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 "glut_wrap.h"
34
35#define NUM_OCC 10
36
37static GLboolean Anim = GL_TRUE;
38static GLfloat Xpos[NUM_OCC], Ypos[NUM_OCC];
39static GLfloat Sign[NUM_OCC];
40static GLuint OccQuery[NUM_OCC];
41static GLint Win = 0;
42
43
44static void
45PrintString(const char *s)
46{
47   while (*s) {
48      glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
49      s++;
50   }
51}
52
53
54
55static 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
90static 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
188static void Reshape( int width, int height )
189{
190   glViewport( 0, 0, width, height );
191}
192
193
194static 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
215static 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
235static 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
269int 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   glewInit();
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}
288