src/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 #include <glad/glad.h>
  33 #include "glut_wrap.h"
  34
  35 #define NUM_OCC 10
  36
  37 static GLboolean Anim = GL_TRUE;
  38 static GLfloat Xpos[NUM_OCC], Ypos[NUM_OCC];
  39 static GLfloat Sign[NUM_OCC];
  40 static GLuint OccQuery[NUM_OCC];
  41 static GLint Win = 0;
  42
  43
  44 static void
  45 PrintString(const char *s)
  46 {
  47    while (*s) {
  48       glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
  49       s++;
  50    }
  51 }
  52
  53
  54
  55 static void Idle(void)
  56 {
  57    static int lastTime = 0;
  58    int time = glutGet(GLUT_ELAPSED_TIME);
  59    float step;
  60    int i;
  61
  62    if (lastTime == 0)
  63       lastTime = time;
  64    else if (time - lastTime < 20)  /* 50Hz update */
  65       return;
  66
  67    for (i = 0; i < NUM_OCC; i++) {
  68
  69       step = (time - lastTime) / 1000.0 * Sign[i];
  70
  71       Xpos[i] += step;
  72
  73       if (Xpos[i] > 2.5) {
  74          Xpos[i] = 2.5;
  75          Sign[i] = -1;
  76       }
  77       else if (Xpos[i] < -2.5) {
  78          Xpos[i] = -2.5;
  79          Sign[i] = +1;
  80       }
  81
  82    }
  83
  84    lastTime = time;
  85
  86    glutPostRedisplay();
  87 }
  88
  89
  90 static void Display( void )
  91 {
  92    int i;
  93
  94    glClearColor(0.25, 0.25, 0.25, 0.0);
  95    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
  96
  97    glMatrixMode( GL_PROJECTION );
  98    glLoadIdentity();
  99    glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
 100    glMatrixMode( GL_MODELVIEW );
 101    glLoadIdentity();
 102    glTranslatef( 0.0, 0.0, -15.0 );
 103
 104    /* draw the occluding polygons */
 105    glColor3f(0, 0.4, 0.6);
 106    glBegin(GL_QUADS);
 107    glVertex2f(-1.6, -2.5);
 108    glVertex2f(-0.4, -2.5);
 109    glVertex2f(-0.4,  2.5);
 110    glVertex2f(-1.6,  2.5);
 111    glVertex2f( 0.4, -2.5);
 112    glVertex2f( 1.6, -2.5);
 113    glVertex2f( 1.6,  2.5);
 114    glVertex2f( 0.4,  2.5);
 115    glEnd();
 116
 117
 118    glColorMask(0, 0, 0, 0);
 119    glDepthMask(GL_FALSE);
 120
 121    /* draw the test polygons with occlusion testing */
 122    for (i = 0; i < NUM_OCC; i++) {
 123       glPushMatrix();
 124          glTranslatef(Xpos[i], Ypos[i], -0.5);
 125          glScalef(0.2, 0.2, 1.0);
 126          glRotatef(-90.0 * Xpos[i], 0, 0, 1);
 127
 128          glBeginQueryARB(GL_SAMPLES_PASSED_ARB, OccQuery[i]);
 129          glBegin(GL_POLYGON);
 130          glVertex3f(-1, -1, 0);
 131          glVertex3f( 1, -1, 0);
 132          glVertex3f( 1,  1, 0);
 133          glVertex3f(-1,  1, 0);
 134          glEnd();
 135          glEndQueryARB(GL_SAMPLES_PASSED_ARB);
 136
 137       glPopMatrix();
 138    }
 139
 140    glColorMask(1, 1, 1, 1);
 141    glDepthMask(GL_TRUE);
 142
 143    /* Draw the rectangles now.
 144     * Draw orange if result was ready
 145     * Draw red if result was not ready.
