fogcoord.c revision 32001f49 
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  Unpublished - rights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 "glut_wrap.h"
63#include <math.h>
64#include <stdlib.h>
65#include <stdio.h>
66
67static GLfloat f1, f2, f3;
68
69/*  Initialize fog
70 */
71static 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 */
89static 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
106static 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
117static 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 */
181int 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}
195