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       XCloseDisplay(dpy);
 110       return 0;
 111    }
 112
 113    chosenFBConfig = fbConfigs[0];
 114
 115    glXGetFBConfigAttrib(dpy, chosenFBConfig, GLX_FBCONFIG_ID, &fbconfigid);
 116    printf("Chose 0x%x as fbconfigid\n", fbconfigid);
 117
 118    /* Create the pbuffer using first fbConfig in the list that works. */
 119    pBuffer = glXCreatePbuffer(dpy, chosenFBConfig, pbAttribs);
 120
 121    if (pBuffer) {
 122       gFBconfig = chosenFBConfig;
 123       gWidth = width;
 124       gHeight = height;
 125    }
 126
 127    XFree(fbConfigs);
 128
 129    return pBuffer;
 130 }
 131
 132
 133
 134 /*
 135  * Do all the X / GLX setup stuff.
 136  */
 137 static int
 138 Setup(int width, int height)
 139 {
 140 #if defined(GLX_VERSION_1_3) || defined(GLX_VERSION_1_4)
 141    GLXContext glCtx;
 142
 143    /* Open the X display */
 144    gDpy = XOpenDisplay(NULL);
 145    if (!gDpy) {
 146       printf("Error: couldn't open default X display.\n");
 147       return 0;
 148    }
 149
 150    /* Get default screen */
 151    gScreen = DefaultScreen(gDpy);
 152
 153    /* Test that GLX is available */
 154    if (!RuntimeQueryGLXVersion(gDpy, gScreen)) {
 155      printf("Error: GLX 1.3 or 1.4 not available\n");
 156      XCloseDisplay(gDpy);
 157      return 0;
 158    }
 159
 160    /* Create Pbuffer */
 161    gPBuffer = MakePbuffer( gDpy, gScreen, width, height );
 162    if (gPBuffer==None) {
 163       printf("Error: couldn't create pbuffer\n");
 164       XCloseDisplay(gDpy);
 165       return 0;
 166    }
 167
 168    /* Create GLX context */
 169    glCtx = glXCreateNewContext(gDpy, gFBconfig, GLX_RGBA_TYPE, NULL, True);
 170    if (glCtx) {
 171       if (!glXIsDirect(gDpy, glCtx)) {
 172          printf("Warning: using indirect GLXContext\n");
 173       }
 174    }
 175    else {
 176       printf("Error: Couldn't create GLXContext\n");
 177       XCloseDisplay(gDpy);
 178       return 0;
 179    }
 180
 181    /* Bind context to pbuffer */
 182    if (!glXMakeCurrent(gDpy, gPBuffer, glCtx)) {
 183       printf("Error: glXMakeCurrent failed\n");
 184       XCloseDisplay(gDpy);
 185       return 0;
 186    }
 187
 188    return 1;  /* Success!! */
 189 #else
 190    printf("Error: GLX version 1.3 or 1.4 not available at compile time\n");
 191    return 0;
 192 #endif
 193 }
 194
 195
 196
 197 /* One-time GL setup */
 198 static void
 199 InitGL(void)
 200 {
 201    static GLfloat pos[4] = {0.0, 0.0, 10.0, 0.0};
 202    glEnable(GL_LIGHTING);
 203    glEnable(GL_LIGHT0);
 204    glLightfv(GL_LIGHT0, GL_POSITION, pos);
 205    glEnable(GL_NORMALIZE);
 206    glEnable(GL_DEPTH_TEST);
 207    glEnable(GL_CULL_FACE);
 208
 209    glViewport(0, 0, gWidth, gHeight);
 210    glMatrixMode( GL_PROJECTION );
 211    glLoadIdentity();
 212    glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
 213    glMatrixMode( GL_MODELVIEW );
 214    glLoadIdentity();
 215    glTranslatef( 0.0, 0.0, -15.0 );
 216
 217 }
 218
 219
 220 /* Return random float in [0,1] */
 221 static float
 222 Random(void)
 223 {
 224    int i = rand();
 225    return (float) (i % 1000) / 1000.0;
 226 }
 227
 228
 229 static void
 230 RandomColor(void)
 231 {
 232    GLfloat c[4];
 233    c[0] = Random();
 234    c[1] = Random();
 235    c[2] = Random();
 236    c[3] = 1.0;
 237    glMaterialfv(GL_FRONT, GL_AMBIENT_AND_DIFFUSE, c);
 238 }
 239
 240
 241 /* This function borrowed from Mark Kilgard's GLUT */
 242 static void
 243 drawBox(GLfloat x0, GLfloat x1, GLfloat y0, GLfloat y1,
 244         GLfloat z0, GLfloat z1, GLenum type)
 245 {
 246   static GLfloat n[6][3] =
 247   {
 248     {-1.0, 0.0, 0.0},
 249     {0.0, 1.0, 0.0},
 250     {1.0, 0.0, 0.0},
 251     {0.0, -1.0, 0.0},
 252     {0.0, 0.0, 1.0},
 253     {0.0, 0.0, -1.0}
 254   };
 255   static GLint faces[6][4] =
 256   {
 257     {0, 1, 2, 3},
 258     {3, 2, 6, 7},
 259     {7, 6, 5, 4},
 260     {4, 5, 1, 0},
 261     {5, 6, 2, 1},
 262     {7, 4, 0, 3}
 263   };
 264   GLfloat v[8][3], tmp;
 265   GLint i;
 266
 267   if (x0 > x1) {
 268     tmp = x0;
 269     x0 = x1;
 270     x1 = tmp;
 271   }
 272   if (y0 > y1) {
 273     tmp = y0;
 274     y0 = y1;
