from visual import *
from random import random
# A corner is a point in 3D, so a 3-tuple like this:  (x, y, z)

def halfway_between(p1, p2):
    x1, y1, z1 = p1
    x2, y2, z2 = p2
    def avg(a, b):
        return (a + b) / 2.0
    return (avg(x1, x2), avg(y1, y2), avg(z1, z2))

def draw_mesh(corners, divs_left):
    c1, c2, c3, c4 = corners
    c1 = (c1[0], c1[2], random() * 3)
    c2 = (c2[0], c2[2], random() * 3)
    c3 = (c3[0], c3[2], random() * 3)
    c4 = (c4[0], c4[2], random() * 3)


    # Base case:  No more divs left!
    if not divs_left:
        print("Drawing curve:  ", corners)
        curve(pos=[c1, c2, c3, c4, c1], radius=0.5)
        sphere(pos=c1)
        sphere(pos=c2)
        sphere(pos=c3)
        sphere(pos=c4)
        return
    # General case:  We have some divs left
    s12 = halfway_between(c1, c2)
    s23 = halfway_between(c2, c3)
    s34 = halfway_between(c3, c4)
    s41 = halfway_between(c4, c1)
    cent = halfway_between(c4, c2)
    draw_mesh((c1, s12, cent, s41), divs_left-1)
    draw_mesh((s12, c2, s23, cent), divs_left-1)
    draw_mesh((cent, s23, c3, s34), divs_left-1)
    draw_mesh((s41, cent, s34, c4), divs_left-1)

draw_mesh([(10, 10, -5), (10, -10, 5), (-10, -10, -5), (-10, 10, 5)], 3)