progs/demos/arbocclude2.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 #include <GL/glew.h>
  33 #include <GL/glut.h>
  34
  35 static GLboolean Anim = GL_TRUE;
  36 static GLfloat Xpos = 0;
  37 static GLuint OccQuery1;
  38 static GLuint OccQuery2;
  39 static GLint Win = 0;
  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 passed1, passed2;
  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 #if defined(GL_ARB_occlusion_query)
 112    glColorMask(0, 0, 0, 0);
 113    glDepthMask(GL_FALSE);
 114
 115    /* draw the first polygon with occlusion testing */
 116    glPushMatrix();
 117    glTranslatef(Xpos, 0.4, -0.5);
 118    glScalef(0.3, 0.3, 1.0);
 119    glRotatef(-90.0 * Xpos, 0, 0, 1);
 120
 121    glBeginQueryARB(GL_SAMPLES_PASSED_ARB, OccQuery1);
 122
 123    glBegin(GL_POLYGON);
 124    glVertex3f(-1, -1, 0);
 125    glVertex3f( 1, -1, 0);
 126    glVertex3f( 1,  1, 0);
 127    glVertex3f(-1,  1, 0);
 128    glEnd();
 129
 130    glEndQueryARB(GL_SAMPLES_PASSED_ARB);
 131
 132    /* draw the second polygon with occlusion testing */
 133    glPopMatrix();
 134    glPushMatrix();
 135    glTranslatef(Xpos, -0.4, -0.5);
 136    glScalef(0.3, 0.3, 1.0);
 137
 138    glBeginQueryARB(GL_SAMPLES_PASSED_ARB, OccQuery2);
 139
 140    glBegin(GL_POLYGON);
 141    glVertex3f(-1, -1, 0);
 142    glVertex3f( 1, -1, 0);
 143    glVertex3f( 1,  1, 0);
 144    glVertex3f(-1,  1, 0);
 145    glEnd();
 146
 147    glEndQueryARB(GL_SAMPLES_PASSED_ARB);
 148
 149    /* turn off occlusion testing */
 150    glColorMask(1, 1, 1, 1);
 151    glDepthMask(GL_TRUE);
 152
 153    do {
 154       /* do useful work here, if any */
 155       glGetQueryObjectivARB(OccQuery1, GL_QUERY_RESULT_AVAILABLE_ARB, &ready);
 156    } while (!ready);
 157    glGetQueryObjectuivARB(OccQuery1, GL_QUERY_RESULT_ARB, &passed1);
 158
 159    do {
 160       /* do useful work here, if any */
 161       glGetQueryObjectivARB(OccQuery2, GL_QUERY_RESULT_AVAILABLE_ARB, &ready);
 162    } while (!ready);
 163    glGetQueryObjectuivARB(OccQuery2, GL_QUERY_RESULT_ARB, &passed2);
 164 #endif /* GL_ARB_occlusion_query */
 165
 166    /* draw the second rect, so we can see what's going on */
 167    glColor3f(0.8, 0.5, 0);
 168    glBegin(GL_POLYGON);
 169    glVertex3f(-1, -1, 0);
 170    glVertex3f( 1, -1, 0);
 171    glVertex3f( 1,  1, 0);
 172    glVertex3f(-1,  1, 0);
 173    glEnd();
 174
 175    glPopMatrix();
 176    glPushMatrix();
 177    glTranslatef(Xpos, 0.4, -0.5);
 178    glScalef(0.3, 0.3, 1.0);
 179    glRotatef(-90.0 * Xpos, 0, 0, 1);
 180
 181    /* draw the first rect, so we can see what's going on */
 182    glBegin(GL_POLYGON);
 183    glVertex3f(-1, -1, 0);
 184    glVertex3f( 1, -1, 0);
 185    glVertex3f( 1,  1, 0);
 186    glVertex3f(-1,  1, 0);
 187    glEnd();
 188
 189    glPopMatrix();
 190
 191    /* Print result message */
 192    glMatrixMode( GL_PROJECTION );
 193    glLoadIdentity();
 194    glOrtho( -1.0, 1.0, -1.0, 1.0, -1.0, 1.0 );
 195    glMatrixMode( GL_MODELVIEW );
 196    glLoadIdentity();
 197
 198    glColor3f(1, 1, 1);
 199 #if defined(GL_ARB_occlusion_query)
