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/*
* Copyright (c) 1993-2003, Silicon Graphics, Inc.
* All Rights Reserved
*
* Permission to use, copy, modify, and distribute this software for any
* purpose and without fee is hereby granted, provided that the above
* copyright notice appear in all copies and that both the copyright
* notice and this permission notice appear in supporting documentation,
* and that the name of Silicon Graphics, Inc. not be used in
* advertising or publicity pertaining to distribution of the software
* without specific, written prior permission.
*
* THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS" AND
* WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
* FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL SILICON
* GRAPHICS, INC. BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
* SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
* OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION, LOSS OF
* PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF THIRD
* PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC. HAS BEEN ADVISED OF
* THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE POSSESSION, USE
* OR PERFORMANCE OF THIS SOFTWARE.
*
* US Government Users Restricted Rights
* Use, duplication, or disclosure by the Government is subject to
* restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
* (c)(1)(ii) of the Rights in Technical Data and Computer Software
* clause at DFARS 252.227-7013 and/or in similar or successor clauses
* in the FAR or the DOD or NASA FAR Supplement. Unpublished - rights
* reserved under the copyright laws of the United States.
*
* Contractor/manufacturer is:
* Silicon Graphics, Inc.
* 1500 Crittenden Lane
* Mountain View, CA 94043
* United State of America
*
* OpenGL(R) is a registered trademark of Silicon Graphics, Inc.
*/
/*
* fogcoord.c
*
* This program demonstrates the use of explicit fog
* coordinates. You can press the keyboard and change
* the fog coordinate value at any vertex. You can
* also switch between using explicit fog coordinates
* and the default fog generation mode.
*
* Pressing the 'f' and 'b' keys move the viewer forward
* and backwards.
* Pressing 'c' initiates the default fog generation.
* Pressing capital 'C' restores explicit fog coordinates.
* Pressing '1', '2', '3', '8', '9', and '0' add or
* subtract from the fog coordinate values at one of the
* three vertices of the triangle.
*/
#define GL_GLEXT_PROTOTYPES
#include <GL/glut.h>
#include <math.h>
#include <stdlib.h>
#include <stdio.h>
static GLfloat f1, f2, f3;
/* Initialize fog
*/
static void init(void)
{
GLfloat fogColor[4] = {0.0, 0.25, 0.25, 1.0};
f1 = 1.0f;
f2 = 5.0f;
f3 = 10.0f;
glEnable(GL_FOG);
glFogi (GL_FOG_MODE, GL_EXP);
glFogfv (GL_FOG_COLOR, fogColor);
glFogf (GL_FOG_DENSITY, 0.25);
glHint (GL_FOG_HINT, GL_DONT_CARE);
glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FOG_COORDINATE_EXT);
glClearColor(0.0, 0.25, 0.25, 1.0); /* fog color */
}
/* display() draws a triangle at an angle.
*/
static void display(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glColor3f (1.0f, 0.75f, 0.0f);
glBegin (GL_TRIANGLES);
glFogCoordfEXT (f1);
glVertex3f (2.0f, -2.0f, 0.0f);
glFogCoordfEXT (f2);
glVertex3f (-2.0f, 0.0f, -5.0f);
glFogCoordfEXT (f3);
glVertex3f (0.0f, 2.0f, -10.0f);
glEnd();
glutSwapBuffers();
}
static void reshape(int w, int h)
{
glViewport(0, 0, (GLsizei) w, (GLsizei) h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective (45.0, 1.0, 0.25, 25.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity ();
glTranslatef (0.0, 0.0, -5.0);
}
static void keyboard(unsigned char key, int x, int y)
{
switch (key) {
case 'c':
glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FRAGMENT_DEPTH_EXT);
glutPostRedisplay();
break;
case 'C':
glFogi(GL_FOG_COORDINATE_SOURCE_EXT, GL_FOG_COORDINATE_EXT);
glutPostRedisplay();
break;
case '1':
f1 = f1 + 0.25;
glutPostRedisplay();
break;
case '2':
f2 = f2 + 0.25;
glutPostRedisplay();
break;
case '3':
f3 = f3 + 0.25;
glutPostRedisplay();
break;
case '8':
if (f1 > 0.25) {
f1 = f1 - 0.25;
glutPostRedisplay();
}
break;
case '9':
if (f2 > 0.25) {
f2 = f2 - 0.25;
glutPostRedisplay();
}
break;
case '0':
if (f3 > 0.25) {
f3 = f3 - 0.25;
glutPostRedisplay();
}
break;
case 'b':
glMatrixMode (GL_MODELVIEW);
glTranslatef (0.0, 0.0, -0.25);
glutPostRedisplay();
break;
case 'f':
glMatrixMode (GL_MODELVIEW);
glTranslatef (0.0, 0.0, 0.25);
glutPostRedisplay();
break;
case 27:
exit(0);
break;
default:
break;
}
}
/* Main Loop
* Open window with initial window size, title bar,
* RGBA display mode, depth buffer, and handle input events.
*/
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode (GLUT_DOUBLE | GLUT_RGB);
glutInitWindowSize(500, 500);
glutCreateWindow(argv[0]);
init();
glutReshapeFunc (reshape);
glutKeyboardFunc (keyboard);
glutDisplayFunc (display);
glutMainLoop();
return 0;
}
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