#!/usr/bin/python
"""       xturtle-example-suite:

           xtx_sierpinski.py

This program draws a coloured sierpinski
triangle.

Each vertex of the triangle is associated
with a color - in the case of this example
red, green and blue. The colors of the
triangular cells of the Sierpinski triangle
are computed by interpolation.

This interpolation uses a 3-vector class
similar to the 2-vector class, which is part
of the xturtle graphics module.
"""

from xturtle import *
from time import clock

class Vec3(tuple):

    def __new__(cls, x, y, z):
        return tuple.__new__(cls, (x, y, z))
    def __add__(self, other):
        return Vec3(self[0]+other[0], self[1]+other[1], self[2]+other[2])
    def __mul__(self, other):
        return Vec3(self[0]*other, self[1]*other, self[2]*other)
    def __rmul__(self, other):
        return Vec3(self[0]*other, self[1]*other, self[2]*other)
    def __sub__(self, other):
        return Vec3(self[0]-other[0], self[1]-other[1], self[2]-other[2])
    def __div__(self, other):
        other = float(other)
        return Vec3(self[0]/other, self[1]/other, self[2]/other)
    def __neg__(self):
        return Vec3(-self[0], -self[1], -self[2])
    def __repr__(self):
        return "(%.2f,%.2f,%.2f)" % self 


  
def triangle(laenge, stufe, f1, f2, f3):  # f1, f2, f3 colors of the vertices
    if stufe == 0:
        color((f1+f2+f3)/3)
        fill(1)
        for i in range(3):
            fd(laenge)
            lt(120)
        fill(0)
    else:
        c12 = (f1+f2)/2
        c13 = (f1+f3)/2
        c23 = (f2+f3)/2
        triangle(laenge / 2, stufe - 1, f1, c12, c13)
        fd(laenge)
        lt(120)
        triangle(laenge / 2, stufe - 1, f2, c23, c12)
        fd(laenge)
        lt(120)
        triangle(laenge / 2, stufe - 1, f3, c13, c23)
        fd(laenge)
        lt(120)

def main():
    reset()
    getpen().undobuffer.reset(1)
    sierp_size = 600
    colormode(255)
    speed(0)
    ht()
    pu()
    ##rt(90)                   ## die obligate Rechtsdrehung
    bk(sierp_size*0.5)
    lt(90)
    bk(sierp_size*0.4)
    rt(90)
    tracer(1,0)
    ## Hier nun anderen (Logo) Farbmodus nutzen:
    ta = clock()
    triangle(sierp_size, 6,
            Vec3(255.0,0,0), Vec3(0,255.0,0), Vec3(0,0,255.0))
    tb = clock()
    return "%.2f sec." % (tb-ta)

if __name__ == '__main__':
    main()
    mainloop()


## on my desktop-machine: approx. 1.5 sec.