from __future__ import print_function, division
from visual import *
scene.height = 800
scene.width = 800
scene.background = color.white

wheel = frame()
th = 0.5
y0 = -5
R = 10.
M = 0.07
s = cylinder(pos = (0,y0-th/2,0), color=color.cyan, radius=R, axis=(0,th,0), frame=wheel)
b = box(pos=(0,y0,0),color=color.red, size=(2*R,th+.2,th+.2), frame=wheel)
##lbar = arrow(pos=(20,y0,0), color=color.magenta, axis = (0,1,0), shaftwidth = 2*th)
lbar = arrow(pos=s.pos, color=color.magenta, axis = (0,1,0), shaftwidth = 2*th)
t = 0
dt = 0.01
domega = 2*pi/3.
omega = pi
L = 0.5*M*R**2*omega
lbar.axis = (0,L,0)
scene.range=30
scene.autoscale = 0

while t < 100:
    rate(100)
    wheel.rotate(angle=omega*dt, axis = (0,1,0))
    t = t + dt
    if scene.mouse.clicked:
        mm = scene.mouse.getclick()
        omega = omega - domega
        L = 0.5*M*R**2*omega
        lbar.axis = (0,L,0)
        if (omega < -pi) or (omega > pi):
            domega = -domega