Modify fig24_01.py so that it allows users to start rotation, stop rotation and change the rotation direction.

Question

What will be an ideal response?

Answer 1

```
# Colored, rotating box (with open top and bottom).

from Tkinter import *
from OpenGL.GL import *
from OpenGL.Tk import *
import Pmw
import sys

class ColorBox( Frame ):
"""A colored, rotating box"""

def __init__( self ):
"""Initialize GUI and OpenGL"""

Frame.__init__( self )
Pmw.initialise()
self.master.title( "Color Box" )
self.master.geometry( "300x300" )
self.pack( expand = YES, fill = BOTH )

# create stop, start and change direction buttons
self.buttonBox = Pmw.ButtonBox( self, labelpos = "n",
frame_borderwidth = 2, frame_relief = "groove" )
self.buttonBox.pack( padx = 10, pady = 10 )
self.buttonBox.add( "Start", command = self.start )
self.buttonBox.add( "Change Rotation Direction",
command = self.changeDirection )
self.buttonBox.add( "Stop", command = self.stop )

# create and pack Opengl -- use double buffering
self.openGL = Opengl( self, double = 1 )
self.openGL.pack( expand = YES, fill = BOTH )

self.openGL.redraw = self.redraw # set redraw function
self.openGL.set_eyepoint( 20 ) # move away from object

self.increment = 2 # rotate amount
self.stoped = 1 # rotate status

def redraw( self, openGL ):
"""Draw box on black background"""

# clear background and disable lighting
glClearColor( 0.0, 0.0, 0.0, 0.0 ) # select clear color
glClear( GL_COLOR_BUFFER_BIT ) # paint background
glDisable( GL_LIGHTING )

# constants
red = ( 1.0, 0.0, 0.0 )
green = ( 0.0, 1.0, 0.0 )
blue = ( 0.0, 0.0, 1.0 )
purple = ( 1.0, 0.0, 1.0 )

vertices = \
[ ( ( -3.0, 3.0, -3.0 ), red ),
( ( -3.0, -3.0, -3.0 ), green ),
( ( 3.0, 3.0, -3.0 ), blue ),
( ( 3.0, -3.0, -3.0 ), purple ),
( ( 3.0, 3.0, 3.0 ), red ),
( ( 3.0, -3.0, 3.0 ), green ),
( ( -3.0, 3.0, 3.0 ), blue ),
( ( -3.0, -3.0, 3.0 ), purple ),
( ( -3.0, 3.0, -3.0 ), red ),
( ( -3.0, -3.0, -3.0 ), green ) ]

glBegin( GL_QUAD_STRIP ) # begin drawing

# change color and plot point for each vertex
for vertex in vertices:
location, color = vertex
apply( glColor3f, color )
apply( glVertex3f, location )

glEnd() # stop drawing
glEnable( GL_LIGHTING ) # re-enable lighting

def update( self ):
"""Rotate box"""

if self.stop > 0:

# rotate box around ( 1.0, 1.0, 1.0 )
glRotate( self.increment, 1.0, 1.0, 1.0 )

self.openGL.tkRedraw() # redraw geometry
self.openGL.after( 10, self.update ) # update in 10ms

def start( self ):
"""Start rotating"""

self.stop = 1
self.increment = 2
self.update()

def stop( self ):
"""Stop rotating"""

self.stop = 0

def changeDirection ( self ):
"""Change rotation direction"""

# check current direction and make corresponding changes
if self.increment == 2:
self.increment = -2
else:
self.increment = 2
self.update()


def main():
ColorBox().mainloop()

if __name__ == "__main__":
main()
```