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  34  * Unpublished-- rights reserved under the copyright laws of the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         mode = 0xfff;
  64     case GL_EXP2:
  65     case GL_EXP:
  66        glFogiv(0xf/*GL_FOG_MODE*/, (int *) &mode);
  67         glutPostRedisplay();
  68         break;
  69     case 0:
  70         exit(0);
  71     }
  72 }
  73
  74 /*  Initialize z-buffer, projection matrix, light source,
  75  *  and lighting model.  Do not specify a material property here.
  76  */
  77 void
  78 myinit(void)
  79 {
  80     GLfloat position[] =
  81     {0.0, 3.0, 3.0, 0.0};
  82     GLfloat local_view[] =
  83     {0.0};
  84
  85     glEnable(GL_DEPTH_TEST);
  86     glDepthFunc(GL_LESS);
  87
  88     glLightfv(GL_LIGHT0, GL_POSITION, position);
  89     glLightModelfv(GL_LIGHT_MODEL_LOCAL_VIEWER, local_view);
  90
  91     glFrontFace(GL_CW);
  92     glEnable(GL_LIGHTING);
  93     glEnable(GL_LIGHT0);
  94     glEnable(GL_AUTO_NORMAL);
  95     glEnable(GL_NORMALIZE);
  96     glEnable(GL_FOG);
  97     {
  98         GLfloat fogColor[4] =
  99         {0.5, 0.5, 0.5, 1.0};
 100
 101         fogMode = GL_EXP;
 102         glFogi(GL_FOG_MODE, fogMode);
 103         glFogfv(GL_FOG_COLOR, fogColor);
 104         glFogf(GL_FOG_DENSITY, 0.35);
 105         glHint(GL_FOG_HINT, GL_DONT_CARE);
 106         glClearColor(0.5, 0.5, 0.5, 1.0);
 107     }
 108 }
 109
 110 void
 111 renderRedTeapot(GLfloat x, GLfloat y, GLfloat z)
 112 {
 113     float mat[4];
 114
 115     glPushMatrix();
 116     glTranslatef(x, y, z);
 117     mat[0] = 0.1745;
 118     mat[1] = 0.01175;
 119     mat[2] = 0.01175;
 120     mat[3] = 1.0;
 121     glMaterialfv(GL_FRONT, GL_AMBIENT, mat);
 122     mat[0] = 0.61424;
 123     mat[1] = 0.04136;
 124     mat[2] = 0.04136;
 125     glMaterialfv(GL_FRONT, GL_DIFFUSE, mat);
 126     mat[0] = 0.727811;
 127     mat[1] = 0.626959;
 128     mat[2] = 0.626959;
 129     glMaterialfv(GL_FRONT, GL_SPECULAR, mat);
 130     glMaterialf(GL_FRONT, GL_SHININESS, 0.6 * 128.0);
 131     glutSolidTeapot(1.0);
 132     glPopMatrix();
 133 }
 134
 135 /*  display() draws 5 teapots at different z positions.
 136  */
 137 void
 138 display(void)
 139 {
 140     glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
 141     renderRedTeapot(-4.0, -0.5, -1.0);
 142     renderRedTeapot(-2.0, -0.5, -2.0);
 143     renderRedTeapot(0.0, -0.5, -3.0);
 144     renderRedTeapot(2.0, -0.5, -4.0);
 145     renderRedTeapot(4.0, -0.5, -5.0);
 146     glFlush();
 147 }
 148
 149 void
 150 myReshape(int w, int h)
 151 {
 152     glViewport(0, 0, w, h);
 153     glMatrixMode(GL_PROJECTION);
 154     glLoadIdentity();
 155     if (w <= (h * 3))
 156         glOrtho(-6.0, 6.0, -2.0 * ((GLfloat) h * 3) / (GLfloat) w,
 157             2.0 * ((GLfloat) h * 3) / (GLfloat) w, 0.0, 10.0);
 158     else
 159         glOrtho(-6.0 * (GLfloat) w / ((GLfloat) h * 3),
 160             6.0 * (GLfloat) w / ((GLfloat) h * 3), -2.0, 2.0, 0.0, 10.0);
 161     glMatrixMode(GL_MODELVIEW);
 162     glLoadIdentity();
 163 }
 164
 165 static void
 166 key(unsigned char k, int x, int y)
 167 {
 168   switch (k) {
 169   case 27:  /* Escape */
 170     exit(0);
 171     break;
 172   default:
 173     return;
 174   }
 175   glutPostRedisplay();
 176 }
 177
 178 /*  Main Loop
 179  *  Open window with initial window size, title bar,
 180  *  RGBA display mode, depth buffer, and handle input events.
 181  */
 182 int
 183 main(int argc, char **argv)
 184 {
 185     glutInit(&argc, argv);
 186     glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
 187     glutInitWindowSize(450, 150);
 188     glutCreateWindow(argv[0]);
 189     myinit();
 190     glutReshapeFunc(myReshape);
 191     glutDisplayFunc(display);
 192     glutCreateMenu(selectFog);
 193     glutAddMenuEntry("Fog EXP", GL_EXP);
 194     glutAddMenuEntry("Fog EXP2", /*GL_EXP2*/ 0xffff);
 195     glutAddMenuEntry("Fog LINEAR", GL_LINEAR);
 196     glutAddMenuEntry("Quit", 0);
 197     glutAttachMenu(GLUT_RIGHT_BUTTON);
 198     glutKeyboardFunc(key);
 199     glutMainLoop();
 200     return 0;             /* ANSI C requires main to return int. */
 201 }