#!/usr/local/bin/python2.5

# 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 * Unpublished-- rights reserved under the copyright laws of the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)
	glutSwapBuffers()

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()


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

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

if __name__ == "__main__":
	main()

