我想创建SpaceInvaders游戏，但它不会朝敌人射击，而是朝玩家射击。我使用.goto()这样的方法来实现它：
bullet2.goto(player.xcor(),player.ycor())
但是这里的问题是子弹根据玩家的坐标固定了它的目的地，因此卡在了那里。我希望他们继续朝这个方向移动，直到敌人再次射击后才进入屏幕（我没有找到直接的方法来计算两个海龟位置之间的航向）。
我也很难确定将
bullet2.goto(player.xcor(),player.ycor())命令放在哪里：它应该在while(True)的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2种不同类型的敌人，一个绕圈移动，而另一个则以方形移动。第一个敌人进行4步射击后开火，第二个敌人进行2步射击后开火。他们发射的所有东西，子弹都向玩家移动，除非子弹离开屏幕，否则敌人将无法再次发射。
我不是在寻找碰撞。
我知道在使所有内容都面向对象方面可以改进很多，但是现在我专注于游戏的功能。一旦我清除了基本功能，便会执行此操作。
# 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. > ")
答案 0 :(得分：1)
如果您仍然有兴趣解决此问题，则应解决直角三角形（见图）：
px
---------|--x--------|
| | | |
| | x |
y--------|-[e]y------y
| |/ | |
py-------*py--------py
| /px | |
| / | | |
| / | | |
| / | | |
|---v----|--x--------|
y2=-280
x2=?
让[e]为敌人，*为玩家，x和y为敌人的坐标，px和py是玩家的坐标。对于所示情况，您应该从以下关系中获得x2坐标：
(x-px)/(y-py) = (x-x2)/(y-(-280)) => (x-x2) = (y-(-280))*(x-px)/(y-py) =>
=> x2 = x-(y-(-280))*(x-px)/(y-py)，
已知x，y，px，py和y2。
并且您必须考虑玩家和敌人的相对位置，例如：
px
---------|------x----|
| | | |
| | | |
| | x |
y--------|-- . [e]y--y
py-------*py----|---py
| . px | |
| . | | |
y2=? <. ------|------|----|
x2=-280| | | |
|--------|------x----|
(x-px)/(y-py) = (x-(-280))/(y-y2) => (y-y2) = (x-(-280))*(y-py)/(x-px) =>
=> y2 = y-(x-(-280))*(y-py)/(x-px)，
以及坐标差异的符号。
在您的情况下，这会将我们引至以下代码（我建议您将其设计为单独的函数）：
MAX_COOR=330
def bullet_calc(player,x,y):
diff_x=x-player.xcor()
diff_y=y-player.ycor()
if diff_y==0:
goal_y=y
if diff_x>0:
goal_x=-MAX_COOR
elif diff_x<=0:
goal_x=MAX_COOR
elif diff_x==0:
goal_x=x
if diff_y>0:
goal_y=-MAX_COOR
elif diff_y<=0:
goal_y=MAX_COOR
elif diff_x>0 and diff_y>0 and abs(diff_x)<abs(diff_y): # |- - enemy
goal_x=x-(y-(-MAX_COOR))*diff_x/diff_y # ---*--- * player
goal_y=-MAX_COOR # |
elif diff_x>0 and diff_y>0 and abs(diff_x)>abs(diff_y): # | _
goal_x=-MAX_COOR # ---*---
goal_y=y-(x-(-MAX_COOR))*diff_y/diff_x # |
elif diff_x<0 and diff_y>0 and abs(diff_x)<abs(diff_y): # -|
goal_x=(y-MAX_COOR)*diff_x/diff_y-x # ---*---
goal_y=-MAX_COOR # |
elif diff_x<0 and diff_y>0 and abs(diff_x)>abs(diff_y): # _ |
goal_x=MAX_COOR # ---*---
goal_y=(x-(-MAX_COOR))*diff_y/diff_x-y # |
elif diff_x>0 and diff_y<0 and abs(diff_x)<abs(diff_y): # |
goal_x=(y-(-MAX_COOR))*diff_x/diff_y-x # ---*---
goal_y=MAX_COOR # |_
elif diff_x>0 and diff_y<0 and abs(diff_x)>abs(diff_y): # |
goal_x=-MAX_COOR # ---*--_
goal_y=(x-MAX_COOR)*diff_y/diff_x-y # |
elif diff_x<0 and diff_y<0 and abs(diff_x)<abs(diff_y): # |
goal_x=x-(y-MAX_COOR)*diff_x/diff_y # ---*---
goal_y=MAX_COOR # _|
elif diff_x<0 and diff_y<0 and abs(diff_x)>abs(diff_y): # |
goal_x=MAX_COOR # _--*---
goal_y=y-(x-MAX_COOR)*diff_y/diff_x # |
return (goal_x,goal_y)
在触发项目符号的函数中调用此代码似乎更容易：
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"
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.showturtle() # move <showturtle()> here
bullet1.goto(bullet_calc(player,x,y))
#bullet1.goto(player.xcor(), player.ycor()) # your old code
如果玩家位于场地中央，所有这些操作将变得更加容易。
答案 1 :(得分：0)
代替：
if bulletstate1=="fired":
bullet1.goto(player.xcor(),player.ycor())
你想要的是什么
if bulletstate1 == 'fired':
bullet1.setheading(bullet1.towards(player))
bullet1.forward(min(10, bullet1.distance(player))
那是在您的运动循环中，在每次迭代中，将子弹转向玩家的当前位置并略微向前移动。如果玩家静止不动，子弹最终将击中他们。如果玩家正在移动，子弹将对其进行追踪。
但是，子弹不可能“离开屏幕” 。如果前进幅度很大
bullet1.forward(min(100, bullet1.distance(player))