 146     */
 147    for (i = 0; i < NUM_OCC; i++) {
 148       GLuint passed;
 149       GLint ready;
 150
 151       glGetQueryObjectivARB(OccQuery[i], GL_QUERY_RESULT_AVAILABLE_ARB, &ready);
 152
 153       glGetQueryObjectuivARB(OccQuery[i], GL_QUERY_RESULT_ARB, &passed);
 154
 155       if (!ready)
 156          glColor3f(1, 0, 0);
 157       else
 158          glColor3f(0.8, 0.5, 0);
 159
 160       if (!ready || passed) {
 161          glPushMatrix();
 162             glTranslatef(Xpos[i], Ypos[i], -0.5);
 163             glScalef(0.2, 0.2, 1.0);
 164             glRotatef(-90.0 * Xpos[i], 0, 0, 1);
 165
 166             glBegin(GL_POLYGON);
 167             glVertex3f(-1, -1, 0);
 168             glVertex3f( 1, -1, 0);
 169             glVertex3f( 1,  1, 0);
 170             glVertex3f(-1,  1, 0);
 171             glEnd();
 172
 173          glPopMatrix();
 174       }
 175
 176       {
 177          char s[10];
 178          glRasterPos3f(0.45, Ypos[i], 1.0);
 179          sprintf(s, "%4d", passed);
 180          PrintString(s);
 181       }
 182    }
 183
 184    glutSwapBuffers();
 185 }
 186
 187
 188 static void Reshape( int width, int height )
 189 {
 190    glViewport( 0, 0, width, height );
 191 }
 192
 193
 194 static void Key( unsigned char key, int x, int y )
 195 {
 196    (void) x;
 197    (void) y;
 198    switch (key) {
 199       case 27:
 200          glutDestroyWindow(Win);
 201          exit(0);
 202          break;
 203       case ' ':
 204          Anim = !Anim;
 205          if (Anim)
 206             glutIdleFunc(Idle);
 207          else
 208             glutIdleFunc(NULL);
 209          break;
 210    }
 211    glutPostRedisplay();
 212 }
 213
 214
 215 static void SpecialKey( int key, int x, int y )
 216 {
 217    const GLfloat step = 0.1;
 218    int i;
 219    (void) x;
 220    (void) y;
 221    switch (key) {
 222       case GLUT_KEY_LEFT:
 223          for (i = 0; i < NUM_OCC; i++)
 224             Xpos[i] -= step;
 225          break;
 226       case GLUT_KEY_RIGHT:
 227          for (i = 0; i < NUM_OCC; i++)
 228             Xpos[i] += step;
 229          break;
 230    }
 231    glutPostRedisplay();
 232 }
 233
 234
 235 static void Init( void )
 236 {
 237    const char *ext = (const char *) glGetString(GL_EXTENSIONS);
 238    GLint bits;
 239    int i;
 240
 241    if (!strstr(ext, "GL_ARB_occlusion_query")) {
 242       printf("Sorry, this demo requires the GL_ARB_occlusion_query extension\n");
 243       exit(-1);
 244    }
 245
 246    glGetQueryivARB(GL_SAMPLES_PASSED_ARB, GL_QUERY_COUNTER_BITS_ARB, &bits);
 247    if (!bits) {
 248       printf("Hmmm, GL_QUERY_COUNTER_BITS_ARB is zero!\n");
 249       exit(-1);
 250    }
 251
 252    glGetIntegerv(GL_DEPTH_BITS, &bits);
 253    printf("Depthbits: %d\n", bits);
 254
 255    glGenQueriesARB(NUM_OCC, OccQuery);
 256
 257    glEnable(GL_DEPTH_TEST);
 258
 259    for (i = 0; i < NUM_OCC; i++) {
 260       float t = (float) i / (NUM_OCC - 1);
 261       Xpos[i] = 2.5 * t;
 262       Ypos[i] = 4.0 * (t - 0.5);
 263       Sign[i] = 1.0;
 264    }
 265
 266 }
 267
 268
 269 int main( int argc, char *argv[] )
 270 {
 271    glutInitWindowSize( 400, 400 );
 272    glutInit( &argc, argv );
 273    glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH );
 274    Win = glutCreateWindow(argv[0]);
 275    gladLoadGL();
 276    glutReshapeFunc( Reshape );
 277    glutKeyboardFunc( Key );
 278    glutSpecialFunc( SpecialKey );
 279    if (Anim)
 280       glutIdleFunc(Idle);
 281    else
 282       glutIdleFunc(NULL);
 283    glutDisplayFunc( Display );
 284    Init();
 285    glutMainLoop();
 286    return 0;
 287 }