progs/tests/fogcoord.c

   1 /*
   2  * Exercise GL_EXT_fog_coord
   3  */
   4
   5
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <math.h>
   9 #include <GL/glew.h>
  10 #include <GL/glut.h>
  11
  12 static int Width = 600;
  13 static int Height = 200;
  14 static GLfloat Near = 5.0, Far = 25.0;
  15
  16
  17 static void Display( void )
  18 {
  19    GLfloat t;
  20
  21    glClearColor(0.2, 0.2, 0.8, 0);
  22    glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT );
  23
  24    for (t = 0.0; t <= 1.0; t += 0.25) {
  25       GLfloat f = Near + t * (Far - Near);
  26       printf("glFogCoord(%4.1f)\n", f);
  27       glFogCoordfEXT(f);
  28
  29       glPushMatrix();
  30          glTranslatef(t * 10.0 - 5.0, 0, 0);
  31          glBegin(GL_POLYGON);
  32          glVertex2f(-1, -1);
  33          glVertex2f( 1, -1);
  34          glVertex2f( 1,  1);
  35          glVertex2f(-1,  1);
  36          glEnd();
  37       glPopMatrix();
  38    }
  39    glutSwapBuffers();
  40 }
  41
  42
  43 static void Reshape( int width, int height )
  44 {
  45    GLfloat ar = (float) width / (float) height;
  46    Width = width;
  47    Height = height;
  48    glViewport( 0, 0, width, height );
  49    glMatrixMode( GL_PROJECTION );
  50    glLoadIdentity();
  51    glFrustum( -ar, ar, -1.0, 1.0, Near, Far );
  52    glMatrixMode( GL_MODELVIEW );
  53    glLoadIdentity();
  54    glTranslatef( 0.0, 0.0, -15.0 );
  55 }
  56
  57
  58 static void Key( unsigned char key, int x, int y )
  59 {
  60    (void) x;
  61    (void) y;
  62    switch (key) {
  63       case 27:
  64          exit(0);
  65          break;
  66    }
  67    glutPostRedisplay();
  68 }
  69
  70
  71 static void Init( void )
  72 {
  73    printf("GL_RENDERER = %s\n", (char *) glGetString(GL_RENDERER));
  74    printf("GL_VERSION = %s\n", (char *) glGetString(GL_VERSION));
  75    /* setup lighting, etc */
  76    if (!glutExtensionSupported("GL_EXT_fog_coord")) {
  77       printf("Sorry, this program requires GL_EXT_fog_coord\n");
  78       exit(1);
  79    }
  80    glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FOG_COORDINATE_EXT);
  81    glFogi(GL_FOG_MODE, GL_LINEAR);
  82    glFogf(GL_FOG_START, Near);
  83    glFogf(GL_FOG_END, Far);
  84    glEnable(GL_FOG);
  85    printf("Squares should be colored from white -> gray -> black.\n");
  86 }
  87
  88
  89 int main( int argc, char *argv[] )
  90 {
  91    glutInit( &argc, argv );
  92    glutInitWindowPosition( 0, 0 );
  93    glutInitWindowSize( Width, Height );
  94    glutInitDisplayMode( GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH );
  95    glutCreateWindow(argv[0]);
  96    glewInit();
  97    glutReshapeFunc( Reshape );
  98    glutKeyboardFunc( Key );
  99    glutDisplayFunc( Display );
 100    Init();
 101    glutMainLoop();
 102    return 0;
 103 }