from gpanel import *
from math import sin,cos,pi

R=1
r=1
points = []

def v1(a):
    return [(R+r)*cos(a),(R+r)*sin(a)]
def v2(a):
    b = a * R/r - pi + a
    return [r*cos(b),r*sin(b)]
def add(v1,v2):
    return [v1[0]+v2[0],v1[1]+v2[1]]

makeGPanel(-4,4,-4,4)

t=0
dt=0.0025
while t<=2*pi:
    p1=v1(t)
    p2=v2(t)
    p3=add(p1,p2)
    points.append(p3)
    move(0,0)
    setColor("black")
    delay(2)
    
    clear()
    
    circle(R)
    move(p1)
    circle(r)
    setColor("red")
    move(p3)
    fillCircle(0.1)
    for p in points:
        point(p)
    t=t+dt