# draws an impossible tribar
#
# style of Oscar Reutersvärd, 1934
# Wolfgang.Urban@schule.at

NOT_IN_IDLE = 1

from Tkinter import *
from math import *

# draw a full cube 
class Cube:
    def __init__(self,parent,x,y,s):
        dx,dy = s/2.0*sqrt(3.0),s/2.0
        parent.create_polygon(x-dx,y-dy,x,y,x+dx,y-dy,x,y-s,x-dx,y-dy,
                              fill="#30e030",outline="#000000",width=4)
        parent.create_polygon(x-dx,y-dy,x,y,x,y+s,x-dx,y+dy,x-dx,y-dy,
                              fill="#e08080",outline="#000000",width=4)
        parent.create_polygon(x+dx,y-dy,x,y,x,y+s,x+dx,y+dy,x+dx,y-dy,
                              fill="#b0b0ff",outline="#000000",width=4)

# only left and top
class Cube_Part:
    def __init__(self,parent,x,y,s):
        dx,dy = s/2.0*sqrt(3.0),s/2.0
        parent.create_polygon(x-dx,y-dy,x,y,x+dx,y-dy,x,y-s,x-dx,y-dy,
                              fill="#30e030",outline="#000000",width=4)
        parent.create_polygon(x-dx,y-dy,x,y,x,y+s,x-dx,y+dy,x-dx,y-dy,
                              fill="#e08080",outline="#000000",width=4)
        


class CanvasFrame(Frame):

    def __init__(self,parent,sizex,sizey,use_trick):
        Frame.__init__(self,parent,border=2,relief=RIDGE)
        self.cv = Canvas(self,width=sizex,height=sizey,bg="#ffffff")
        self.cv.pack()
        self.pack()
        self.update()
        
        s = sizey/7.2
        dvy = s*3.0/2.0
        dx = 3.0/4*s*sqrt(3)
        dy = 3.0*s/4

        x,y = 105,105

        Cube(self.cv,x+1*dx,y+1*dy,s)
        Cube(self.cv,x+2*dx,y+2*dy,s)
        Cube(self.cv,x+3*dx,y+3*dy,s)
        Cube(self.cv,x+2*dx,y+4*dy,s)
        Cube(self.cv,x+1*dx,y+5*dy,s)
        Cube(self.cv,x+0*dx,y+6*dy,s)
        Cube(self.cv,x+0*dx,y+2*dvy,s)
        Cube(self.cv,x+0*dx,y+1*dvy,s)
        Cube(self.cv,x+0*dx,y+0*dvy,s)

        if use_trick: Cube_Part(self.cv,x+1*dx,y+1*dy,s)
        
        if NOT_IN_IDLE: self.mainloop()

class TriBar:

    def __init__(self,use_trick=1):
        self.root = Tk()
        self.root.title("The Tribar")
        self.cf = CanvasFrame(self.root,520,580,use_trick)
        self.cf.pack()
        
d = TriBar(1)           # (0) gives real tribar