Question

问题在于函数名称＆＃34; bullet Collision）碰撞后我无法移除子弹。如果删除行self：removeSelf（），则运行代码。这个错误显示在子弹与敌人发生碰撞之后。

--Physics world creation

local physics = require ("physics")
physics.start()
physics.setGravity(1,1)

--screen
local width=display.contentWidth
local height=display.contentHeight

--game characters
local enemy
local hero
local bullet
local background
local score
local counter

--backGround
background= display.newImage("night_sky.png",width/2,height/2,true)


--collision filters
local heroCollisionFilter = { categoryBits=1, maskBits=2 }
local enemyCollisionFilter = { categoryBits=2, maskBits=7 }
local bulletCollisionFilter = { categoryBits=4, maskBits=2 }




--hero's death
function heroCollision(event)
end

--bullet heat
function bulletCollision(event, self)
    print("bullet collided")
    if event.other.name == "enemy" then
        self:removeSelf()
        event.other:removeSelf()
        event.other= nil

    end


end





--fire
function fireBullet(event)
    bullet=display.newImage("bullet.png",hero.x,hero.y )
    physics.addBody(bullet,{filter=bulletCollisionFilter})
    bullet.name=bullet
    local gx = event.x-bullet.x
    local gy = event.y-bullet.y
    physics.setGravity(gx/10,gy/10)
    bullet.collision= bulletCollision
    bullet:addEventListener("collision", bulletCollision)

end


function addEnemy()

    local enemy = display.newImage("ball.png",40,50)
    physics.addBody(enemy,{filter=enemyCollisionFilter})
    enemy.gravityScale=0
    enemy:addEventListener("tap",fireBullet)
    enemy.name= "enemy"
end

addEnemy()




background:addEventListener("tap", fireBullet)

hero = display.newImage("pearl1.png",width/2,height/2,true)

Answer 1

您没有正确设置碰撞。

bullet.collision已正确设置为碰撞函数bulletCollision，但您没有正确设置事件侦听器。您应该bullet:addEventListener("collision", bullet)而不是bullet:addEventListener("collision", bulletCollision)。
“collision”事件的事件侦听器函数具有切换的参数顺序。它应该是(self, event)，而不是(event, self)

全部根据the collision documentation。

function bulletCollision(self, event)
    print("bullet collided")
    if event.other.name == "enemy" then
        self:removeSelf()
        event.other:removeSelf()
        event.other= nil
    end
end

function fireBullet(event)
    bullet=display.newImage("bullet.png",hero.x,hero.y )
    physics.addBody(bullet,{filter=bulletCollisionFilter})
    bullet.name=bullet
    local gx = event.x-bullet.x
    local gy = event.y-bullet.y
    physics.setGravity(gx/10,gy/10)
    bullet.collision= bulletCollision
    bullet:addEventListener("collision", bullet)
end

Answer 2

每次删除之前，您需要检查显示对象是否为空，如：

if xxx ~= nil then
    xxx:removeSelf()
    xxx = nil
end

lua programming.attempt索引本地＆＃39; self＆＃39; （零值），堆栈追溯：

2 个答案: