Fog is used to achieve this effect.
/* Copyright (c) Mark J. Kilgard, 1994. */ /* * (c) Copyright 1993, 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 * Unpublished-- rights reserved under the copyright laws of the * United States.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(TM) is a trademark of Silicon Graphics, Inc. */ #include <GL/openglut.h> #include <stdlib.h> /* Initialize linear fog for depth cueing. */ void myinit(void) { GLfloat fogColor[4] = {0.0, 0.0, 0.0, 1.0}; glEnable(GL_FOG); glFogi (GL_FOG_MODE, GL_LINEAR); glHint (GL_FOG_HINT, GL_NICEST); /* per pixel */ glFogf (GL_FOG_START, 3.0); glFogf (GL_FOG_END, 5.0); glFogfv (GL_FOG_COLOR, fogColor); glClearColor(0.0, 0.0, 0.0, 1.0); glDepthFunc(GL_LESS); glEnable(GL_DEPTH_TEST); glShadeModel(GL_FLAT); } /* display() draws an icosahedron. */ void display(void) { glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glColor3f (1.0, 1.0, 1.0); glutWireIcosahedron(); glFlush(); } void myReshape(int w, int h) { glViewport(0, 0, w, h); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective (45.0, (GLfloat) w/(GLfloat) h, 3.0, 5.0); glMatrixMode(GL_MODELVIEW); glLoadIdentity (); glTranslatef (0.0, 0.0, -4.0); /* move object into view */ } static void key(unsigned char k, int x, int y) { switch (k) { case 27: /* Escape */ exit(0); break; default: return; } glutPostRedisplay(); } /* Main Loop */ int main(int argc, char** argv) { glutInit(&argc, argv); glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH); glutCreateWindow(argv[0]); myinit(); glutReshapeFunc(myReshape); glutDisplayFunc(display); glutKeyboardFunc(key); glutMainLoop(); return 0; /* ANSI C requires main to return int. */ }