经典分形示例 15.4

# 科赫雪花
def koch_curve(length, depth):
    """绘制科赫曲线"""
    if depth == 0:
        t.forward(length)
    else:
        koch_curve(length/3, depth-1)
        t.left(60)
        koch_curve(length/3, depth-1)
        t.right(120)
        koch_curve(length/3, depth-1)
        t.left(60)
        koch_curve(length/3, depth-1)

def koch_snowflake(length, depth):
    """绘制科赫雪花"""
    t.penup()
    t.goto(-length/2, length/3)
    t.pendown()
    
    for i in range(3):
        koch_curve(length, depth)
        t.right(120)

# 绘制科赫雪花
t.clear()
t.pencolor("lightblue")
koch_snowflake(200, 3)

# 科赫雪花
def koch_curve(length, depth):
    """绘制科赫曲线"""
    if depth == 0:
        t.forward(length)
    else:
        koch_curve(length/3, depth-1)
        t.left(60)
        koch_curve(length/3, depth-1)
        t.right(120)
        koch_curve(length/3, depth-1)
        t.left(60)
        koch_curve(length/3, depth-1)

def koch_snowflake(length, depth):
    """绘制科赫雪花"""
    t.penup()
    t.goto(-length/2, length/3)
    t.pendown()
    
    for i in range(3):
        koch_curve(length, depth)
        t.right(120)

# 绘制科赫雪花
t.clear()
t.pencolor("lightblue")
koch_snowflake(200, 3)