from __future__ import division
from visual import *
scene.background = color.white
scene.height = scene.width = 600
scene.x = scene.y = 0

## 
print '''
Set "position" to drop clay with different impact parameters
0=full radius on left, 1=left, 2=top, 3=right, 4=full radius on right
This is mostly a visualization
'''

# clay position 0=full radius on left, 1=left, 2=top, 3=right, 4=full radius on right
position = 0
if position > 4:
    position = 4

# wheel
m = 0.2
w = frame()
bb = []
R = 10
I = 8*m*R**2
for theta in arange(0,2*pi,pi/4):
    b = sphere(pos=(-R*cos(theta), R*sin(theta),0), radius=1.5, color=color.red,
               frame = w)
    bb.append(b)
for b in bb[:4]:
    cylinder(pos=(b.pos), axis = (bb[bb.index(b)+4].pos - b.pos),
             color=(.7,.7,.7), radius = 0.3, frame=w)
axle = cylinder(pos=(0,0,-R/4), axis = (0,0,R/2), radius=1, color=(.7,.7,.7),
                frame=w)

clay = sphere(pos=(bb[position].x,20,0), radius=.5, color=(.7,.5,0))
clay.p = vector(0,-10,0)
clay.m = 0.1
psc = 0.5
clay.pa = arrow(pos=clay.pos, axis=clay.p*psc, color=color.green, visible = 0)
r = (clay.pos - w.pos)
clay.L = cross(r, clay.p)
scene.range = 22

scene.mouse.getclick()
clay.pa.visible = True
# drop clay
dt = 0.01
while clay.y > bb[position].y+2+clay.radius:
    rate(20)
    clay.pos = clay.pos + (clay.p/clay.m)*dt
    clay.pa.pos = clay.pos
clay.frame = w
clay.pa.visible = False

# all L transferred to wheel
# neglect m of clay
omega = mag(clay.L)/I
dtheta = omega*dt
if position > 2:
    dtheta = -dtheta
theta = 0
while 1:
    rate(50)
    w.rotate(angle = dtheta, axis = (0,0,1))
    theta += dtheta