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
  36 static GLboolean Anim = GL_TRUE;
  37 static GLfloat Xpos = 0;
  38 static GLuint OccQuery;
  39
  40
  41
  42 static void
  43 PrintString(const char *s)
  44 {
  45    while (*s) {
  46       glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
  47       s++;
  48    }
  49 }
  50
  51
  52
  53 static void Idle(void)
  54 {
  55    static int lastTime = 0;
  56    static int sign = +1;
  57    int time = glutGet(GLUT_ELAPSED_TIME);
  58    float step;
  59
  60    if (lastTime == 0)
  61       lastTime = time;
  62    else if (time - lastTime < 20)  /* 50Hz update */
  63       return;
  64
  65    step = (time - lastTime) / 1000.0 * sign;
  66    lastTime = time;
  67
  68    Xpos += step;
  69
  70    if (Xpos > 2.5) {
  71       Xpos = 2.5;
  72       sign = -1;
  73    }
  74    else if (Xpos < -2.5) {
  75       Xpos = -2.5;
  76       sign = +1;
  77    }
  78    glutPostRedisplay();
  79 }
  80
  81
  82 static void Display( void )
  83 {
  84    GLuint passed;
  85    GLint ready;
  86    char s[100];
  87
  88    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
  89
  90    glMatrixMode( GL_PROJECTION );
  91    glLoadIdentity();
  92    glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
  93    glMatrixMode( GL_MODELVIEW );
  94    glLoadIdentity();
  95    glTranslatef( 0.0, 0.0, -15.0 );
  96
  97    /* draw the occluding polygons */
  98    glColor3f(0, 0.6, 0.8);
  99    glBegin(GL_QUADS);
 100    glVertex2f(-1.6, -1.5);
 101    glVertex2f(-0.4, -1.5);
 102    glVertex2f(-0.4,  1.5);
 103    glVertex2f(-1.6,  1.5);
 104
 105    glVertex2f( 0.4, -1.5);
 106    glVertex2f( 1.6, -1.5);
 107    glVertex2f( 1.6,  1.5);
 108    glVertex2f( 0.4,  1.5);
 109    glEnd();
 110
 111    /* draw the test polygon with occlusion testing */
 112    glPushMatrix();
 113    glTranslatef(Xpos, 0, -0.5);
 114    glScalef(0.3, 0.3, 1.0);
 115    glRotatef(-90.0 * Xpos, 0, 0, 1);
 116
 117    glBeginQueryARB(GL_SAMPLES_PASSED_ARB, OccQuery);
 118
 119    glColorMask(0, 0, 0, 0);
 120    glDepthMask(GL_FALSE);
 121
 122    glBegin(GL_POLYGON);
 123    glVertex3f(-1, -1, 0);
 124    glVertex3f( 1, -1, 0);
 125    glVertex3f( 1,  1, 0);
 126    glVertex3f(-1,  1, 0);
 127    glEnd();
 128
 129    glEndQueryARB(GL_SAMPLES_PASSED_ARB);
 130
 131    do {
 132       /* do useful work here, if any */
 133       glGetQueryObjectivARB(OccQuery, GL_QUERY_RESULT_AVAILABLE_ARB, &ready);
 134    } while (!ready);
 135    glGetQueryObjectuivARB(OccQuery, GL_QUERY_RESULT_ARB, &passed);
 136
 137    /* turn off occlusion testing */
 138    glColorMask(1, 1, 1, 1);
 139    glDepthMask(GL_TRUE);
 140
 141    /* draw the orange rect, so we can see what's going on */
 142    glColor3f(0.8, 0.5, 0);
 143    glBegin(GL_POLYGON);
 144    glVertex3f(-1, -1, 0);
 145    glVertex3f( 1, -1, 0);
 146    glVertex3f( 1,  1, 0);
 147    glVertex3f(-1,  1, 0);
 148    glEnd();
 149
 150    glPopMatrix();
 151
 152
 153    /* Print result message */
 154    glMatrixMode( GL_PROJECTION );
 155    glLoadIdentity();
 156    glOrtho( -1.0, 1.0, -1.0, 1.0, -1.0, 1.0 );
 157    glMatrixMode( GL_MODELVIEW );
 158    glLoadIdentity();
 159
 160    glColor3f(1, 1, 1);
 161    sprintf(s, " %4d Fragments Visible", passed);
 162    glRasterPos3f(-0.50, -0.7, 0);
 163    PrintString(s);
 164    if (!passed) {
 165       glRasterPos3f(-0.25, -0.8, 0);
 166       PrintString("Fully Occluded");
 167    }
 168
 169    glutSwapBuffers();
 170 }
 171
 172
 173 static void Reshape( int width, int height )
 174 {
 175    glViewport( 0, 0, width, height );
 176 }
 177
 178
 179 static void Key( unsigned char key, int x, int y )
 180 {
 181    (void) x;
 182    (void) y;
 183    switch (key) {
 184       case 27:
 185          exit(0);
 186          break;
 187       case ' ':
 188          Anim = !Anim;
 189          if (Anim)
 190             glutIdleFunc(Idle);
 191          else
 192             glutIdleFunc(NULL);
 193          break;
 194    }
 195    glutPostRedisplay();
 196 }
 197
 198
 199 static void SpecialKey( int key, int x, int y )
 200 {
 201    const GLfloat step = 0.1;
 202    (void) x;
 203    (void) y;
 204    switch (key) {
 205       case GLUT_KEY_LEFT:
 206          Xpos -= step;
 207          break;
 208       case GLUT_KEY_RIGHT:
 209          Xpos += step;
 210          break;
 211    }
 212    glutPostRedisplay();
 213 }
 214
 215
 216 static void Init( void )
 217 {
 218    const char *ext = (const char *) glGetString(GL_EXTENSIONS);
 219    GLint bits;
 220
 221    if (!strstr(ext, "GL_ARB_occlusion_query")) {
 222       printf("Sorry, this demo requires the GL_ARB_occlusion_query extension\n");
 223       exit(-1);
 224    }
 225
 226    glGetQueryivARB(GL_SAMPLES_PASSED_ARB, GL_QUERY_COUNTER_BITS_ARB, &bits);
 227    if (!bits) {
 228       printf("Hmmm, GL_QUERY_COUNTER_BITS_ARB is zero!\n");
 229       exit(-1);
 230    }
 231
 232    glGenQueriesARB(1, &OccQuery);
 233    assert( glIsQueryARB(OccQuery) );
 234
 235    glEnable(GL_DEPTH_TEST);
 236 }
 237
 238
 239 int main( int argc, char *argv[] )
 240 {
 241    glutInit( &argc, argv );
 242    glutInitWindowPosition( 0, 0 );
 243    glutInitWindowSize( 400, 400 );
 244    glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH );
 245    glutCreateWindow(argv[0]);
 246    glutReshapeFunc( Reshape );
 247    glutKeyboardFunc( Key );
 248    glutSpecialFunc( SpecialKey );
 249    glutIdleFunc( Idle );
 250    glutDisplayFunc( Display );
 251    Init();
 252    glutMainLoop();
 253    return 0;
 254 }