python - 如何让一只 turtle 向另一只 turtle 的位置移动？

Question

我想创建 SpaceInvaders 游戏，但敌人不会被击落，而是会向玩家射击。我使用 .goto() 方法实现它，如下所示:

bullet2.goto(player.xcor(),player.ycor())

但这里的问题是，子弹根据玩家的坐标确定了目的地，从而卡在那里。我希望它们继续朝那个方向移动，直到敌人可以再次射击后它离开屏幕(我没有找到计算两个 turtle 位置之间的航向的直接方法)。

我也无法弄清楚将 放在哪里 Bullet2.goto(player.xcor(),player.ycor())命令:它应该在while(True)循环中或在发射子弹的函数中。

我在下面发布我的代码。我的目标是:有两种不同类型的敌人，一种以圆圈移动，另一种以方形图案移动。第一个敌人在移动 4 次后开火，第二个敌人在移动 2 次后开火。他们发射的所有子弹都会朝玩家移动，除非子弹离开屏幕，否则敌人无法再次射击。

我不是在寻找碰撞。

我知道在使一切都面向对象方面可以改进很多，但现在我专注于游戏的功能。一旦我清除了基本功能就会这样做。

# python 2.7 and turtle library

import os
import random
import sys
import turtle
turtle.fd(0)
turtle.speed(6)
turtle.bgcolor("black")
turtle.ht()
turtle.setundobuffer(1)
turtle.tracer(1)

class Game():       
    def draw_border(self):
        #Draw border
        self.pen = turtle.Turtle()
        self.pen.speed(0)
        self.pen.color("white")
        self.pen.pensize(3)
        self.pen.penup()
        self.pen.goto(-300, 300)
        self.pen.pendown()
        for side in range(4):
            self.pen.fd(600)
            self.pen.rt(90)
        self.pen.penup()
        self.pen.ht()

game = Game()
game.draw_border()

bulletstate1 = "ready"
bulletstate2 = "ready"

def enemy1_fire():
    #the bullet will travel up from the player's position
    global bulletstate1 # enable modifying global var from inside of function
    if bulletstate1 == "ready":
        bulletstate1 = "fired"
        bullet1.showturtle()
        x = enemy1.xcor() # get the coordinates at the time of firing
        y = enemy1.ycor()
        bullet1.speed = 6
        bullet1.setposition(x,y) # bullet will appear just above the player
        #bullet1.goto(player.xcor(),player.ycor())
        #print(bulletspeed,bullet.xcor(),bullet.ycor(),bulletstate1)

def enemy2_fire():
    #the bullet will travel up from the player's position
    global bulletstate2 # enable modifying global var from inside of function
    if bulletstate2 == "ready":
        bulletstate2 = "fired"
        bullet2.showturtle()
        x = enemy2.xcor()
        y = enemy2.ycor()
        bullet2.speed = 6
        bullet2.setposition(x,y) # bullet will appear just above the player
        #bullet2.goto(player.xcor(),player.ycor())
        #print(bulletspeed,bullet.xcor(),bullet.ycor(),bulletstate2)

class Player(turtle.Turtle):
    def __init__(self, spriteshape, color, startx, starty):
        turtle.Turtle.__init__(self, shape = spriteshape)
        self.speed(3)
        self.penup()
        self.color(color)
        self.fd(0)
        self.goto(startx, starty)
        self.speed = 1
        self.left(90)
        #self.mode("logo")  

    def move(self):
        self.fd(self.speed)
        if (player.xcor()<-280): # boundary checking
            player.setx(-280)
        if (player.xcor()> 280): # boundary checking
            player.setx(280)
        if (player.ycor()<-280): # boundary checking
            player.sety(-280)
        if (player.ycor()> 280): # boundary checking
            player.sety(280)

    def turn_left(self):
        self.move()
        self.lt(30)
        if (player.xcor()<-280): # boundary checking
            player.setx(-280)
        if (player.xcor()> 280): # boundary checking
            player.setx(280)
        if (player.ycor()<-280): # boundary checking
            player.sety(-280)
        if (player.ycor()> 280): # boundary checking
            player.sety(280)

    def turn_right(self):
        self.move()
        self.rt(30)
        if (player.xcor()<-280): # boundary checking
            player.setx(-280)
        if (player.xcor()> 280): # boundary checking
            player.setx(280)
        if (player.ycor()<-280): # boundary checking
            player.sety(-280)
        if (player.ycor()> 280): # boundary checking
            player.sety(280)

