#ShowTriPartition.py
""" Illustrates the recursive procedure Partition.
This procedure ``tiles'' a given triangle with
smaller triangles.
"""
from simpleGraphicsE import *

def Partition(x,y,L):
    """ Draws a level L partitioning of the
    triangle whose vertices are defined by x and y.
    
    PreCond: x and y are length-3 lists of numbers and L is a nonnegative int.
    """
    map(float,x)
    map(float,y)
    if L==0:
        DrawPoly(x,y,color=YELLOW)
    else:
        # Compute the midpoint coordinates.
        a = [(x[0]+x[1])/2,(x[1]+x[2])/2,(x[2]+x[0])/2]
        b = [(y[0]+y[1])/2,(y[1]+y[2])/2,(y[2]+y[0])/2]
        # Paint the inner triangle
        DrawPoly(a,b,color=MAGENTA)
        # Partition each of the corner triangles
        Partition([x[0],a[0],a[2]],[y[0],b[0],b[2]],L-1)
        Partition([x[1],a[0],a[1]],[y[1],b[0],b[1]],L-1)
        Partition([x[2],a[1],a[2]],[y[2],b[1],b[2]],L-1)
        
if __name__ == '__main__':
    x = [-5.,5.,3.]
    y = [-5.5,-5.,5.]
    # Display level-0, level-1, level-2, level-3, and level-4 partitionings
    # of the same triangle

    MakeWindow(6,bgcolor=WHITE,labels=False)
    Partition(x,y,0)
    MakeWindow(6,bgcolor=WHITE,labels=False)
    Partition(x,y,1)
    MakeWindow(6,bgcolor=BLACK,labels=False)
    Partition(x,y,2)
    MakeWindow(6,bgcolor=BLACK,labels=False)
    Partition(x,y,3)
    MakeWindow(6,bgcolor=BLACK,labels=False)
    Partition(x,y,4)
    ShowWindow()