如何在python中创建雪花时使用if和then语句

Question

- 我是初学者..所以我不确定如何确保雪花不会重叠。谢谢！

import turtle

turtle.right(90)

turtle.penup()

turtle.goto(-700,300)

turtle.pendown()

def snowflakebranch(n):

    turtle.forward(n*4)
    for i in range(3):
        turtle.backward(n)
        turtle.right(45)
        turtle.forward(n)
        turtle.backward(n)
        turtle.left(90)
        turtle.forward(n)
        turtle.backward(n)
        turtle.right(45)

def snowflake(n):

    for i in range(8):
        snowflakebranch(n)
        turtle.backward(n)
        turtle.right(45)

import random

turtle.colormode(255)

turtle.tracer(0)

for i in range(35):

    r = random.randint(0, 255)
    g = random.randint(0, 255)
    b = random.randint(0, 255)
    turtle.color(r, g, b)
    x = random.randint(-500, 500)
    y = random.randint(-500, 500)
    d = random.randint(6, 16)
    snowflake(d)
    turtle.penup()
    turtle.goto(x, y)
    #turtle.forward(250)
    turtle.pendown()


    turtle.update()

Answer 1

一种方法是计算每个雪花的边界矩形（或圆）。将它们保存为列表或集合。无论何时计划制作新的雪花，首先要检查其边界矩形（或圆形）是否与之前任何雪花的边界重叠。如果是，请不要绘制它。如果没有，请绘制它并保存其边界。这种方法的概述不完整：

import turtle
import random

def snowflakebranch(n):

    turtle.forward(n * 4)

    for _ in range(3):
        turtle.backward(n)
        turtle.right(45)
        turtle.forward(n)
        turtle.backward(n)
        turtle.left(90)
        turtle.forward(n)
        turtle.backward(n)
        turtle.right(45)

def snowflake(n):

    for _ in range(8):
        snowflakebranch(n)
        turtle.backward(n)
        turtle.right(45)

def overlapping(bounds_list, bounds):
    for previous in bounds_list:
        if overlap(previous, bounds):
            return True

    return False

def overlap(b1, b2):
    # return True or False if these two rectanges or circles overlap
    pass

turtle.penup()

turtle.colormode(255)

turtle.tracer(0)

previous_bounds = []

i = 0

while i < 35:

    x = random.randint(-500, 500)
    y = random.randint(-500, 500)
    turtle.goto(x, y)

    r = random.randint(0, 255)
    g = random.randint(0, 255)
    b = random.randint(0, 255)
    turtle.color(r, g, b)

    turtle.pendown()

    d = random.randint(6, 16)

    # work out the bounding rectangle or circle based on 'd', 'x' & 'y'
    # e.g. (x, y, width & height) or (x, y, radius)
    bounds = ( ... )  

    if not overlapping(previous_bounds, bounds):

        snowflake(d)

        turtle.update()

        previous_bounds.append(bounds)

        i += 1

    turtle.penup()

turtle.done()

使用上述逻辑和边界圆圈显示非重叠雪花的图像：

我其实喜欢你重叠雪花的样子。即使你想要重叠，上面的逻辑也可以让你控制多少重叠。