/*
 * (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 * Unpublished-- rights reserved under the copyright laws of the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.
 */
/*
 *  aim.c
 *  This program calculates the fovy (field of view angle
 *  in the y direction), by using trigonometry, given the
 *  size of an object and its size.
 */
#include <GL/gl.h>
#include <GL/glu.h>
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <GL/glaux.h>

void myinit(void)
{
  glShadeModel(GL_FLAT);
}

/*
 * Clear the screen.  Set the current color to white.
 * *  Draw the wire frame cube and sphere.
 */
void display(void)
{
  glClear(GL_COLOR_BUFFER_BIT);
  glColor3f(1.0, 1.0, 1.0);

  glLoadIdentity();
/*
 * glTranslatef() as viewing transformation     
 */
  glTranslatef(0.0, 0.0, -5.0);
  auxWireCube(2.0);
  auxWireSphere(1.0);
  glFlush();
}

#ifndef PI
#define PI  3.1415926535
#endif

/*
 * atan2 () is a system math routine which calculates
 * *  the arctangent of an angle, given length of the 
 * *  opposite and adjacent sides of a right triangle.
 * *  atan2 () is not an OpenGL routine.
 */
GLdouble calculateAngle(double size, double distance)
{
  GLdouble radtheta, degtheta;

  radtheta = 2.0 * atan2(size / 2.0, distance);
  degtheta = (180.0 * radtheta) / PI;
  printf("degtheta is %f\n", degtheta);
  return ((GLdouble) degtheta);
}

/*
 * Called when the window is first opened and whenever 
 * *  the window is reconfigured (moved or resized).
 */
void myReshape(int w, int h)
{
  GLdouble theta;

  glViewport(0, 0, w, h);
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  theta = calculateAngle(2.0, 5.0);
  gluPerspective(theta, (GLfloat) w / (GLfloat) h, 1.0, 20.0);
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
}

/*
 * 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);
  auxInitPosition(0, 0, 500, 500);
  if (!auxInitWindow(argv[0]))
    auxQuit();
  myinit();
  auxReshapeFunc(myReshape);
  auxMainLoop(display);
  return 0;
}