progs/redbook/fogcoord.c

   1 /*
   2  * Copyright (c) 1993-2003, Silicon Graphics, Inc.
   3  * All Rights Reserved
   4  *
   5  * Permission to use, copy, modify, and distribute this software for any
   6  * purpose and without fee is hereby granted, provided that the above
   7  * copyright notice appear in all copies and that both the copyright
   8  * notice and this permission notice appear in supporting documentation,
   9  * and that the name of Silicon Graphics, Inc. not be used in
  10  * advertising or publicity pertaining to distribution of the software
  11  * without specific, written prior permission.
  12  *
  13  * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS" AND
  14  * WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
  16  * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
  17  * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
  18  * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
  19  * OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION, LOSS OF
  20  * PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF THIRD
  21  * PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN ADVISED OF
  22  * THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON ANY THEORY OF
  23  * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE POSSESSION, USE
  24  * OR PERFORMANCE OF THIS SOFTWARE.
  25  *
  26  * US Government Users Restricted Rights
  27  * Use, duplication, or disclosure by the Government is subject to
  28  * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
  29  * (c)(1)(ii) of the Rights in Technical Data and Computer Software
  30  * clause at DFARS 252.227-7013 and/or in similar or successor clauses
  31  * in the FAR or the DOD or NASA FAR Supplement.  Unpublished - rights
  32  * reserved under the copyright laws of the United States.
  33  *
  34  * Contractor/manufacturer is:
  35  *      Silicon Graphics, Inc.
  36  *      1500 Crittenden Lane
  37  *      Mountain View, CA  94043
  38  *      United State of America
  39  *
  40  * OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
  41  */
  42
  43 /*
  44  *  fogcoord.c
  45  *
  46  *  This program demonstrates the use of explicit fog
  47  *  coordinates.  You can press the keyboard and change
  48  *  the fog coordinate value at any vertex.  You can
  49  *  also switch between using explicit fog coordinates
  50  *  and the default fog generation mode.
  51  *
  52  *  Pressing the 'f' and 'b' keys move the viewer forward
  53  *  and backwards.
  54  *  Pressing 'c' initiates the default fog generation.
  55  *  Pressing capital 'C' restores explicit fog coordinates.
  56  *  Pressing '1', '2', '3', '8', '9', and '0' add or
  57  *  subtract from the fog coordinate values at one of the
  58  *  three vertices of the triangle.
  59  */
  60
  61 #include <GL/glew.h>
  62 #include <GL/glut.h>
  63 #include <math.h>
  64 #include <stdlib.h>
  65 #include <stdio.h>
  66
  67 static GLfloat f1, f2, f3;
  68
  69 /*  Initialize fog
  70  */
  71 static void init(void)
  72 {
  73    GLfloat fogColor[4] = {0.0, 0.25, 0.25, 1.0};
  74    f1 = 1.0f;
  75    f2 = 5.0f;
  76    f3 = 10.0f;
  77
  78    glEnable(GL_FOG);
  79    glFogi (GL_FOG_MODE, GL_EXP);
  80    glFogfv (GL_FOG_COLOR, fogColor);
  81    glFogf (GL_FOG_DENSITY, 0.25);
  82    glHint (GL_FOG_HINT, GL_DONT_CARE);
  83    glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FOG_COORDINATE_EXT);
  84    glClearColor(0.0, 0.25, 0.25, 1.0);  /* fog color */
  85 }
  86
  87 /* display() draws a triangle at an angle.
  88  */
  89 static void display(void)
  90 {
  91    glClear(GL_COLOR_BUFFER_BIT);
  92
  93    glColor3f (1.0f, 0.75f, 0.0f);
  94    glBegin (GL_TRIANGLES);
  95    glFogCoordfEXT (f1);
  96    glVertex3f (2.0f, -2.0f, 0.0f);
  97    glFogCoordfEXT (f2);
  98    glVertex3f (-2.0f, 0.0f, -5.0f);
  99    glFogCoordfEXT (f3);
 100    glVertex3f (0.0f, 2.0f, -10.0f);
 101    glEnd();
 102
 103    glutSwapBuffers();
 104 }
 105
 106 static void reshape(int w, int h)
 107 {
 108    glViewport(0, 0, (GLsizei) w, (GLsizei) h);
 109    glMatrixMode(GL_PROJECTION);
 110    glLoadIdentity();
 111    gluPerspective (45.0, 1.0, 0.25, 25.0);
 112    glMatrixMode(GL_MODELVIEW);
 113    glLoadIdentity ();
 114    glTranslatef (0.0, 0.0, -5.0);
 115 }
 116
 117 static void keyboard(unsigned char key, int x, int y)
 118 {
 119    switch (key) {
 120       case 'c':
 121          glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FRAGMENT_DEPTH_EXT);
 122          glutPostRedisplay();
 123          break;
 124       case 'C':
 125          glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FOG_COORDINATE_EXT);
 126          glutPostRedisplay();
 127          break;
 128       case '1':
 129          f1 = f1 + 0.25;
 130          glutPostRedisplay();
 131          break;
 132       case '2':
 133          f2 = f2 + 0.25;
 134          glutPostRedisplay();
 135          break;
 136       case '3':
 137          f3 = f3 + 0.25;
 138          glutPostRedisplay();
 139          break;
 140       case '8':
 141          if (f1 > 0.25) {
 142             f1 = f1 - 0.25;
 143             glutPostRedisplay();
 144          }
 145          break;
 146       case '9':
 147          if (f2 > 0.25) {
 148             f2 = f2 - 0.25;
 149             glutPostRedisplay();
 150          }
 151          break;
 152       case '0':
 153          if (f3 > 0.25) {
 154             f3 = f3 - 0.25;
 155             glutPostRedisplay();
 156          }
 157          break;
 158       case 'b':
 159          glMatrixMode (GL_MODELVIEW);
 160          glTranslatef (0.0, 0.0, -0.25);
 161          glutPostRedisplay();
 162          break;
 163       case 'f':
 164          glMatrixMode (GL_MODELVIEW);
 165          glTranslatef (0.0, 0.0, 0.25);
 166          glutPostRedisplay();
 167          break;
 168       case 27:
 169          exit(0);
 170          break;
 171       default:
 172          break;
 173    }
 174 }
 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 main(int argc, char** argv)
 182 {
 183    glutInit(&argc, argv);
 184    glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);
 185    glutInitWindowSize(500, 500);
 186    glutCreateWindow(argv[0]);
 187    glewInit();
 188    init();
 189    glutReshapeFunc (reshape);
 190    glutKeyboardFunc (keyboard);
 191    glutDisplayFunc (display);
 192    glutMainLoop();
 193    return 0;
 194 }