python - 如何将三角形堆叠在一起并增加大小并完美对齐

Question

我正在玩 Python，我想将 4 个三角形堆叠在一起，但大小增加，每个三角形的顶部应该正好位于上面三角形基线的一半。下面是我正在使用的代码，但上面的三角形不断向左移动，我不知道如何将它保持在中心位置。

# Draw 4 triangles increasing in size
from turtle import *

# Draw a triangle
for sides in range (1,4):
    forward(20)
    left(120)

# Move to position for second triangle
penup()
left(120)
forward(20)
right(120)
pendown()

# Draw second triangle
for sides in range (1,4):
    forward(40)
    left(120)

# Move to position for third triangle
penup()
left(120)
forward(40)
right(120)
pendown()

# Draw third triangle
for sides in range (1,4):
    forward(60)
    left(120)

# Move to position for fourth triangle
penup()
left(120)
forward(60)
right(120)
pendown()

# Draw fourth triangle
for sides in range (1,4):
    forward(80)
    left(120)

Answer 1

您需要调整计算每个三角形起点的方式。
您当前的方法仅适用于尺寸翻倍的直角三角形。
简单的方法是将您的步骤退回到刚刚绘制的三角形的顶点，向左转 120 度，然后向前移动下一个三角形距离的一半。
修改您的代码以执行此操作将如下所示。

# Draw 4 triangles increasing in size
from turtle import *

# Draw a triangle
for sides in range (1,4):
    forward(20)
    left(120)

# Move to position for second triangle
penup()
# point left towards the apex
left(60)
# move to the apex
forward(20)
# turn left in order to move horizontally
left(120)
# move along the next base half the distance of the next triangle(center it)
forward(20)
# turn back around in order to start drawing the next triangle
left(180)
pendown()

# Draw second triangle
for sides in range (1,4):
    forward(40)
    left(120)

# Move to position for third triangle
penup()
left(60)
forward(40)
left(120)
forward(30)
right(180)
pendown()

# Draw third triangle
for sides in range (1,4):
    forward(60)
    left(120)

# Move to position for fourth triangle
penup()
left(60)
forward(60)
left(120)
forward(40)
right(180)
pendown()

# Draw fourth triangle
for sides in range (1,4):
    forward(80)
    left(120)

但是，这里有很多重复的代码。通过将可重复的部分放在函数中并使用循环，您可以将其压缩很多。

# Draw 4 triangles increasing in size
from turtle import *

def draw_triangle(size):
    for _ in range(3):
        forward(size)
        left(120)

def move_to_next_position(previous_size, next_size):
    penup()
    left(60)
    forward(previous_size)
    left(120)
    forward(next_size // 2)
    left(180)
    pendown()

draw_triangle(20)
for prev, nxt in zip((20, 40, 60), (40, 60, 80)):
    move_to_next_position(prev, nxt)
    draw_triangle(nxt)