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34 * Unpublished-- rights reserved under the copyright laws of the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 "glut_wrap.h"
52
53GLint fogMode;
54
55static void
56selectFog(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 */
76static void
77myinit(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
109static void
110renderRedTeapot(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 */
136static void
137display(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
148static void
149myReshape(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
164static void
165key(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 */
181int
182main(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}
201