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* GL_ARB_occlusion_query demo
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* Copyright (C) 2003 Brian Paul All Rights Reserved.
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
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* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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static GLboolean Anim = GL_TRUE;
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static GLfloat Xpos[NUM_OCC], Ypos[NUM_OCC];
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static GLfloat Sign[NUM_OCC];
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static GLuint OccQuery[NUM_OCC];
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PrintString(const char *s)
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glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s);
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static void Idle(void)
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static int lastTime = 0;
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int time = glutGet(GLUT_ELAPSED_TIME);
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else if (time - lastTime < 20) /* 50Hz update */
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for (i = 0; i < NUM_OCC; i++) {
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step = (time - lastTime) / 1000.0 * Sign[i];
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else if (Xpos[i] < -2.5) {
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static void Display( void )
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glClearColor(0.25, 0.25, 0.25, 0.0);
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glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
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glMatrixMode( GL_PROJECTION );
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glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 );
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glMatrixMode( GL_MODELVIEW );
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glTranslatef( 0.0, 0.0, -15.0 );
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/* draw the occluding polygons */
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glColor3f(0, 0.4, 0.6);
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glVertex2f(-1.6, -2.5);
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glVertex2f(-0.4, -2.5);
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glVertex2f(-0.4, 2.5);
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glVertex2f(-1.6, 2.5);
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glVertex2f( 0.4, -2.5);
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glVertex2f( 1.6, -2.5);
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glVertex2f( 1.6, 2.5);
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glVertex2f( 0.4, 2.5);
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glColorMask(0, 0, 0, 0);
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glDepthMask(GL_FALSE);
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/* draw the test polygons with occlusion testing */
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for (i = 0; i < NUM_OCC; i++) {
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glTranslatef(Xpos[i], Ypos[i], -0.5);
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glScalef(0.2, 0.2, 1.0);
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glRotatef(-90.0 * Xpos[i], 0, 0, 1);
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glBeginQueryARB(GL_SAMPLES_PASSED_ARB, OccQuery[i]);
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glVertex3f(-1, -1, 0);
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glVertex3f( 1, -1, 0);
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glVertex3f( 1, 1, 0);
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glVertex3f(-1, 1, 0);
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glEndQueryARB(GL_SAMPLES_PASSED_ARB);
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glColorMask(1, 1, 1, 1);
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glDepthMask(GL_TRUE);
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/* Draw the rectangles now.
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* Draw orange if result was ready
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* Draw red if result was not ready.
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for (i = 0; i < NUM_OCC; i++) {
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glGetQueryObjectivARB(OccQuery[i], GL_QUERY_RESULT_AVAILABLE_ARB, &ready);
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glGetQueryObjectuivARB(OccQuery[i], GL_QUERY_RESULT_ARB, &passed);
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glColor3f(0.8, 0.5, 0);
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if (!ready || passed) {
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glTranslatef(Xpos[i], Ypos[i], -0.5);
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glScalef(0.2, 0.2, 1.0);
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glRotatef(-90.0 * Xpos[i], 0, 0, 1);
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glVertex3f(-1, -1, 0);
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glVertex3f( 1, -1, 0);
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glVertex3f( 1, 1, 0);
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glVertex3f(-1, 1, 0);
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glRasterPos3f(0.45, Ypos[i], 1.0);
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sprintf(s, "%4d", passed);
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static void Reshape( int width, int height )
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glViewport( 0, 0, width, height );
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static void Key( unsigned char key, int x, int y )
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glutDestroyWindow(Win);
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static void SpecialKey( int key, int x, int y )
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const GLfloat step = 0.1;
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for (i = 0; i < NUM_OCC; i++)
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for (i = 0; i < NUM_OCC; i++)
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static void Init( void )
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const char *ext = (const char *) glGetString(GL_EXTENSIONS);
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if (!strstr(ext, "GL_ARB_occlusion_query")) {
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printf("Sorry, this demo requires the GL_ARB_occlusion_query extension\n");
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glGetQueryivARB(GL_SAMPLES_PASSED_ARB, GL_QUERY_COUNTER_BITS_ARB, &bits);
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printf("Hmmm, GL_QUERY_COUNTER_BITS_ARB is zero!\n");
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glGetIntegerv(GL_DEPTH_BITS, &bits);
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printf("Depthbits: %d\n", bits);
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glGenQueriesARB(NUM_OCC, OccQuery);
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glEnable(GL_DEPTH_TEST);
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for (i = 0; i < NUM_OCC; i++) {
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float t = (float) i / (NUM_OCC - 1);
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Ypos[i] = 4.0 * (t - 0.5);
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int main( int argc, char *argv[] )
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glutInitWindowSize( 400, 400 );
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glutInit( &argc, argv );
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glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH );
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Win = glutCreateWindow(argv[0]);
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glutReshapeFunc( Reshape );
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glutKeyboardFunc( Key );
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glutSpecialFunc( SpecialKey );
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glutDisplayFunc( Display );