 200    sprintf(s, " %4d Fragments Visible", passed1);
 201    glRasterPos3f(-0.50, -0.6, 0);
 202    PrintString(s);
 203    if (!passed1) {
 204       glRasterPos3f(-0.25, -0.7, 0);
 205       PrintString("Fully Occluded");
 206    }
 207    sprintf(s, " %4d Fragments Visible", passed2);
 208    glRasterPos3f(-0.50, -0.8, 0);
 209    PrintString(s);
 210    if (!passed2) {
 211       glRasterPos3f(-0.25, -0.9, 0);
 212       PrintString("Fully Occluded");
 213    }
 214 #else
 215    glRasterPos3f(-0.25, -0.8, 0);
 216    PrintString("GL_ARB_occlusion_query not available at compile time");
 217 #endif /* GL_ARB_occlusion_query */
 218
 219    glutSwapBuffers();
 220 }
 221
 222
 223 static void Reshape( int width, int height )
 224 {
 225    glViewport( 0, 0, width, height );
 226 }
 227
 228
 229 static void Key( unsigned char key, int x, int y )
 230 {
 231    (void) x;
 232    (void) y;
 233    switch (key) {
 234       case 27:
 235          glutDestroyWindow(Win);
 236          exit(0);
 237          break;
 238       case ' ':
 239          Anim = !Anim;
 240          if (Anim)
 241             glutIdleFunc(Idle);
 242          else
 243             glutIdleFunc(NULL);
 244          break;
 245    }
 246    glutPostRedisplay();
 247 }
 248
 249
 250 static void SpecialKey( int key, int x, int y )
 251 {
 252    const GLfloat step = 0.1;
 253    (void) x;
 254    (void) y;
 255    switch (key) {
 256       case GLUT_KEY_LEFT:
 257          Xpos -= step;
 258          break;
 259       case GLUT_KEY_RIGHT:
 260          Xpos += step;
 261          break;
 262    }
 263    glutPostRedisplay();
 264 }
 265
 266
 267 static void Init( void )
 268 {
 269    const char *ext = (const char *) glGetString(GL_EXTENSIONS);
 270    GLint bits;
 271
 272    if (!strstr(ext, "GL_ARB_occlusion_query")) {
 273       printf("Sorry, this demo requires the GL_ARB_occlusion_query extension\n");
 274       exit(-1);
 275    }
 276
 277 #if defined(GL_ARB_occlusion_query)
 278    glGetQueryivARB(GL_SAMPLES_PASSED_ARB, GL_QUERY_COUNTER_BITS_ARB, &bits);
 279    if (!bits) {
 280       printf("Hmmm, GL_QUERY_COUNTER_BITS_ARB is zero!\n");
 281       exit(-1);
 282    }
 283 #endif /* GL_ARB_occlusion_query */
 284
 285    glGetIntegerv(GL_DEPTH_BITS, &bits);
 286    printf("Depthbits: %d\n", bits);
 287
 288 #if defined(GL_ARB_occlusion_query)
 289    glGenQueriesARB(1, &OccQuery1);
 290    assert(OccQuery1 > 0);
 291    glGenQueriesARB(1, &OccQuery2);
 292    assert(OccQuery2 > 0);
 293 #endif /* GL_ARB_occlusion_query */
 294
 295    glEnable(GL_DEPTH_TEST);
 296 }
 297
 298
 299 int main( int argc, char *argv[] )
 300 {
 301    glutInitWindowSize( 400, 400 );
 302    glutInit( &argc, argv );
 303    glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH );
 304    Win = glutCreateWindow(argv[0]);
 305    glewInit();
 306    glutReshapeFunc( Reshape );
 307    glutKeyboardFunc( Key );
 308    glutSpecialFunc( SpecialKey );
 309    glutIdleFunc( Idle );
 310    glutDisplayFunc( Display );
 311    Init();
 312    glutMainLoop();
 313    return 0;
 314 }