/* * GL_HP_occlustion_test demo * * Brian Paul * 31 March 2000 * * Copyright (C) 2000 Brian Paul All Rights Reserved. * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included * in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ #include <stdio.h> #include <stdlib.h> #include <string.h> #include <math.h> #include <GL/glut.h> #include <GL/glext.h> static GLfloat Xpos = 0; static GLboolean Anim = GL_TRUE; static void PrintString(const char *s) { while (*s) { glutBitmapCharacter(GLUT_BITMAP_8_BY_13, (int) *s); s++; } } static void Idle(void) { static int lastTime = 0; static int sign = +1; int time = glutGet(GLUT_ELAPSED_TIME); float step; if (lastTime == 0) lastTime = time; else if (time - lastTime < 20) /* 50Hz update */ return; step = (time - lastTime) / 1000.0 * sign; lastTime = time; Xpos += step; if (Xpos > 2.5) { Xpos = 2.5; sign = -1; } else if (Xpos < -2.5) { Xpos = -2.5; sign = +1; } glutPostRedisplay(); } static void Display( void ) { GLboolean result; glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); glMatrixMode( GL_PROJECTION ); glLoadIdentity(); glFrustum( -1.0, 1.0, -1.0, 1.0, 5.0, 25.0 ); glMatrixMode( GL_MODELVIEW ); glLoadIdentity(); glTranslatef( 0.0, 0.0, -15.0 ); /* draw the occluding polygons */ glColor3f(0, 0.6, 0.8); glBegin(GL_QUADS); glVertex2f(-1.6, -1.5); glVertex2f(-0.4, -1.5); glVertex2f(-0.4, 1.5); glVertex2f(-1.6, 1.5); glVertex2f( 0.4, -1.5); glVertex2f( 1.6, -1.5); glVertex2f( 1.6, 1.5); glVertex2f( 0.4, 1.5); glEnd(); /* draw the test polygon with occlusion testing */ glPushMatrix(); glTranslatef(Xpos, 0, -0.5); glScalef(0.3, 0.3, 1.0); glRotatef(-90.0 * Xpos, 0, 0, 1); glEnable(GL_OCCLUSION_TEST_HP); /* NOTE: enabling the occlusion test */ /* doesn't clear the result flag! */ glColorMask(0, 0, 0, 0); glDepthMask(GL_FALSE); /* this call clear's the result flag. Not really needed for this demo. */ glGetBooleanv(GL_OCCLUSION_TEST_RESULT_HP, &result); glBegin(GL_POLYGON); glVertex3f(-1, -1, 0); glVertex3f( 1, -1, 0); glVertex3f( 1, 1, 0); glVertex3f(-1, 1, 0); glEnd(); glGetBooleanv(GL_OCCLUSION_TEST_RESULT_HP, &result); /* turn off occlusion testing */ glDisable(GL_OCCLUSION_TEST_HP); glColorMask(1, 1, 1, 1); glDepthMask(GL_TRUE); /* draw the green rect, so we can see what's going on */ glColor3f(0.8, 0.5, 0); glBegin(GL_POLYGON); glVertex3f(-1, -1, 0); glVertex3f( 1, -1, 0); glVertex3f( 1, 1, 0); glVertex3f(-1, 1, 0); glEnd(); glPopMatrix(); /* Print result message */ glMatrixMode( GL_PROJECTION ); glLoadIdentity(); glOrtho( -1.0, 1.0, -1.0, 1.0, -1.0, 1.0 ); glMatrixMode( GL_MODELVIEW ); glLoadIdentity(); glColor3f(1, 1, 1); glRasterPos3f(-0.25, -0.7, 0); if (result) PrintString(" Visible"); else PrintString("Fully Occluded"); glutSwapBuffers(); } static void Reshape( int width, int height ) { glViewport( 0, 0, width, height ); } static void Key( unsigned char key, int x, int y ) { (void) x; (void) y; switch (key) { case 'a': Anim = !Anim; if (Anim) glutIdleFunc( Idle ); else glutIdleFunc( NULL ); break; case 27: exit(0); break; } glutPostRedisplay(); } static void SpecialKey( int key, int x, int y ) { const GLfloat step = 0.1; (void) x; (void) y; switch (key) { case GLUT_KEY_LEFT: Xpos -= step; break; case GLUT_KEY_RIGHT: Xpos += step; break; } glutPostRedisplay(); } static void Init( void ) { const char *ext = (const char *) glGetString(GL_EXTENSIONS); if (!strstr(ext, "GL_HP_occlusion_test")) { printf("Sorry, this demo requires the GL_HP_occlusion_test extension\n"); exit(-1); } glEnable(GL_DEPTH_TEST); } int main( int argc, char *argv[] ) { glutInit( &argc, argv ); glutInitWindowPosition( 0, 0 ); glutInitWindowSize( 400, 400 ); glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH ); glutCreateWindow(argv[0]); glutReshapeFunc( Reshape ); glutKeyboardFunc( Key ); glutSpecialFunc( SpecialKey ); glutIdleFunc( Idle ); glutDisplayFunc( Display ); Init(); glutMainLoop(); return 0; }