如何抛出 SKSpriteNode？

Question

所以基本上在我的游戏中我需要扔东西。到目前为止，我有一个精灵，它可以拖动但不能扔。游戏的想法是抛出一个精灵与另一个精灵碰撞。我想要我们称之为 testNode 的精灵，移动用户扔它的位置

意思是，当我释放精灵时，我希望它继续朝着我移动它的方向前进。我花了很长时间试图解决这个问题，但我做不到。我正在为 iOS 8+ 使用 SpriteKit。如果有人可以帮忙，请做。

我看到了一个视频，但它是与 GameSalad 相关的，这是另一个故事。你可以看看

https://www.youtube.com/watch?v=nn3lWa5jUGE

（如果您可能需要进一步联系，请回复）

import Foundation;
import SpriteKit;

class Level:SKScene {

TestNode:Test? //Test is a class I made

//Removed the update and touches began due to it being irrelevant to what I need help with. 

  override func didMoveToView(view: SKView){
    testNode = Fruit(imageNamed: "apple_idle")
    testNode?.position = CGPointMake(60, 294)
    testNode?.xScale = 0.5
    testNode?.yScale = 0.5
    self.addChild(testNode!)
  }
  override func touchesMoved(touches: NSSet, withEvent event: UIEvent) {

    var nodeTouched = SKNode()
    var currentNodeTouched = SKNode()

    for touch: AnyObject in touches {
        let location = touch.locationInNode(self)

        nodeTouched = self.nodeAtPoint(location)
        testNode?.position = location
    }
}

 override func touchesEnded(touches: NSSet, withEvent event: UIEvent) {

    var touch: UITouch = touches.anyObject() as UITouch
    var location: CGPoint = touch.locationInNode(self) as CGPoint


}

Answer 1

这是我写的一个简单的例子，它通过在游戏循环中模拟它的速度而不是直接设置位置来移动精灵。这使精灵更具动态性（即您可以“扔”它，并在拖动精灵时让它与其他物理体交互）。不需要角度计算，我只是计算在一段时间内将精灵移动到触摸位置所需的速度。在这种情况下，我将时间设置为 1/60，以便立即应用运动，使对象看起来非常灵敏。

import SpriteKit
class GameScene: SKScene {
    var sprite: SKSpriteNode!
    var touchPoint: CGPoint = CGPoint()
    var touching: Bool = false
    override func didMoveToView(view: SKView) {
        self.physicsBody = SKPhysicsBody(edgeLoopFromRect: self.frame)
        sprite = SKSpriteNode(color: UIColor.redColor(), size: CGSize(width: 50, height: 50))
        sprite.physicsBody = SKPhysicsBody(rectangleOfSize: sprite.size)
        sprite.position = CGPoint(x: self.size.width/2.0, y: self.size.height/2.0)
        self.addChild(sprite)
    }
    override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
        let touch = touches.first as! UITouch
        let location = touch.locationInNode(self)
        if sprite.frame.contains(location) {
            touchPoint = location
            touching = true
        }
    }
    override func touchesMoved(touches: Set<NSObject>, withEvent event: UIEvent) {
        let touch = touches.first as! UITouch
        let location = touch.locationInNode(self)
        touchPoint = location
    }
    override func touchesEnded(touches: Set<NSObject>, withEvent event: UIEvent) {
        touching = false
    }

    override func update(currentTime: CFTimeInterval) {
        if touching {
            let dt:CGFloat = 1.0/60.0
            let distance = CGVector(dx: touchPoint.x-sprite.position.x, dy: touchPoint.y-sprite.position.y)
            let velocity = CGVector(dx: distance.dx/dt, dy: distance.dy/dt)
            sprite.physicsBody!.velocity=velocity
        }
    }
}

您可以自己微调物理计算以获得所需的效果。但是这段代码应该足以让你开始。我能想到的一些增强功能可能会限制速度，这样物体在释放时就不会移动得太快。为触摸拖动添加延迟，以便移动精灵但在最后意外停止，继续抛出对象。

Answer 2

如果您正在拖动精灵，那么这应该不会太难。听起来您需要在游戏中添加一些物理特性。

在设置 yScale 后将其添加到 testNode

testNode.physicsBody = SKPhysicsBody(rectangleOfSize: testNode.size)

现在运行游戏。您应该会看到 testNode 掉到屏幕底部。您不希望这种情况发生，因此我们将屏幕边框作为物理体。

在didMoveToView的顶部添加这个

self.physicsBody = SKPhysicsBody(edgeLoopFromRect: self.frame)

这将使屏幕边缘包含您的 testNode。你现在应该可以把它捡起来扔了

您可能需要稍微调整一下这个公式才能真正抛出精灵。

您可能需要比较上一次触摸位置和当前触摸位置，获取它们之间的角度并对精灵施加脉冲。

Answer 3

这里是 Swift 3.0/ 4.0 版本的答案

class GameScene: SKScene {
var sprite: SKSpriteNode!
var touchPoint: CGPoint = CGPoint()
var touching: Bool = false
override func didMove(to view: SKView) {
    let physicsFrame = CGRect(x: 0, y: 50, width: self.frame.size.width, height: self.frame.size.height - 100)
    self.physicsBody = SKPhysicsBody.init(edgeLoopFrom: physicsFrame)
    sprite = SKSpriteNode(color: UIColor.red, size: CGSize(width: 50, height: 50))
    sprite.physicsBody = SKPhysicsBody.init(rectangleOf: sprite.size)
    sprite.position = CGPoint(x: self.size.width/2.0, y: self.size.height/2.0)
    self.addChild(sprite)
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    let touch = touches.first!
    let location = touch.location(in:self)
    if sprite.frame.contains(location) {
        touchPoint = location
        touching = true
    }
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    let touch = touches.first!
    let location = touch.location(in: self)
    touchPoint = location
}

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
    touching = false
}
override func update(_ currentTime: TimeInterval) {
    if touching {
        let dt:CGFloat = 1.0/60.0
        let distance = CGVector(dx: touchPoint.x-sprite.position.x, dy: touchPoint.y-sprite.position.y)
        let velocity = CGVector(dx: distance.dx/dt, dy: distance.dy/dt)
        sprite.physicsBody!.velocity=velocity
    }
}}