/*
 * (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 * Unpublished-- rights reserved under the copyright laws of the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.
 */
/*
 *  fogindex.c
 *  This program demonstrates fog in color index mode.  
 *  Three cones are drawn at different z values in a linear 
 *  fog.  32 contiguous colors (from 16 to 47) are loaded 
 *  with a color ramp.
 */
#include <GL/gl.h>
#include <GL/glu.h>
#include <stdlib.h>
#include "glaux.h"

/*  Initialize color map and fog.  Set screen clear color 
 *  to end of color ramp.
 */
#define NUMCOLORS 32
#define RAMPSTART 16

void myinit(void)
{
    int i;

    glEnable(GL_DEPTH_TEST);
    glDepthFunc(GL_LESS);
    for (i = 0; i < NUMCOLORS; i++) {
	GLfloat shade;
	shade = (GLfloat) (NUMCOLORS-i)/(GLfloat) NUMCOLORS;
	auxSetOneColor (16 + i, shade, shade, shade);
    }
    glEnable(GL_FOG);

    glFogi (GL_FOG_MODE, GL_LINEAR);
    glFogi (GL_FOG_INDEX, NUMCOLORS);
    glFogf (GL_FOG_START, 0.0);
    glFogf (GL_FOG_END, 4.0);
    glHint (GL_FOG_HINT, GL_NICEST);
    glClearIndex((GLfloat) (NUMCOLORS+RAMPSTART-1));
}

/*  display() renders 3 cones at different z positions.
 */
void display(void)
{
    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glPushMatrix ();
    glTranslatef (-1.0, -1.0, -1.0);
    glRotatef (-90.0, 1.0, 0.0, 0.0);
    glIndexi (RAMPSTART);
    auxSolidCone(1.0, 2.0);
    glPopMatrix ();

    glPushMatrix ();
    glTranslatef (0.0, -1.0, -2.25);
    glRotatef (-90.0, 1.0, 0.0, 0.0);
    glIndexi (RAMPSTART);
    auxSolidCone(1.0, 2.0);
    glPopMatrix ();

    glPushMatrix ();
    glTranslatef (1.0, -1.0, -3.5);
    glRotatef (-90.0, 1.0, 0.0, 0.0);
    glIndexi (RAMPSTART);
    auxSolidCone(1.0, 2.0);
    glPopMatrix ();
    glFlush();
}

void myReshape(int w, int h)
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    if (w <= h)
	glOrtho (-2.0, 2.0, -2.0*(GLfloat)h/(GLfloat)w, 
	    2.0*(GLfloat)h/(GLfloat)w, 0.0, 10.0);
    else
	glOrtho (-2.0*(GLfloat)w/(GLfloat)h, 
	    2.0*(GLfloat)w/(GLfloat)h, -2.0, 2.0, 0.0, 10.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity ();
}

/*  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)
{
    auxInitDisplayMode (AUX_SINGLE | AUX_INDEX | AUX_DEPTH);
    auxInitPosition (0, 0, 200, 200);
    auxInitWindow (argv[0]);
    myinit();
    auxReshapeFunc (myReshape);
    auxMainLoop(display);
}

