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

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

import string
__version__ = string.split('$Revision: 1.8 $')[1]
__date__ = string.join(string.split('$Date: 2002/12/31 04:13:55 $')[1:3], ' ')
__author__ = 'Tarn Weisner Burton <twburton@users.sourceforge.net>'

#
# Ported to PyOpenGL 2.0 by Tarn Weisner Burton 10May2001
#
# This code was created by Richard Campbell '99 (ported to Python/PyOpenGL by John Ferguson 2000)
#
# The port was based on the PyOpenGL tutorial module: dots.py  
#
# If you've found this code useful, please let me know (email John Ferguson at hakuin@voicenet.com).
#
# See original source and C based tutorial at http://nehe.gamedev.net
#
# Note:
# -----
# This code is not a good example of Python and using OO techniques.  It is a simple and direct
# exposition of how to use the Open GL API in Python via the PyOpenGL package.  It also uses GLUT,
# which in my opinion is a high quality library in that it makes my work simpler.  Due to using
# these APIs, this code is more like a C program using function based programming (which Python
# is in fact based upon, note the use of closures and lambda) than a "good" OO program.
#
# To run this code get and install OpenGL, GLUT, PyOpenGL (see http://www.python.org), and PyNumeric.
# Installing PyNumeric means having a C compiler that is configured properly, or so I found.  For 
# Win32 this assumes VC++, I poked through the setup.py for Numeric, and chased through disutils code
# and noticed what seemed to be hard coded preferences for VC++ in the case of a Win32 OS.  However,
# I am new to Python and know little about disutils, so I may just be not using it right.
#
# BTW, since this is Python make sure you use tabs or spaces to indent, I had numerous problems since I 
# was using editors that were not sensitive to Python.
#
from OpenGL.GL import *
from OpenGL.GLUT import *
from OpenGL.GLU import *
import sys

# Some api in the chain is translating the keystrokes to this octal string
# so instead of saying: ESCAPE = 27, we use the following.
ESCAPE = '\033'

# Number of the glut window.
window = 0

# A general OpenGL initialization function.  Sets all of the initial parameters. 
def InitGL(Width, Height):				# We call this right after our OpenGL window is created.
	glClearColor(0.0, 0.0, 0.0, 0.0)	# This Will Clear The Background Color To Black
	glClearDepth(1.0)					# Enables Clearing Of The Depth Buffer
	glDepthFunc(GL_LESS)				# The Type Of Depth Test To Do
	glEnable(GL_DEPTH_TEST)				# Enables Depth Testing
	glShadeModel(GL_SMOOTH)				# Enables Smooth Color Shading
	
	glMatrixMode(GL_PROJECTION)
	glLoadIdentity()					# Reset The Projection Matrix
										# Calculate The Aspect Ratio Of The Window
	gluPerspective(45.0, float(Width)/float(Height), 0.1, 100.0)

	glMatrixMode(GL_MODELVIEW)

# The function called when our window is resized (which shouldn't happen if you enable fullscreen, below)
def ReSizeGLScene(Width, Height):
	if Height == 0:						# Prevent A Divide By Zero If The Window Is Too Small 
		Height = 1

	glViewport(0, 0, Width, Height)		# Reset The Current Viewport And Perspective Transformation
	glMatrixMode(GL_PROJECTION)
	glLoadIdentity()
	gluPerspective(45.0, float(Width)/float(Height), 0.1, 100.0)
	glMatrixMode(GL_MODELVIEW)

# The main drawing function. 
def DrawGLScene():
	# Clear The Screen And The Depth Buffer
	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
	glLoadIdentity()					# Reset The View 

	#  since this is double buffered, swap the buffers to display what just got drawn. 
	glutSwapBuffers()

# The function called whenever a key is pressed. Note the use of Python tuples to pass in: (key, x, y)  
def keyPressed(*args):
	global window
	# If escape is pressed, kill everything.
	if args[0] == ESCAPE:
		sys.exit()

def main():
	global window
	# pass arguments to init
	glutInit(sys.argv)

	# Select type of Display mode:   
	#  Double buffer 
	#  RGBA color
	# Alpha components supported 
	# Depth buffer
	glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH)
	
	# get a 640 x 480 window 
	glutInitWindowSize(640, 480)
	
	# the window starts at the upper left corner of the screen 
	glutInitWindowPosition(0, 0)
	
	# Okay, like the C version we retain the window id to use when closing, but for those of you new
	# to Python (like myself), remember this assignment would make the variable local and not global
	# if it weren't for the global declaration at the start of main.
	window = glutCreateWindow("Jeff Molofee's GL Code Tutorial ... NeHe '99")

   	# Register the drawing function with glut, BUT in Python land, at least using PyOpenGL, we need to
	# set the function pointer and invoke a function to actually register the callback, otherwise it
	# would be very much like the C version of the code.	
	glutDisplayFunc(DrawGLScene)
	
	# Uncomment this line to get full screen.
	#glutFullScreen()

	# When we are doing nothing, redraw the scene.
	glutIdleFunc(DrawGLScene)
	
	# Register the function called when our window is resized.
	glutReshapeFunc(ReSizeGLScene)
	
	# Register the function called when the keyboard is pressed.  
	glutKeyboardFunc(keyPressed)

	# Initialize our window. 
	InitGL(640, 480)

	# Start Event Processing Engine	
	glutMainLoop()

# Print message to console, and kick off the main to get it rolling.
print "Hit ESC key to quit."
main()
		
