#!/usr/bin/python

# This is statement is required by the build system to query build info
if __name__ == '__build__':
	raise Exception

'''
fog.c from the Redbook examples.  
Converted to Python by Jason L. Petrone 7/00

/*
 * Copyright (c) 1993-1997, 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 * Unpublished-- rights reserved under the copyright laws of the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.
 */
'''

'''
/*
 *  fog.c
 *  This program draws 5 red spheres, each at a different 
 *  z distance from the eye, in different types of fog.  
 *  Pressing the f key chooses between 3 types of 
 *  fog:  exponential, exponential squared, and linear.  
 *  In this program, there is a fixed density value, as well 
 *  as fixed start and end values for the linear fog.
 */
'''
 
import sys

try:
  from OpenGL.GLUT import *
  from OpenGL.GL import *
except:
  print '''
ERROR: PyOpenGL not installed properly.  
        '''
  sys.exit()


#  Initialize depth buffer, fog, light source, 
#  material property, and lighting model.

def init():
   position = [ 0.5, 0.5, 3.0, 0.0 ]
   glEnable(GL_DEPTH_TEST)
   glLightfv(GL_LIGHT0, GL_POSITION, position)
   glEnable(GL_LIGHTING)
   glEnable(GL_LIGHT0)
   mat = [0.1745, 0.01175, 0.01175, 1.0]
   glMaterialfv(GL_FRONT, GL_AMBIENT, mat)
   mat[0] = 0.61424; mat[1] = 0.04136; mat[2] = 0.04136
   glMaterialfv(GL_FRONT, GL_DIFFUSE, mat)
   mat[0] = 0.727811; mat[1] = 0.626959; mat[2] = 0.626959
   glMaterialfv(GL_FRONT, GL_SPECULAR, mat)
   glMaterialf(GL_FRONT, GL_SHININESS, 0.6*128.0)

   glEnable(GL_FOG)
   fogColor = [0.5, 0.5, 0.5, 1.0]

   global fogMode
   fogMode = GL_EXP
   glFogi (GL_FOG_MODE, fogMode)
   glFogfv (GL_FOG_COLOR, fogColor)
   glFogf (GL_FOG_DENSITY, 0.35)
   glHint (GL_FOG_HINT, GL_DONT_CARE)
   glFogf (GL_FOG_START, 1.0)
   glFogf (GL_FOG_END, 5.0)
   glClearColor(0.5, 0.5, 0.5, 1.0)

def renderSphere(x, y, z):
   glPushMatrix()
   glTranslatef (x, y, z)
   glutSolidSphere(0.4, 16, 16)
   glPopMatrix()

# display() draws 5 spheres at different z positions.
def display():
   glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
   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()

def reshape(w, h):
  glViewport(0, 0, w, h)
  glMatrixMode(GL_PROJECTION)
  glLoadIdentity()
  if (w <= h):
     glOrtho(-2.5, 2.5, -2.5*h/w, 2.5*h/w, -10.0, 10.0)
  else:
     glOrtho(-2.5*w/h, 2.5*w/h, -2.5, 2.5, -10.0, 10.0)
  glMatrixMode(GL_MODELVIEW)
  glLoadIdentity()

def keyboard(key, x, y):
  global fogMode
  if key in ['f','F']:
    if (fogMode == GL_EXP):
      fogMode = GL_EXP2;
      print "Fog mode is GL_EXP2"
    elif (fogMode == GL_EXP2):
      fogMode = GL_LINEAR
      print "Fog mode is GL_LINEAR"
    elif (fogMode == GL_LINEAR):
      fogMode = GL_EXP
      print "Fog mode is GL_EXP"
      glFogi(GL_FOG_MODE, fogMode)
      glutPostRedisplay()
  
  elif ord(key) == 27:
    sys.exit()


#  Main Loop
#  Open window with initial window size, title bar, 
#  RGBA display mode, depth buffer, and handle input events.

glutInit(sys.argv)
glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
glutInitWindowSize(500, 500)
glutCreateWindow('fog')
init()
glutReshapeFunc(reshape)
glutKeyboardFunc(keyboard)
glutDisplayFunc(display)
glutMainLoop()
