src/redbook/depthcue.c

   1
   2 /* Copyright (c) Mark J. Kilgard, 1994. */
   3
   4 /*
   5  * (c) Copyright 1993, Silicon Graphics, Inc.
   6  * ALL RIGHTS RESERVED
   7  * Permission to use, copy, modify, and distribute this software for
   8  * any purpose and without fee is hereby granted, provided that the above
   9  * copyright notice appear in all copies and that both the copyright notice
  10  * and this permission notice appear in supporting documentation, and that
  11  * the name of Silicon Graphics, Inc. not be used in advertising
  12  * or publicity pertaining to distribution of the software without specific,
  13  * written prior permission.
  14  *
  15  * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
  16  * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
  18  * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
  19  * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
  20  * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
  21  * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
  22  * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
  23  * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
  24  * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
  25  * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
  26  * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
  27  *
  28  * US Government Users Restricted Rights
  29  * Use, duplication, or disclosure by the Government is subject to
  30  * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
  31  * (c)(1)(ii) of the Rights in Technical Data and Computer Software
  32  * clause at DFARS 252.227-7013 and/or in similar or successor
  33  * clauses in the FAR or the DOD or NASA FAR Supplement.
  34  * Unpublished-- rights reserved under the copyright laws of the
  35  * United States.  Contractor/manufacturer is Silicon Graphics,
  36  * Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
  37  *
  38  * OpenGL(TM) is a trademark of Silicon Graphics, Inc.
  39  */
  40 /*
  41  *  depthcue.c
  42  *  This program draws a wireframe model, which uses
  43  *  intensity (brightness) to give clues to distance.
  44  *  Fog is used to achieve this effect.
  45  */
  46 #include <stdlib.h>
  47 #include <GL/glut.h>
  48
  49 /*  Initialize linear fog for depth cueing.
  50  */
  51 void myinit(void)
  52 {
  53     GLfloat fogColor[4] = {0.0, 0.0, 0.0, 1.0};
  54
  55     glEnable(GL_FOG);
  56     glFogi (GL_FOG_MODE, GL_LINEAR);
  57     glHint (GL_FOG_HINT, GL_NICEST);  /*  per pixel   */
  58     glFogf (GL_FOG_START, 3.0);
  59     glFogf (GL_FOG_END, 5.0);
  60     glFogfv (GL_FOG_COLOR, fogColor);
  61     glClearColor(0.0, 0.0, 0.0, 1.0);
  62
  63     glDepthFunc(GL_LESS);
  64     glEnable(GL_DEPTH_TEST);
  65     glShadeModel(GL_FLAT);
  66 }
  67
  68 /*  display() draws an icosahedron.
  69  */
  70 void display(void)
  71 {
  72     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  73     glColor3f (1.0, 1.0, 1.0);
  74     glutWireIcosahedron();
  75     glFlush();
  76 }
  77
  78 void myReshape(int w, int h)
  79 {
  80     glViewport(0, 0, w, h);
  81     glMatrixMode(GL_PROJECTION);
  82     glLoadIdentity();
  83     gluPerspective (45.0, (GLfloat) w/(GLfloat) h, 3.0, 5.0);
  84     glMatrixMode(GL_MODELVIEW);
  85     glLoadIdentity ();
  86     glTranslatef (0.0, 0.0, -4.0);  /*  move object into view   */
  87 }
  88
  89 static void
  90 key(unsigned char k, int x, int y)
  91 {
  92   switch (k) {
  93   case 27:  /* Escape */
  94     exit(0);
  95     break;
  96   default:
  97     return;
  98   }
  99   glutPostRedisplay();
 100 }
 101
 102 /*  Main Loop
 103  */
 104 int main(int argc, char** argv)
 105 {
 106     glutInit(&argc, argv);
 107     glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
 108     glutCreateWindow(argv[0]);
 109     myinit();
 110     glutReshapeFunc(myReshape);
 111     glutDisplayFunc(display);
 112     glutKeyboardFunc(key);
 113     glutMainLoop();
 114     return 0;             /* ANSI C requires main to return int. */
 115 }