Python recursive Sierpinski triangle drawing

Sierpinski triangle using the three-way recursive algorithm, starts from a large triangle, by connecting the midpoints of each side of the triangle into four triangles type, then ignores the intermediate triangle, the above-described sequentially performed for the remaining three triangles operating.

running result:

 

Source:

 1 import turtle
 2 
 3 
 4 def draw_triangle(points, color, my_angle):
 5     my_angle.fillcolor(color)
 6     my_angle.up()
 7     my_angle.goto(points[0][0], points[0][1])
 8     my_angle.down()
 9     my_angle.begin_fill()
10     my_angle.goto(points[1][0], points[1][1])
11     my_angle.goto(points[2][0], points[2][1])
12     my_angle.goto(points[0][0], points[0][1])
13     my_angle.end_fill()
14 
15 
16 def get_mid(p1, p2):
17     return ((p1[0]+p2[0])/2, (p1[1]+p2[1])/2)
18 
19 
20 def sierpinski(points, degree, my_angle):
21     colormap = ['blue', 'red', 'green', 'yellow',
22                 'violet', 'orange', 'white']
23     draw_triangle(points, colormap[degree], my_angle)
24     if degree > 0:
25         sierpinski([points[0],
26                     get_mid(points[0], points[1]),
27                     get_mid(points[0], points[2])],
28                    degree - 1, my_angle)
29         sierpinski([points[1],
30                     get_mid(points[0], points[1]),
31                     get_mid(points[1], points[2])],
32                    degree - 1, my_angle)
33         sierpinski([points[2],
34                     get_mid(points[2], points[1]),
35                     get_mid(points[0], points[2])],
36                    degree - 1, my_angle)
37 
38 
39 my_turtle = turtle.Turtle()
40 my_win = turtle.Screen()
41 my_points = [[-100, -50], [0, 100], [100, -50]]
42 sierpinski(my_points, 3, my_turtle)
43 my_win.exitonclick()