 275     y1 = tmp;
 276   }
 277   if (z0 > z1) {
 278     tmp = z0;
 279     z0 = z1;
 280     z1 = tmp;
 281   }
 282   v[0][0] = v[1][0] = v[2][0] = v[3][0] = x0;
 283   v[4][0] = v[5][0] = v[6][0] = v[7][0] = x1;
 284   v[0][1] = v[1][1] = v[4][1] = v[5][1] = y0;
 285   v[2][1] = v[3][1] = v[6][1] = v[7][1] = y1;
 286   v[0][2] = v[3][2] = v[4][2] = v[7][2] = z0;
 287   v[1][2] = v[2][2] = v[5][2] = v[6][2] = z1;
 288
 289   for (i = 0; i < 6; i++) {
 290     glBegin(type);
 291     glNormal3fv(&n[i][0]);
 292     glVertex3fv(&v[faces[i][0]][0]);
 293     glVertex3fv(&v[faces[i][1]][0]);
 294     glVertex3fv(&v[faces[i][2]][0]);
 295     glVertex3fv(&v[faces[i][3]][0]);
 296     glEnd();
 297   }
 298 }
 299
 300
 301
 302 /* Render a scene */
 303 static void
 304 Render(void)
 305 {
 306    int NumBoxes = 100;
 307    int i;
 308
 309    InitGL();
 310    glClearColor(0.2, 0.2, 0.9, 0.0);
 311    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 312
 313    for (i=0;i<NumBoxes;i++) {
 314       float tx = -2.0 + 4.0 * Random();
 315       float ty = -2.0 + 4.0 * Random();
 316       float tz =  4.0 - 16.0 * Random();
 317       float sx = 0.1 + Random() * 0.4;
 318       float sy = 0.1 + Random() * 0.4;
 319       float sz = 0.1 + Random() * 0.4;
 320       float rx = Random();
 321       float ry = Random();
 322       float rz = Random();
 323       float ra = Random() * 360.0;
 324       glPushMatrix();
 325       glTranslatef(tx, ty, tz);
 326       glRotatef(ra, rx, ry, rz);
 327       glScalef(sx, sy, sz);
 328       RandomColor();
 329       drawBox(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0, GL_POLYGON);
 330       glPopMatrix();
 331    }
 332
 333    glFinish();
 334 }
 335
 336
 337
 338 static void
 339 WriteFile(const char *filename)
 340 {
 341    FILE *f;
 342    GLubyte *image;
 343    int i;
 344
 345    image = malloc(gWidth * gHeight * 3 * sizeof(GLubyte));
 346    if (!image) {
 347       printf("Error: couldn't allocate image buffer\n");
 348       return;
 349    }
 350
 351    glPixelStorei(GL_PACK_ALIGNMENT, 1);
 352    glReadPixels(0, 0, gWidth, gHeight, GL_RGB, GL_UNSIGNED_BYTE, image);
 353
 354    f = fopen(filename, "w");
 355    if (!f) {
 356       printf("Couldn't open image file: %s\n", filename);
 357       return;
 358    }
 359    fprintf(f,"P6\n");
 360    fprintf(f,"# ppm-file created by %s\n", "trdemo2");
 361    fprintf(f,"%i %i\n", gWidth, gHeight);
 362    fprintf(f,"255\n");
 363    fclose(f);
 364    f = fopen(filename, "ab");  /* now append binary data */
 365    if (!f) {
 366       printf("Couldn't append to image file: %s\n", filename);
 367       return;
 368    }
 369
 370    for (i=0;i<gHeight;i++) {
 371       GLubyte *rowPtr;
 372       /* Remember, OpenGL images are bottom to top.  Have to reverse. */
 373       rowPtr = image + (gHeight-1-i) * gWidth*3;
 374       fwrite(rowPtr, 1, gWidth*3, f);
 375    }
 376
 377    fclose(f);
 378    free(image);
 379
 380    printf("Wrote %d by %d image file: %s\n", gWidth, gHeight, filename);
 381 }
 382
 383
 384
 385 /*
 386  * Print message describing command line parameters.
 387  */
 388 static void
 389 Usage(const char *appName)
 390 {
 391    printf("Usage:\n");
 392    printf("  %s width height imgfile\n", appName);
 393    printf("Where imgfile is a ppm file\n");
 394 }
 395
 396
 397
 398 int
 399 main(int argc, char *argv[])
 400 {
 401    if (argc!=4) {
 402       Usage(argv[0]);
 403    }
 404    else {
 405       int width = atoi(argv[1]);
 406       int height = atoi(argv[2]);
 407       char *fileName = argv[3];
 408       if (width<=0) {
 409          printf("Error: width parameter must be at least 1.\n");
 410          return 1;
 411       }
 412       if (height<=0) {
 413          printf("Error: height parameter must be at least 1.\n");
 414          return 1;
 415       }
 416       if (!Setup(width, height)) {
 417          return 1;
 418       }
 419
 420       printf("Setup completed\n");
 421       Render();
 422       printf("Render completed.\n");
 423       WriteFile(fileName);
 424       printf("File write completed.\n");
 425
 426       glXDestroyPbuffer( gDpy, gPBuffer );
 427    }
 428    return 0;
 429 }
 430