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Python Open Source » Development » PyObjC 
PyObjC » trunk » pyobjc » PyOpenGL 2.0.2.01 » OpenGL » Demo » NeHe » lesson3.py
#!

# 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 

  # Move Left 1.5 units and into the screen 6.0 units.
  glTranslatef(-1.5, 0.0, -6.0)

  # Since we have smooth color mode on, this will be great for the Phish Heads :-).
  # Draw a triangle
  glBegin(GL_POLYGON)                 # Start drawing a polygon
  glColor3f(1.0, 0.0, 0.0)            # Red
  glVertex3f(0.0, 1.0, 0.0)           # Top
  glColor3f(0.0, 1.0, 0.0)            # Green
  glVertex3f(1.0, -1.0, 0.0)          # Bottom Right
  glColor3f(0.0, 0.0, 1.0)            # Blue
  glVertex3f(-1.0, -1.0, 0.0)         # Bottom Left
  glEnd()                             # We are done with the polygon


  # Move Right 3.0 units.
  glTranslatef(3.0, 0.0, 0.0)

  # Draw a square (quadrilateral)
  glColor3f(0.3, 0.5, 1.0)            # Bluish shade
  glBegin(GL_QUADS)                   # Start drawing a 4 sided polygon
  glVertex3f(-1.0, 1.0, 0.0)          # Top Left
  glVertex3f(1.0, 1.0, 0.0)           # Top Right
  glVertex3f(1.0, -1.0, 0.0)          # Bottom Right
  glVertex3f(-1.0, -1.0, 0.0)         # Bottom Left
  glEnd()                             # We are done with the polygon

  #  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):
  # If escape is pressed, kill everything.
    if args[0] == ESCAPE:
      sys.exit()

def main():
  global window
  # For now we just pass glutInit one empty argument. I wasn't sure what should or could be passed in (tuple, list, ...)
  # Once I find out the right stuff based on reading the PyOpenGL source, I'll address this.
  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()
      
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