/*
 * (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 * Unpublished-- rights reserved under the copyright laws of the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.
 */
/*
 *  movelight.c
 *  This program demonstrates when to issue lighting and 
 *  transformation commands to render a model with a light 
 *  which is moved by a modeling transformation (rotate or 
 *  translate).  The light position is reset after the modeling 
 *  transformation is called.  The eye position does not change.
 *
 *  A sphere is drawn using a grey material characteristic. 
 *  A single light source illuminates the object.
 *
 *  Interaction:  pressing the left or middle mouse button
 *  alters the modeling transformation (x rotation) by 30 degrees.  
 *  The scene is then redrawn with the light in a new position.
 */
#include <GL/gl.h>
#include <GL/glu.h>
#include <stdlib.h>
#include "glaux.h"

static int spin = 0;

void movelight (AUX_EVENTREC *event)
{
    spin = (spin + 30) % 360;
}

void myinit (void)
{
    glEnable(GL_LIGHTING);
    glEnable(GL_LIGHT0);

    glDepthFunc(GL_LESS);
    glEnable(GL_DEPTH_TEST);
}

/*  Here is where the light position is reset after the modeling
 *  transformation (glRotated) is called.  This places the 
 *  light at a new position in world coordinates.  The cube
 *  represents the position of the light.
 */
void display(void)
{
    GLfloat position[] = { 0.0, 0.0, 1.5, 1.0 };

    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glPushMatrix ();
    glTranslatef (0.0, 0.0, -5.0); 

    glPushMatrix ();
    glRotated ((GLdouble) spin, 1.0, 0.0, 0.0);
    glRotated (0.0, 1.0, 0.0, 0.0);
    glLightfv (GL_LIGHT0, GL_POSITION, position);

    glTranslated (0.0, 0.0, 1.5);
    glDisable (GL_LIGHTING);
    glColor3f (0.0, 1.0, 1.0);
    auxWireCube (0.1);
    glEnable (GL_LIGHTING);
    glPopMatrix ();

    auxSolidTorus (0.275, 0.85);
    glPopMatrix ();
    glFlush ();
}

void myReshape(int w, int h)
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    gluPerspective(40.0, (GLfloat) w/(GLfloat) h, 1.0, 20.0);
    glMatrixMode(GL_MODELVIEW);
}

/*  Main Loop
 *  Open window with initial window size, title bar, 
 *  RGBA display mode, and handle input events.
 */
int main(int argc, char** argv)
{
    auxInitDisplayMode (AUX_SINGLE | AUX_RGB | AUX_DEPTH);
    auxInitPosition (0, 0, 500, 500);
    if (!auxInitWindow (argv[0]))
       auxQuit();
    myinit();
    auxMouseFunc (AUX_LEFTBUTTON, AUX_MOUSEDOWN, movelight);
    auxReshapeFunc (myReshape);
    auxMainLoop(display);
    return 0;
}






