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I am working on a game in corona. I want to fire a bullet when a user swipes their finger on an object. The further he swipes, the further the the bullet should go. I worked on this and on tap event the bullet is fired, there are two functions start projectile and game loop, start projectile is used to fire projectile and game loop is used to translate the weapon, but I can't understand how to aim for the target using finger swipe. Please give me any suggestions, thanks... Code for what has been achieved so far is below

local function startprojectile(event)     
gameIsActive=true
local firetimer
local getobj=event.target
local getxloc=getobj.x
local getyloc=getobj.y
local function firenow()
if gameIsActive=false then
timer.cancel(firetimer)
firetimer=nil
else
local bullet=display.newImageRect("object.png",50,60);
bullet.x=getxloc-50; bullet.y=getyloc-50
bullet.type=bullet1
physics.addBody(bullet,{isSensor=true})
weaponGroup:insert(bullet)
end
gameIsActive=false
end
firetimer.timer.performWithDelay(650,firenow)
end

local function gameloop()                 
local i
for i=weaponGroup.numChildren,1,-1 do
local weapon=weaponGroup[i]
if weapon ~=nil and weapon.x ~=nil
then 
weapon:translate(-20,0)
end
end
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1 回答 1

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您可以使用内置的 lua 函数获得子弹应该发射的角度

startX, startY = player.x, player.y
dir = math.atan2(( swipeY - player.y ), ( swipeX - player.x ))
bulletDx = bullet.speed * math.cos(dir)
bulletDy = bullet.speed * math.sin(dir)
table.insert( bullet, { x = startX, y = startY, dx = bulletDx, dy = bulletDy } )

您可以将变量从滑动 Y 更改为 Corona 使用的任何变量（我不使用它进行编码）。我假设你知道如何移动子弹，但如果不知道，

for i, v in ipairs( bullet ) do
    bullet.x = bullet.x + bullet.dx * dt
    bullet.y = bullet.y + bullet.dy * dt
end
于 2013-07-17T13:23:12.147 回答