearColor(0.2, 0.2, 0.9, 0.0);
 312    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 313
 314    for (i=0;i<NumBoxes;i++) {
 315       float tx = -2.0 + 4.0 * Random();
 316       float ty = -2.0 + 4.0 * Random();
 317       float tz =  4.0 - 16.0 * Random();
 318       float sx = 0.1 + Random() * 0.4;
 319       float sy = 0.1 + Random() * 0.4;
 320       float sz = 0.1 + Random() * 0.4;
 321       float rx = Random();
 322       float ry = Random();
 323       float rz = Random();
 324       float ra = Random() * 360.0;
 325       glPushMatrix();
 326       glTranslatef(tx, ty, tz);
 327       glRotatef(ra, rx, ry, rz);
 328       glScalef(sx, sy, sz);
 329       RandomColor();
 330       drawBox(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0, GL_POLYGON);
 331       glPopMatrix();
 332    }
 333
 334    glFinish();
 335 }
 336
 337
 338
 339 static void
 340 WriteFile(const char *filename)
 341 {
 342    FILE *f;
 343    GLubyte *image;
 344    int i;
 345
 346    image = malloc(gWidth * gHeight * 3 * sizeof(GLubyte));
 347    if (!image) {
 348       printf("Error: couldn't allocate image buffer\n");
 349       return;
 350    }
 351
 352    glPixelStorei(GL_PACK_ALIGNMENT, 1);
 353    glReadPixels(0, 0, gWidth, gHeight, GL_RGB, GL_UNSIGNED_BYTE, image);
 354
 355    f = fopen(filename, "w");
 356    if (!f) {
 357       printf("Couldn't open image file: %s\n", filename);
 358       return;
 359    }
 360    fprintf(f,"P6\n");
 361    fprintf(f,"# ppm-file created by %s\n", "trdemo2");
 362    fprintf(f,"%i %i\n", gWidth, gHeight);
 363    fprintf(f,"255\n");
 364    fclose(f);
 365    f = fopen(filename, "ab");  /* now append binary data */
 366    if (!f) {
 367       printf("Couldn't append to image file: %s\n", filename);
 368       return;
 369    }
 370
 371    for (i=0;i<gHeight;i++) {
 372       GLubyte *rowPtr;
 373       /* Remember, OpenGL images are bottom to top.  Have to reverse. */
 374       rowPtr = image + (gHeight-1-i) * gWidth*3;
 375       fwrite(rowPtr, 1, gWidth*3, f);
 376    }
 377
 378    fclose(f);
 379    free(image);
 380
 381    printf("Wrote %d by %d image file: %s\n", gWidth, gHeight, filename);
 382 }
 383
 384
 385
 386 /*
 387  * Print message describing command line parameters.
 388  */
 389 static void
 390 Usage(const char *appName)
 391 {
 392    printf("Usage:\n");
 393    printf("  %s width height imgfile\n", appName);
 394    printf("Where imgfile is a ppm file\n");
 395 }
 396
 397
 398
 399 int
 400 main(int argc, char *argv[])
 401 {
 402    if (argc!=4) {
 403       Usage(argv[0]);
 404    }
 405    else {
 406       int width = atoi(argv[1]);
 407       int height = atoi(argv[2]);
 408       char *fileName = argv[3];
 409       if (width<=0) {
 410          printf("Error: width parameter must be at least 1.\n");
 411          return 1;
 412       }
 413       if (height<=0) {
 414          printf("Error: height parameter must be at least 1.\n");
 415          return 1;
 416       }
 417       if (!Setup(width, height)) {
 418          return 1;
 419       }
 420
 421       printf("Setup completed\n");
 422       Render();
 423       printf("Render completed.\n");
 424       WriteFile(fileName);
 425       printf("File write completed.\n");
 426
 427       glXDestroyPbuffer( gDpy, gPBuffer );
 428    }
 429    return 0;
 430 }
 431