Question

我使用乌龟制作了一个随机行走程序，希望它通过更改颜色来显示两只乌龟在路径上的交叉位置。

`import turtle as T
 import random as R
 t = T.Turtle()
 u = T.Turtle()
 t.speed(0)
 u.speed(0)
 t.hideturtle()
 u.hideturtle()
 t.color("red")
 u.color("blue")
 def randWalk(num):
     for i in range(0, num):
         x = R.choice((-1,1))
         X = R.choice((-1,1))
         y = R.choice((-1,1))
         Y = R.choice((-1,1))
         t.forward(x)
         u.forward(X)
         if y == 1:
             t.left(90)
             t.forward(1)
         else:
             t.right(90)
             t.forward(1)
         if Y == 1:
             u.left(90)
             u.forward(1)
         else:
             u.right(90)
             u.forward(1)    
 randWalk(4000)`

Answer 1

Turtle无法询问屏幕上当前使用的颜色，因此一种解决方法可能是拥有某种后备存储区，您可以在其中跟踪将什么颜色写入到哪个像素中。这是一个使用Python列表的粗略示例：

from turtle import Screen, Turtle
from random import choice

WIDTH, HEIGHT = 300, 300

PEN_COLORS = ['red', 'blue']

OVERLAP_COLOR = 'green'

def randWalk(number):
    for _ in range(number):
        for turtle in turtles:
            direction = choice((-1, 1))
            turtle.forward(direction)

            x, y = map(round, turtle.position())
            old_color = color = turtle.pencolor()
            turtle.undo()  # undo forward()

            if grid[y][x] and grid[y][x] != color:
                color = OVERLAP_COLOR

            turtle.pencolor(color)
            turtle.goto(x, y)  # redo forward()
            turtle.pencolor(old_color)

            grid[y][x] = color

            choice((turtle.left, turtle.right))(90)

        screen.update()

screen = Screen()
screen.setup(WIDTH, HEIGHT)
screen.tracer(False)

grid = [[None] * WIDTH for _ in range(HEIGHT)]

turtles = []

for color in PEN_COLORS:
    turtle = Turtle()
    turtle.hideturtle()
    turtle.pencolor(color)

    turtles.append(turtle)

randWalk(4000)

screen.tracer(True)
screen.exitonclick()

随着乌龟在浮点平面上行走，代码中还会出现其他复杂情况，但是我们需要将其强制转换为整数平面，以适应我们的后备存储并减少不良的图形假象。

如何在乌龟图形中显示两条重叠的线

1 个答案: