progs/demos/arbocclude.c

   1 /*
   2  * GL_ARB_occlusion_query demo
   3  *
   4  * Brian Paul
   5  * 12 June 2003
   6  *
   7  * Copyright (C) 2003  Brian Paul   All Rights Reserved.
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining a
  10  * copy of this software and associated documentation files (the "Software"),
  11  * to deal in the Software without restriction, including without limitation
  12  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  13  * and/or sell copies of the Software, and to permit persons to whom the
  14  * Software is furnished to do so, subject to the following conditions:
  15  *
  16  * The above copyright notice and this permission notice shall be included
  17  * in all copies or substantial portions of the Software.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  20  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  22  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
  23  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  24  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  */
  26
  27 #include <assert.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <math.h>
  32 #define GL_GLEXT_PROTOTYPES
  33 #include <GL/glut.h>
  34
  35 #define TEST_DISPLAY_LISTS 0
  36
  37 static GLboolean Anim = GL_TRUE;
  38 static GLfloat Xpos = 0;
  39 static GLuint OccQuery;
  40 static GLint Win = 0;
  41
  42
  43 static void
  44 PrintString(const char *s)
  45 {
  46    while (*s) {
  47       glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
  48       s++;
  49    }
  50 }
  51
  52
  53
  54 static void Idle(void)
  55 {
  56    static int lastTime = 0;
  57    static int sign = +1;
  58    int time = glutGet(GLUT_ELAPSED_TIME);
  59    float step;
  60
  61    if (lastTime == 0)
  62       lastTime = time;
  63    else if (time - lastTime < 20)  /* 50Hz update */
  64       return;
  65
  66    step = (time - lastTime) / 1000.0 * sign;
  67    lastTime = time;
  68
  69    Xpos += step;
  70
  71    if (Xpos > 2.5) {
  72       Xpos = 2.5;
  73       sign = -1;
  74    }
  75    else if (Xpos < -2.5) {
  76       Xpos = -2.5;
  77       sign = +1;
  78    }
  79    glutPostRedisplay();
  80 }
  81
  82
  83 static void Display( void )
  84 {
  85    GLuint passed;
  86    GLint ready;
  87    char s[100];
  88
  89    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
  90
  91    glMatrixMode( GL_PROJECTION );
  92    glLoadIdentity();
  93    glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
  94    glMatrixMode( GL_MODELVIEW );
  95    glLoadIdentity();
  96    glTranslatef( 0.0, 0.0, -15.0 );
  97
  98    /* draw the occluding polygons */
  99    glColor3f(0, 0.6, 0.8);
 100    glBegin(GL_QUADS);
 101    glVertex2f(-1.6, -1.5);
 102    glVertex2f(-0.4, -1.5);
 103    glVertex2f(-0.4,  1.5);
 104    glVertex2f(-1.6,  1.5);
 105
 106    glVertex2f( 0.4, -1.5);
 107    glVertex2f( 1.6, -1.5);
 108    glVertex2f( 1.6,  1.5);
 109    glVertex2f( 0.4,  1.5);
 110    glEnd();
 111
 112    /* draw the test polygon with occlusion testing */
 113    glPushMatrix();
 114    glTranslatef(Xpos, 0, -0.5);
 115    glScalef(0.3, 0.3, 1.0);
 116    glRotatef(-90.0 * Xpos, 0, 0, 1);
 117
 118 #if defined(GL_ARB_occlusion_query)
 119 #if TEST_DISPLAY_LISTS
 120    glNewList(10, GL_COMPILE);
 121    glBeginQueryARB(GL_SAMPLES_PASSED_ARB, OccQuery);
 122    glEndList();
 123    glCallList(10);
 124 #else
 125    glBeginQueryARB(GL_SAMPLES_PASSED_ARB, OccQuery);
 126 #endif
 127
 128    glColorMask(0, 0, 0, 0);
 129    glDepthMask(GL_FALSE);
 130
 131    glBegin(GL_POLYGON);
 132    glVertex3f(-1, -1, 0);
 133    glVertex3f( 1, -1, 0);
 134    glVertex3f( 1,  1, 0);
 135    glVertex3f(-1,  1, 0);
 136    glEnd();
 137
 138 #if TEST_DISPLAY_LISTS
 139    glNewList(11, GL_COMPILE);
 140    glEndQueryARB(GL_SAMPLES_PASSED_ARB);
 141    glEndList();
