progs/redbook/fogindex.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  34  * Unpublished-- rights reserved under the copyright laws of the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  *  fogindex.c
  42  *  This program demonstrates fog in color index mode.
  43  *  Three cones are drawn at different z values in a linear
  44  *  fog.  32 contiguous colors (from 16 to 47) are loaded
  45  *  with a color ramp.
  46  */
  47 #include <stdlib.h>
  48 #include <GL/glut.h>
  49
  50 /*  Initialize color map and fog.  Set screen clear color
  51  *  to end of color ramp.
  52  */
  53 #define NUM_COLORS 32
  54 #define RAMPSTART 16
  55
  56 static void
  57 myinit(void)
  58 {
  59   int i;
  60
  61   glEnable(GL_DEPTH_TEST);
  62   glDepthFunc(GL_LESS);
  63   for (i = 0; i < NUM_COLORS; i++) {
  64     GLfloat shade;
  65     shade = (GLfloat) (NUM_COLORS - i) / (GLfloat) NUM_COLORS;
  66     glutSetColor(16 + i, shade, shade, shade);
  67   }
  68   glEnable(GL_FOG);
  69
  70   glFogi(GL_FOG_MODE, GL_LINEAR);
  71   glFogi(GL_FOG_INDEX, NUM_COLORS);
  72   glFogf(GL_FOG_START, 0.0);
  73   glFogf(GL_FOG_END, 4.0);
  74   glHint(GL_FOG_HINT, GL_NICEST);
  75   glClearIndex((GLfloat) (NUM_COLORS + RAMPSTART - 1));
  76 }
  77
  78 /*  display() renders 3 cones at different z positions.
  79  */
  80 static void
  81 display(void)
  82 {
  83   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
  84   glPushMatrix();
  85   glTranslatef(-1.0, -1.0, -1.0);
  86   glRotatef(-90.0, 1.0, 0.0, 0.0);
  87   glIndexi(RAMPSTART);
  88   glutSolidCone(1.0, 2.0, 10, 10);
  89   glPopMatrix();
  90
  91   glPushMatrix();
  92   glTranslatef(0.0, -1.0, -2.25);
  93   glRotatef(-90.0, 1.0, 0.0, 0.0);
  94   glIndexi(RAMPSTART);
  95   glutSolidCone(1.0, 2.0, 10, 10);
  96   glPopMatrix();
  97
  98   glPushMatrix();
  99   glTranslatef(1.0, -1.0, -3.5);
 100   glRotatef(-90.0, 1.0, 0.0, 0.0);
 101   glIndexi(RAMPSTART);
 102   glutSolidCone(1.0, 2.0, 10, 10);
 103   glPopMatrix();
 104   glFlush();
 105 }
 106
 107 static void
 108 myReshape(int w, int h)
 109 {
 110   glViewport(0, 0, w, h);
 111   glMatrixMode(GL_PROJECTION);
 112   glLoadIdentity();
 113   if (w <= h)
 114     glOrtho(-2.0, 2.0, -2.0 * (GLfloat) h / (GLfloat) w,
 115       2.0 * (GLfloat) h / (GLfloat) w, 0.0, 10.0);
 116   else
 117     glOrtho(-2.0 * (GLfloat) w / (GLfloat) h,
 118       2.0 * (GLfloat) w / (GLfloat) h, -2.0, 2.0, 0.0, 10.0);
 119   glMatrixMode(GL_MODELVIEW);
 120   glLoadIdentity();
 121 }
 122
 123 static void
 124 key(unsigned char k, int x, int y)
 125 {
 126   switch (k) {
 127   case 27:  /* Escape */
 128     exit(0);
 129     break;
 130   default:
 131     return;
 132   }
 133   glutPostRedisplay();
 134 }
 135
 136 /*  Main Loop
 137  *  Open window with initial window size, title bar,
 138  *  RGBA display mode, depth buffer, and handle input events.
 139  */
 140 int
 141 main(int argc, char **argv)
 142 {
 143   glutInit(&argc, argv);
 144   glutInitDisplayMode(GLUT_SINGLE | GLUT_INDEX | GLUT_DEPTH);
 145   glutCreateWindow(argv[0]);
 146   myinit();
 147   glutReshapeFunc(myReshape);
 148   glutDisplayFunc(display);
 149   glutKeyboardFunc(key);
 150   glutMainLoop();
 151   return 0;             /* ANSI C requires main to return int. */
 152 }