progs/redbook/fog.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  34  * Unpublished-- rights reserved under the copyright laws of the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  *  fog.c
  42  *  This program draws 5 red teapots, each at a different
  43  *  z distance from the eye, in different types of fog.
  44  *  Pressing the left mouse button chooses between 3 types of
  45  *  fog:  exponential, exponential squared, and linear.
  46  *  In this program, there is a fixed density value, as well
  47  *  as fixed start and end values for the linear fog.
  48  */
  49 #include <stdlib.h>
  50 #include <math.h>
  51 #include <GL/glut.h>
  52
  53 GLint fogMode;
  54
  55 void
  56 selectFog(int mode)
  57 {
  58     switch(mode) {
  59     case GL_LINEAR:
  60         glFogf(GL_FOG_START, 1.0);
  61         glFogf(GL_FOG_END, 5.0);
  62         /* falls through */
  63     case GL_EXP2:
  64     case GL_EXP:
  65         glFogi(GL_FOG_MODE, mode);
  66         glutPostRedisplay();
  67         break;
  68     case 0:
  69         exit(0);
  70     }
  71 }
  72
  73 /*  Initialize z-buffer, projection matrix, light source,
  74  *  and lighting model.  Do not specify a material property here.
  75  */
  76 void
  77 myinit(void)
  78 {
  79     GLfloat position[] =
  80     {0.0, 3.0, 3.0, 0.0};
  81     GLfloat local_view[] =
  82     {0.0};
  83
  84     glEnable(GL_DEPTH_TEST);
  85     glDepthFunc(GL_LESS);
  86
  87     glLightfv(GL_LIGHT0, GL_POSITION, position);
  88     glLightModelfv(GL_LIGHT_MODEL_LOCAL_VIEWER, local_view);
  89
  90     glFrontFace(GL_CW);
  91     glEnable(GL_LIGHTING);
  92     glEnable(GL_LIGHT0);
  93     glEnable(GL_AUTO_NORMAL);
  94     glEnable(GL_NORMALIZE);
  95     glEnable(GL_FOG);
  96     {
  97         GLfloat fogColor[4] =
  98         {0.5, 0.5, 0.5, 1.0};
  99
 100         fogMode = GL_EXP;
 101         glFogi(GL_FOG_MODE, fogMode);
 102         glFogfv(GL_FOG_COLOR, fogColor);
 103         glFogf(GL_FOG_DENSITY, 0.35);
 104         glHint(GL_FOG_HINT, GL_DONT_CARE);
 105         glClearColor(0.5, 0.5, 0.5, 1.0);
 106     }
 107 }
 108
 109 void
 110 renderRedTeapot(GLfloat x, GLfloat y, GLfloat z)
 111 {
 112     float mat[4];
 113
 114     glPushMatrix();
 115     glTranslatef(x, y, z);
 116     mat[0] = 0.1745;
 117     mat[1] = 0.01175;
 118     mat[2] = 0.01175;
 119     mat[3] = 1.0;
 120     glMaterialfv(GL_FRONT, GL_AMBIENT, mat);
 121     mat[0] = 0.61424;
 122     mat[1] = 0.04136;
 123     mat[2] = 0.04136;
 124     glMaterialfv(GL_FRONT, GL_DIFFUSE, mat);
 125     mat[0] = 0.727811;
 126     mat[1] = 0.626959;
 127     mat[2] = 0.626959;
 128     glMaterialfv(GL_FRONT, GL_SPECULAR, mat);
 129     glMaterialf(GL_FRONT, GL_SHININESS, 0.6 * 128.0);
 130     glutSolidTeapot(1.0);
 131     glPopMatrix();
 132 }
 133
 134 /*  display() draws 5 teapots at different z positions.
 135  */
 136 void
 137 display(void)
 138 {
 139     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 140     renderRedTeapot(-4.0, -0.5, -1.0);
 141     renderRedTeapot(-2.0, -0.5, -2.0);
 142     renderRedTeapot(0.0, -0.5, -3.0);
 143     renderRedTeapot(2.0, -0.5, -4.0);
 144     renderRedTeapot(4.0, -0.5, -5.0);
 145     glFlush();
 146 }
 147
 148 void
 149 myReshape(int w, int h)
 150 {
 151     glViewport(0, 0, w, h);
 152     glMatrixMode(GL_PROJECTION);
 153     glLoadIdentity();
 154     if (w <= (h * 3))
 155         glOrtho(-6.0, 6.0, -2.0 * ((GLfloat) h * 3) / (GLfloat) w,
 156             2.0 * ((GLfloat) h * 3) / (GLfloat) w, 0.0, 10.0);
 157     else
 158         glOrtho(-6.0 * (GLfloat) w / ((GLfloat) h * 3),
 159             6.0 * (GLfloat) w / ((GLfloat) h * 3), -2.0, 2.0, 0.0, 10.0);
 160     glMatrixMode(GL_MODELVIEW);
 161     glLoadIdentity();
 162 }
 163
 164 static void
 165 key(unsigned char k, int x, int y)
 166 {
 167   switch (k) {
 168   case 27:  /* Escape */
 169     exit(0);
 170     break;
 171   default:
 172     return;
 173   }
 174   glutPostRedisplay();
 175 }
 176
 177 /*  Main Loop
 178  *  Open window with initial window size, title bar,
 179  *  RGBA display mode, depth buffer, and handle input events.
 180  */
 181 int
 182 main(int argc, char **argv)
 183 {
 184     glutInit(&argc, argv);
 185     glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
 186     glutInitWindowSize(450, 150);
 187     glutCreateWindow(argv[0]);
 188     myinit();
 189     glutReshapeFunc(myReshape);
 190     glutDisplayFunc(display);
 191     glutCreateMenu(selectFog);
 192     glutAddMenuEntry("Fog EXP", GL_EXP);
 193     glutAddMenuEntry("Fog EXP2", GL_EXP2);
 194     glutAddMenuEntry("Fog LINEAR", GL_LINEAR);
 195     glutAddMenuEntry("Quit", 0);
 196     glutAttachMenu(GLUT_RIGHT_BUTTON);
 197     glutKeyboardFunc(key);
 198     glutMainLoop();
 199     return 0;             /* ANSI C requires main to return int. */
 200 }