www.pudn.com > openglbk.rar > fogindex.c

/* 
 * Copyright (c) 1993-1999, 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 * Unpublished-- rights reserved under the copyright laws of the 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., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311. 
 * 
 * OpenGL(R) is a registered trademark of Silicon Graphics, Inc. 
 */ 
 
/* 
 *  fogindex.c 
 *  This program draws 5 wireframe spheres, each at  
 *  a different z distance from the eye, in linear fog. 
 */ 
#include  
#include  
#include  
#include  
 
/*  Initialize color map and fog.  Set screen clear color 
 *  to end of color ramp. 
 */ 
#define NUMCOLORS 32 
#define RAMPSTART 16 
 
static void init(void) 
{ 
   int i; 
 
   glEnable(GL_DEPTH_TEST); 
 
   for (i = 0; i < NUMCOLORS; i++) { 
      GLfloat shade; 
      shade = (GLfloat) (NUMCOLORS-i)/(GLfloat) NUMCOLORS; 
      glutSetColor (RAMPSTART + i, shade, shade, shade); 
   } 
   glEnable(GL_FOG); 
 
   glFogi (GL_FOG_MODE, GL_LINEAR); 
   glFogi (GL_FOG_INDEX, NUMCOLORS); 
   glFogf (GL_FOG_START, 1.0); 
   glFogf (GL_FOG_END, 6.0); 
   glHint (GL_FOG_HINT, GL_NICEST); 
   glClearIndex((GLfloat) (NUMCOLORS+RAMPSTART-1)); 
} 
 
static void renderSphere (GLfloat x, GLfloat y, GLfloat z) 
{ 
   glPushMatrix(); 
   glTranslatef (x, y, z); 
   glutWireSphere(0.4, 16, 16); 
   glPopMatrix(); 
} 
 
/*  display() draws 5 spheres at different z positions. 
 */ 
void display(void) 
{ 
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); 
   glIndexi (RAMPSTART); 
 
   renderSphere (-2., -0.5, -1.0); 
   renderSphere (-1., -0.5, -2.0); 
   renderSphere (0., -0.5, -3.0); 
   renderSphere (1., -0.5, -4.0); 
   renderSphere (2., -0.5, -5.0); 
 
   glFlush(); 
} 
 
void reshape(int w, int h) 
{ 
   glViewport(0, 0, w, h); 
   glMatrixMode(GL_PROJECTION); 
   glLoadIdentity(); 
   if (w <= h) 
      glOrtho (-2.5, 2.5, -2.5*(GLfloat)h/(GLfloat)w, 
         2.5*(GLfloat)h/(GLfloat)w, -10.0, 10.0); 
   else 
      glOrtho (-2.5*(GLfloat)w/(GLfloat)h, 
         2.5*(GLfloat)w/(GLfloat)h, -2.5, 2.5, -10.0, 10.0); 
   glMatrixMode(GL_MODELVIEW); 
   glLoadIdentity (); 
} 
 
void keyboard(unsigned char key, int x, int y) 
{ 
 
   switch (key) { 
      case 27: 
         exit(0); 
   } 
} 
 
 
/*  Main Loop 
 *  Open window with initial window size, title bar,  
 *  color index mode, depth buffer, and handle input events. 
 */ 
int main(int argc, char** argv) 
{ 
   glutInit(&argc, argv); 
   glutInitDisplayMode (GLUT_SINGLE | GLUT_INDEX | GLUT_DEPTH); 
   glutInitWindowSize(500, 500); 
   glutCreateWindow(argv[0]); 
   init(); 
   glutReshapeFunc (reshape); 
   glutKeyboardFunc (keyboard); 
   glutDisplayFunc (display); 
   glutMainLoop(); 
   return 0; 
}