将 SKSpriteNode 移动到触摸的位置

Question

以上是我的游戏图片。自上而下的游戏。无论玩家触摸屏幕上的哪个位置，我都希望子弹在一段时间内到达那个位置。我还希望玩家能够在屏幕上拖动手指，同样的事情也会发生。这样玩家就不用每次想射击都去触摸屏幕了。

到目前为止，我已经尝试了一些不同的东西，但似乎没有任何效果。

首先，我不知道我是否应该为子弹设置一个单独的功能。但无论如何，这是我的子弹功能。

func spawnBullets() {
    let bullet = SKSpriteNode(imageNamed: "Bullet")
    bullet.name = "Bullet"
    bullet.zPosition = 4
    bullet.position = CGPoint(x: player.position.x + 19, y: 
    player.position.y)
    self.addChild(bullet)
}

在 didMove 函数中我还有一个用于子弹的“计时器”：

var timer = Timer.scheduledTimer(timeInterval: 0.1, target: self, 
selector: Selector("spawnBullets"), userInfo: nil, repeats: true)

最后，这是我的 touchesBegan 函数：

override func touchesBegan(_ touches: Set<UITouch>, with event: 
UIEvent?) {        
    for  touch in touches {            
        let location = touch.location(in: self)            
        let moveToPoint = SKAction.move(to: location, duration: 0.5)
        let repeatAction = SKAction.repeatForever(moveToPoint)            
        bullet.run(moveToPoint)
    }

}

Answer 1

你来了 - 一个简单的应用程序，其中包含可以在屏幕上拖动的飞船和向触摸位置发射的导弹。

如果你触摸船，你可以拖动它；在船外触摸，导弹会从飞船发射到触摸位置。

import SpriteKit

class GameScene: SKScene {

var ship = SKSpriteNode()
var shipIsTouched = false
var missileDestination = CGPoint()
let missileSpeed: CGFloat = 800 // Points per second)
let missileFireRate : TimeInterval = 0.2 // Seconds between each missile

override func didMove(to view: SKView) {
    missileDestination = CGPoint(x: 0, y: (self.size.height / 2))
    createPlayerShip()
    let fire = SKAction.sequence([SKAction.run(fireMissile), SKAction.wait(forDuration: missileFireRate)])
    run(SKAction.repeatForever(fire))
}

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    if let touch = touches.first {
        if ship.contains(touch.location(in: self)) {
            shipIsTouched = true
        } else {
            missileDestination = touch.location(in: self)
            ship.zRotation = direction(to: missileDestination, from: ship.position) - CGFloat(Double.pi/2)
        }
    }
}

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    if (shipIsTouched == true) {
        ship.position = (touches.first?.location(in: self))!
        ship.zRotation = direction(to: missileDestination, from: ship.position) - CGFloat(Double.pi/2)
    }
}

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
    if shipIsTouched {
        shipIsTouched = false
    }
}

override func update(_ currentTime: TimeInterval) {
    // Called before each frame is rendered
}

func createPlayerShip() {
    ship = SKSpriteNode(imageNamed: "Spaceship")
    ship.zRotation = CGFloat(-Double.pi/2.0)
    ship.scale(to: CGSize(width: 150, height: 150))
    ship.position = CGPoint(x: -size.width/2 + 200, y: 0)

    addChild(ship)
}


func fireMissile() {
    let missile = SKSpriteNode(color: .white, size: CGSize(width: 50, height: 10))
    missile.position = ship.position

    let missileFlightTime = travelTime(to: missileDestination, from: ship.position, atSpeed: missileSpeed)
    missile.zRotation = direction(to: missileDestination, from: missile.position)

    addChild(missile)

    let missileMove = SKAction.move(to: missileDestination,
                                    duration: TimeInterval(missileFlightTime))
    let missileRemove = SKAction.removeFromParent()
    missile.run(SKAction.sequence([missileMove, missileRemove]))
}

func travelTime(to target : CGPoint, from : CGPoint, atSpeed speed : CGFloat) -> TimeInterval {
    let distance = sqrt(pow(abs(target.x - from.x),2) +
        pow(abs(target.y - from.y),2))
    return TimeInterval(distance/speed)
}


func direction(to target : CGPoint, from: CGPoint) -> CGFloat {
    let x = target.x - from.x
    let y = target.y - from.y
    var angle = atan(y / x)
    if x < 0 {
        angle = angle + CGFloat.pi
    }
    return angle
}
}

有一些额外的技巧可以让导弹的速度保持一致（因为 moveTo 需要时间，而不是速度，所以如果目的地很近，导弹会缓慢移动，如果更远，它们会移动得更快）并且使导弹旋转以朝向目的地。

您可以为导弹创建一条弯曲的路径以跟随到目的地，这看起来很酷，但可能不适合您的应用。

编辑：

如果您希望飞船静止，导弹跟随您的手指，请将所有代码替换为 createPlayerShip （是的，我们丢失了 touchesEnded() 和 update()：

import SpriteKit

class GameScene: SKScene {

var ship = SKSpriteNode()
var missileDestination = CGPoint()
let missileSpeed: CGFloat = 800 // Points per second)
let missileFireRate : TimeInterval = 0.2 // Seconds between each missile

override func didMove(to view: SKView) {
    missileDestination = CGPoint(x: size.height/2, y: 0)
    createPlayerShip()
    let fire = SKAction.sequence([SKAction.run(fireMissile), SKAction.wait(forDuration: missileFireRate)])
    run(SKAction.repeatForever(fire))
}

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    if let touch = touches.first {
            missileDestination = touch.location(in: self)
    }
}

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        missileDestination = (touches.first?.location(in: self))!
}