from visual import *
from visual.graph import *
from random import *
rad=5e-3  # the radius of a point 

scene=display(
            title="Sierpinski triangle",
            height=600,width=600,x=0,y=200,
            foreground=color.black, background=color.white, fov=1e-8,
            userspin=0,userzoom=0, 
            center=vector(.5,.5,0),range=(0.6,0.6,0.6))

x=0.0
y=0.0

a=[0.5  , 0.5 ,  0.5   ] 
b=[0.0  , 0.0 ,  0.0   ]
c=[0.0  , 0.0 ,  0.0   ]
d=[0.5  , 0.5 ,  0.5   ]
e=[0.0  , 0.5 ,  0.25  ]
f=[0.0  , 0.0 ,  0.5   ]
K=3

#dummy needed for starting "highlighting" effect
new_point=sphere(pos=(x,y),radius=0,visible=0) 


while(1):
    rate(1500)
    dum=randint(0,K-1)
    x=a[dum]*x+b[dum]*y+e[dum]
    y=c[dum]*x+d[dum]*y+f[dum]

    #remove highlighting from the last new_point
    new_point.color=color.blue
    new_point.radius=rad
    #now, show a new point with highlighting
    new_point=sphere(pos=(x,y),radius=5.*rad,color=color.red)