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Python Open Source » Development » PyObjC 
PyObjC » trunk » pyobjc » PyOpenGL 2.0.2.01 » OpenGL » Demo » NeHe » lesson13.py
#!


#
# Ported to PyOpenGL 2.0 by Brian Leair 18 Jan 2004
#
# This code was created by Jeff Molofee 2000
#
# The port was based on the PyOpenGL tutorial and from the PyOpenGLContext (tests/glprint.py)
#
# If you've found this code useful, please let me know (email Brian Leair at telcom_sage@yahoo.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.
#
#
from OpenGL.GL import *
from OpenGL.GLUT import *
from OpenGL.GLU import *
from OpenGL.WGL import *# wglUseFontBitmaps (), wglGetCurrentDC ()
win32ui# CreateFont (), CreateDCFromHandle ()
# import Numeric
frommathcos,sin
import sys


# *********************** Globals *********************** 
# Python 2.2 defines these directly
try:
  True
except NameError:
  True = 1==1
  False = 1==0


# 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
base = None


def BuildFont ():
  global base

  wgldc = wglGetCurrentDC ()
  hDC = win32ui.CreateDCFromHandle (wgldc)


  base = glGenLists(32+96);          # // Storage For 96 Characters, plus 32 at the start...

  # CreateFont () takes a python dictionary to specify the requested font properties. 
  font_properties = { "name" : "Courier New",
            "width" : 0 ,
            "height" : -24,
            "weight" : 800
            }
  font = win32ui.CreateFont (font_properties)
  # // Selects The Font We Want
  oldfont = hDC.SelectObject (font)
  # // Builds 96 Characters Starting At Character 32
  wglUseFontBitmaps (wgldc, 32, 96, base+32)
  # // reset the font
  hDC.SelectObject (oldfont)
  # // Delete The Font (python will cleanup font for us...)
  return

def KillFont ():
  """ // Delete The Font List
  """
  global  base
  # // Delete All 96 Characters
  glDeleteLists (base, 32+96)
  return


def glPrint (str):
  """ // Custom GL "Print" Routine
  """
  global base
  # // If THere's No Text Do Nothing
  if (str == None):
    return
  if (str == ""):
    return
  glPushAttrib(GL_LIST_BIT);              # // Pushes The Display List Bits
  try:
    glListBase(base);                # // Sets The Base Character to 32
    glCallLists(str)                  # // Draws The Display List Text
  finally:
    glPopAttrib();                    # // Pops The Display List Bits
  return


# 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.
  glShadeModel(GL_SMOOTH)        # Enables Smooth Color Shading
  glClearColor(0.0, 0.0, 0.0, 0.5)  # This Will Clear The Background Color To Black
  glClearDepth(1.0)          # Enables Clearing Of The Depth Buffer
  glEnable(GL_DEPTH_TEST)        # Enables Depth Testing
  glDepthFunc(GL_LEQUAL)        # The Type Of Depth Test To Do
  glHint (GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST) # Really Nice Perspective Calculations

  BuildFont ()
  return True
  

# 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()
  # // field of view, aspect ratio, near and far
  # This will squash and stretch our objects as the window is resized.
  gluPerspective(45.0, float(Width)/float(Height), 0.1, 100.0)

  glMatrixMode(GL_MODELVIEW)
  glLoadIdentity()



cnt1 = 0
cnt2 = 0
# The main drawing function. 
def DrawGLScene():
  global cnt1
  global cnt2

  # // Clear The Screen And The Depth Buffer
  glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
  
  glLoadIdentity()          # // Reset The Current Modelview Matrix
  glTranslatef (0.0, 0.0, -1.0)    # // Move One Unit Into The Screen

  # // Pulsing Colors Based On Text Position
  glColor3f (1.0 * cos (cnt1), 1.0 * sin (cnt2), 1.0 -0.5 * cos (cnt1+cnt2))
  # // Position The Text On The Screen
  glRasterPos2f(-0.45+0.05* cos(cnt1), 0.32*sin(cnt2));
   glPrint("Active OpenGL Text With NeHe - %7.2f" %(cnt1));  # // Print GL Text To The Screen
  cnt1+=0.051;                    # // Increase The First Counter
  cnt2+=0.005;                    # // Increase The First Counter
  glutSwapBuffers()
  return True


# 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:
    KillFont ()
    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_ALPHA | 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, 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("NeHe's Bitmap Font Tutorial")

     # 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)

  # We've told Glut the type of window we want, and we've told glut about
  # various functions that we want invoked (idle, resizing, keyboard events).
  # Glut has done the hard work of building up thw windows DC context and 
  # tying in a rendering context, so we are ready to start making immediate mode
  # GL calls.
  # Call to perform inital GL setup (the clear colors, enabling modes, and most releveant -
  # consturct the displays lists for the bitmap font.
  InitGL(640, 480)

  # Start Event Processing Engine  
  glutMainLoop()

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

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