 142    glCallList(11);
 143 #else
 144    glEndQueryARB(GL_SAMPLES_PASSED_ARB);
 145 #endif
 146
 147    do {
 148       /* do useful work here, if any */
 149       glGetQueryObjectivARB(OccQuery, GL_QUERY_RESULT_AVAILABLE_ARB, &ready);
 150    } while (!ready);
 151    glGetQueryObjectuivARB(OccQuery, GL_QUERY_RESULT_ARB, &passed);
 152
 153    /* turn off occlusion testing */
 154    glColorMask(1, 1, 1, 1);
 155    glDepthMask(GL_TRUE);
 156 #endif /* GL_ARB_occlusion_query */
 157
 158    /* draw the orange rect, so we can see what's going on */
 159    glColor3f(0.8, 0.5, 0);
 160    glBegin(GL_POLYGON);
 161    glVertex3f(-1, -1, 0);
 162    glVertex3f( 1, -1, 0);
 163    glVertex3f( 1,  1, 0);
 164    glVertex3f(-1,  1, 0);
 165    glEnd();
 166
 167    glPopMatrix();
 168
 169
 170    /* Print result message */
 171    glMatrixMode( GL_PROJECTION );
 172    glLoadIdentity();
 173    glOrtho( -1.0, 1.0, -1.0, 1.0, -1.0, 1.0 );
 174    glMatrixMode( GL_MODELVIEW );
 175    glLoadIdentity();
 176
 177    glColor3f(1, 1, 1);
 178 #if defined(GL_ARB_occlusion_query)
 179    sprintf(s, " %4d Fragments Visible", passed);
 180    glRasterPos3f(-0.50, -0.7, 0);
 181    PrintString(s);
 182    if (!passed) {
 183       glRasterPos3f(-0.25, -0.8, 0);
 184       PrintString("Fully Occluded");
 185    }
 186 #else
 187    glRasterPos3f(-0.25, -0.8, 0);
 188    PrintString("GL_ARB_occlusion_query not available at compile time");
 189 #endif /* GL_ARB_occlusion_query */
 190
 191    glutSwapBuffers();
 192 }
 193
 194
 195 static void Reshape( int width, int height )
 196 {
 197    glViewport( 0, 0, width, height );
 198 }
 199
 200
 201 static void Key( unsigned char key, int x, int y )
 202 {
 203    (void) x;
 204    (void) y;
 205    switch (key) {
 206       case 27:
 207          glutDestroyWindow(Win);
 208          exit(0);
 209          break;
 210       case ' ':
 211          Anim = !Anim;
 212          if (Anim)
 213             glutIdleFunc(Idle);
 214          else
 215             glutIdleFunc(NULL);
 216          break;
 217    }
 218    glutPostRedisplay();
 219 }
 220
 221
 222 static void SpecialKey( int key, int x, int y )
 223 {
 224    const GLfloat step = 0.1;
 225    (void) x;
 226    (void) y;
 227    switch (key) {
 228       case GLUT_KEY_LEFT:
 229          Xpos -= step;
 230          break;
 231       case GLUT_KEY_RIGHT:
 232          Xpos += step;
 233          break;
 234    }
 235    glutPostRedisplay();
 236 }
 237
 238
 239 static void Init( void )
 240 {
 241    const char *ext = (const char *) glGetString(GL_EXTENSIONS);
 242    GLint bits;
 243
 244    if (!strstr(ext, "GL_ARB_occlusion_query")) {
 245       printf("Sorry, this demo requires the GL_ARB_occlusion_query extension\n");
 246       exit(-1);
 247    }
 248
 249 #if defined(GL_ARB_occlusion_query)
 250    glGetQueryivARB(GL_SAMPLES_PASSED_ARB, GL_QUERY_COUNTER_BITS_ARB, &bits);
 251    if (!bits) {
 252       printf("Hmmm, GL_QUERY_COUNTER_BITS_ARB is zero!\n");
 253       exit(-1);
 254    }
 255 #endif /* GL_ARB_occlusion_query */
 256
 257    glGetIntegerv(GL_DEPTH_BITS, &bits);
 258    printf("Depthbits: %d\n", bits);
 259
 260 #if defined(GL_ARB_occlusion_query)
 261    glGenQueriesARB(1, &OccQuery);
 262    assert(OccQuery > 0);
 263 #endif /* GL_ARB_occlusion_query */
 264
 265    glEnable(GL_DEPTH_TEST);
 266 }
 267
 268
 269 int main( int argc, char *argv[] )
 270 {
 271    glutInit( &argc, argv );
 272    glutInitWindowPosition( 0, 0 );
 273    glutInitWindowSize( 400, 400 );
 274    glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH );
 275    Win = glutCreateWindow(argv[0]);
 276    glutReshapeFunc( Reshape );
 277    glutKeyboardFunc( Key );
 278    glutSpecialFunc( SpecialKey );
 279    glutIdleFunc( Idle );
 280    glutDisplayFunc( Display );
 281    Init();
 282    glutMainLoop();
 283    return 0;
 284 }