103 lines
2.2 KiB
C
103 lines
2.2 KiB
C
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/*
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* Exercise GL_EXT_fog_coord
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*/
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#define GL_GLEXT_PROTOTYPES
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <GL/glut.h>
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static int Width = 600;
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static int Height = 200;
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static GLfloat Near = 5.0, Far = 25.0;
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static void Display( void )
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{
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GLfloat t;
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glClearColor(0.2, 0.2, 0.8, 0);
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glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
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for (t = 0.0; t <= 1.0; t += 0.25) {
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GLfloat f = Near + t * (Far - Near);
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printf("glFogCoord(%4.1f)\n", f);
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glFogCoordfEXT(f);
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glPushMatrix();
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glTranslatef(t * 10.0 - 5.0, 0, 0);
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glBegin(GL_POLYGON);
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glVertex2f(-1, -1);
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glVertex2f( 1, -1);
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glVertex2f( 1, 1);
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glVertex2f(-1, 1);
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glEnd();
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glPopMatrix();
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}
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glutSwapBuffers();
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}
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static void Reshape( int width, int height )
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{
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GLfloat ar = (float) width / (float) height;
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Width = width;
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Height = height;
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glViewport( 0, 0, width, height );
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glMatrixMode( GL_PROJECTION );
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glLoadIdentity();
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glFrustum( -ar, ar, -1.0, 1.0, Near, Far );
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glMatrixMode( GL_MODELVIEW );
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glLoadIdentity();
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glTranslatef( 0.0, 0.0, -15.0 );
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}
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static void Key( unsigned char key, int x, int y )
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{
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(void) x;
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(void) y;
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switch (key) {
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case 27:
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exit(0);
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break;
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}
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glutPostRedisplay();
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}
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static void Init( void )
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{
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printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
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printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
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/* setup lighting, etc */
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if (!glutExtensionSupported("GL_EXT_fog_coord")) {
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printf("Sorry, this program requires GL_EXT_fog_coord\n");
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exit(1);
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}
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glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FOG_COORDINATE_EXT);
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glFogi(GL_FOG_MODE, GL_LINEAR);
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glFogf(GL_FOG_START, Near);
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glFogf(GL_FOG_END, Far);
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glEnable(GL_FOG);
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printf("Squares should be colored from white -> gray -> black.\n");
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}
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int main( int argc, char *argv[] )
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{
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glutInit( &argc, argv );
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glutInitWindowPosition( 0, 0 );
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glutInitWindowSize( Width, Height );
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glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH );
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glutCreateWindow(argv[0]);
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glutReshapeFunc( Reshape );
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glutKeyboardFunc( Key );
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glutDisplayFunc( Display );
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Init();
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glutMainLoop();
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return 0;
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}
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