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| -rw-r--r-- | progs/demos/occlude.c | 226 |
1 files changed, 226 insertions, 0 deletions
diff --git a/progs/demos/occlude.c b/progs/demos/occlude.c new file mode 100644 index 00000000000..f807fffc76b --- /dev/null +++ b/progs/demos/occlude.c @@ -0,0 +1,226 @@ +/* + * 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 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 */ + 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 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; +} |