    def accelerate(self):
        self.move()
        self.speed = self.speed + 1
        if (player.xcor()<-280): # boundary checking
            player.setx(-280)
        if (player.xcor()> 280): # boundary checking
            player.setx(280)
        if (player.ycor()<-280): # boundary checking
            player.sety(-280)
        if (player.ycor()> 280): # boundary checking
            player.sety(280)

    def brake(self):
        self.speed = self.speed - 1
        if (player.xcor()<-280): # boundary checking
            player.setx(-280)
        if (player.xcor()> 280): # boundary checking
            player.setx(280)
        if (player.ycor()<-280): # boundary checking
            player.sety(-280)
        if (player.ycor()> 280): # boundary checking
            player.sety(280)

class Enemy1(turtle.Turtle):
    def __init__(self, spriteshape, color, startx, starty):
        turtle.Turtle.__init__(self, shape = spriteshape)
        self.speed(3) #animation speed
        self.penup()
        self.color(color)
        self.fd(0)
        self.goto(startx, starty)
        self.speed = 1
        #self.mode("logo")

    shoot = 4 # shoots after 4 interval

    def move(self):
        self.lt(90)
        self.fd(150)
        self.shoot = self.shoot - 1
        if self.shoot==0:
            enemy1_fire() #shoot below, better if can be directed at player
            self.shoot = 4

class Enemy2(turtle.Turtle):
    def __init__(self, spriteshape, color, startx, starty):
        turtle.Turtle.__init__(self, shape = spriteshape)
        self.speed(3)
        self.penup()
        self.color(color)
        self.fd(0)
        self.goto(startx, starty)
        self.speed = 1
        #self.mode("logo")

    shoot = 2 # shoots after 2 interval

    def move(self):
        self.fd(100)
        self.rt(30)
        self.shoot= self.shoot-1
        if self.shoot==0:
            enemy2_fire() #shoot towards player
            self.shoot = 2

enemy1 = Enemy1("circle", "red", 50, -50)
enemy2 = Enemy2("square", "blue", -10, 200)
player = Player("triangle", "white", 0, 0)


#key bindings
turtle.listen()
turtle.onkey(player.turn_left,"Left")
turtle.onkey(player.turn_right,"Right")
turtle.onkey(player.accelerate,"Up")
turtle.onkey(player.brake,"Down")

# create a bullet for the enemy1
bullet1  = turtle.Turtle()
bullet1.color("yellow")
bullet1.shape("triangle")
bullet1.penup()
bullet1.shapesize(0.3,0.3) # length and breadth of bullet
bullet1.hideturtle()
bullet1.speed(3)
bullet1.speed = 2

# create a bullet for the enemy2
bullet2  = turtle.Turtle()
bullet2.color("yellow")
bullet2.shape("square")
bullet2.penup()
bullet2.shapesize(0.4,0.4) # length and breadth of bullet
bullet2.hideturtle()
bullet2.speed(3)
bullet2.speed = 2


while True:
    enemy1.move()
    enemy2.move()

    if bulletstate1=="fired":
        # y = bullet1.ycor()
        # y = y - bullet1.speed
        # bullet1.sety(y)
        bullet1.goto(player.xcor(),player.ycor())

    if bulletstate2=="fired":
        # y = bullet2.ycor()
        # y = y - bullet2.speed
        # bullet2.sety(y)
        bullet2.goto(player.xcor(),player.ycor())

    if (bullet1.ycor()>275 or bullet1.xcor()>275 or bullet1.ycor()<-275 or bullet1.xcor()<-275):
        bullet1.hideturtle()
        # bullet1.sety(enemy1.ycor)
        # bullet1.setx(enemy1.xcor)
        bulletstate1="ready"


    if (bullet2.ycor()>275 or bullet2.xcor()>275 or bullet2.ycor()<-275 or bullet2.xcor()<-275):
        bullet2.hideturtle()
        # bullet2.sety(enemy2.ycor)
        # bullet2.setx(enemy2.xcor)
        bulletstate2="ready"

sys.stdout.close()
delay = raw_input("Press enter to finish. > ")

Answer 1

而不是这样做:

if bulletstate1=="fired":
    bullet1.goto(player.xcor(),player.ycor())

你想要的是:

if bulletstate1 == 'fired':
    bullet1.setheading(bullet1.towards(player))
    bullet1.forward(min(10, bullet1.distance(player))

这是在你的运动循环中，在每次迭代中让子弹转向玩家当前的位置并稍微向前移动。如果玩家站着不动，子弹最终会击中他们。如果玩家在移动，子弹就会跟踪他们。

但是，子弹不太可能“离开屏幕”。可能如果前进的步伐非常大:

 bullet1.forward(min(100, bullet1.distance(player))