Python Turtle Graphics - Draw Spiral Triangle

import turtle

colors = ["yellow", "blue", "red"]
c = 0
def spiral_shape(side, angle):
    global c
    if side > 0:
        t.pencolor(colors[c % 3])
        c += 1         
        t.forward(side)
        t.right(angle)
        spiral_shape(side - 5, angle)


# Window setup
window = turtle.Screen()
window.bgcolor("black")

# Turtle setup
t = turtle.Turtle()
t.shape("classic")
t.reset()
t.pen(speed=0)

# Initial condition
length = 400
turn_by = 121
t.penup()
t.setpos(-length / 2, -length / 2)
t.left(100)
t.pendown()
t.pensize(2)

# Draw
spiral_shape(length, turn_by)

window.exitonclick()

 

Spiral Triangle