我使用“Hello World”Sprite-kit 模板做了一个小测试项目，其中有一个由这些帧组成的图集动画:

-

我想展示这个骑士和它的动画。

我想设置一个 DYNAMIC 物理体。

所以我用了一个工具来分离单帧，我做了一个atlasc文件夹 所以代码应该是:

import SpriteKit
class GameScene: SKScene {
    var knight: SKSpriteNode!
    var textures : [SKTexture] = [SKTexture]()
    override func didMove(to view: SKView) {
        self.physicsWorld.gravity = CGVector(dx:0, dy:-2)
        let plist = "knight.plist"
        let genericAtlas = SKTextureAtlas(named:plist)
        let filename : String! = NSURL(fileURLWithPath: plist).deletingPathExtension!.lastPathComponent
        for i in 0 ..< genericAtlas.textureNames.count
        {
            let textureName = (String(format:"%@%02d",filename,i))
            textures.append(genericAtlas.textureNamed(textureName))
        }
        if textures.count>0 {
            knight = SKSpriteNode(texture:textures.first)
            knight.zPosition = 2
            addChild(knight)
            knight.position = CGPoint(x:self.frame.midX,y:self.frame.midY)
        }
        //
        self.setPhysics()
        let animation = SKAction.animate(with: textures, timePerFrame: 0.15, resize: true, restore: false)
        knight.run(animation, withKey:"knight")
    }
    func setPhysics() {
        knight.physicsBody = SKPhysicsBody.init(rectangleOf: knight.size)
        knight.physicsBody?.isDynamic = false
    }
}

输出是:

如您所见，physicsBody 是静态的，不考虑动画:这是正常的，因为在动画期间纹理会改变维度/大小，而我们不'更改 physicsBody 在 Action 期间保持不变。

根据来源，在 SKAction.animate 期间，没有允许更改 physicsBody 的方法。

虽然我们使用:

/**
Creates an compound body that is the union of the bodies used to create it.
*/
public /*not inherited*/ init(bodies: [SKPhysicsBody])

为我们的动画的每一帧创建 body ，这些 body 在场景中保持在一起，创造了一个丑陋的怪异情况，如下图所示:

因此，正确的做法应该是在动画期间拦截帧并动态更改 physicsBody。 我们还可以使用 SKScene 中的 update() 方法，但我在考虑扩展。

我的想法是将 animation Action 与 SKAction.group 结合起来，制作另一个自定义 Action 来检查第一个 Action 的执行情况，拦截与当前 Action 匹配的帧knight.texture 使用 textures 数组并更改 physicsBody 启动外部方法，在本例中为 setPhysicsBody。

然后，我写了这个:

extension SKAction {
    class func animateWithDynamicPhysicsBody(animate:SKAction, key:String, textures:[SKTexture], duration: TimeInterval, launchMethod: @escaping ()->()) ->SKAction {
        let interceptor = SKAction.customAction(withDuration: duration) { node, _ in
            if node is SKSpriteNode {
                let n = node as! SKSpriteNode
                guard n.action(forKey: key) != nil else { return }
                if textures.contains(n.texture!) {
                    let frameNum = textures.index(of: n.texture!)
                    print("frame number: \(frameNum)")
                    // Launch a method to change physicBody or do other things with frameNum
                    launchMethod()
                }
            }
        }
        return SKAction.group([animate,interceptor])
    }
}

添加此扩展，我们将代码的动画部分更改为:

 //
        self.setPhysics()
        let animation = SKAction.animate(with: textures, timePerFrame: 0.15, resize: true, restore: false)
        let interceptor = SKAction.animateWithDynamicPhysicsBody(animate: animation, key: "knight", textures: textures, duration: 60.0, launchMethod: self.setPhysics)
        knight.run(interceptor,withKey:"knight")
    }
    func setPhysics() {
        knight.physicsBody = SKPhysicsBody.init(rectangleOf: knight.size)
        knight.physicsBody?.isDynamic = false
    }

这终于成功了，输出是:

您是否知道获得此结果的更好方法或更优雅的方法？

最佳答案

就像我在评论中提到的那样，因为你在做盒装物理，所以给你的骑士添加一个子 SKSpriteNode 来处理物理的接触部分，并且只根据骑士的框架进行缩放:

(注意:这仅用于演示目的，我相信您可以想出一种更优雅的方式来处理多个 Sprite )

import SpriteKit
class GameScene: SKScene {
    var knight: SKSpriteNode!
    var textures : [SKTexture] = [SKTexture]()
    private var child = SKSpriteNode(color:.clear,size:CGSize(width:1,height:1))
    override func didMove(to view: SKView) {
        self.physicsWorld.gravity = CGVector(dx:0, dy:-2)
        let plist = "knight.plist"
        let genericAtlas = SKTextureAtlas(named:plist)
        let filename : String! = NSURL(fileURLWithPath: plist).deletingPathExtension!.lastPathComponent
        for i in 0 ..< genericAtlas.textureNames.count
        {
            let textureName = (String(format:"%@%02d",filename,i))
            textures.append(genericAtlas.textureNamed(textureName))
        }
        if textures.count>0 {
            knight = SKSpriteNode(texture:textures.first)
            knight.zPosition = 2
            addChild(knight)
            knight.position = CGPoint(x:self.frame.midX,y:self.frame.midY)
        }
        //
        self.setPhysics()
        let animation = SKAction.repeatForever(SKAction.animate(with: textures, timePerFrame: 0.15, resize: true, restore: false))
       knight.run(animation,withKey:"knight")
    }
    override func didEvaluateActions() {
        child.xScale = knight.frame.size.width
        child.yScale = knight.frame.size.height

    }
    func setPhysics() {
        child.physicsBody = SKPhysicsBody.init(rectangleOf: child.size)
        child.physicsBody?.isDynamic = false
        knight.addChild(child)
    }
}

处理基于纹理的物体。我会编写自定义动画来处理它:

extension SKAction
{
    static func animate(withPhysicsTextures textures:[(texture:SKTexture,body:SKPhysicsBody)], timePerFrame:TimeInterval ,resize:Bool, restore:Bool) ->SKAction {

        var originalTexture : SKTexture!;
        let duration = timePerFrame * Double(textures.count);

        return SKAction.customAction(withDuration: duration)
        {
            node,elapsedTime in
            guard let sprNode = node as? SKSpriteNode
            else
            {
                    assert(false,"animatePhysicsWithTextures only works on members of SKSpriteNode");
                    return;
            }
            let index = Int((elapsedTime / CGFloat(duration)) * CGFloat(textures.count))
            //If we havent assigned this yet, lets assign it now
            if originalTexture == nil
            {
                originalTexture = sprNode.texture;
            }


            if(index < textures.count)
            {
                sprNode.texture = textures[index].texture
                sprNode.physicsBody = textures[index].body
            }
            else if(restore)
            {
                sprNode.texture = originalTexture;
            }

            if(resize)
            {
                sprNode.size = sprNode.texture!.size();
            }

        }
    }
}


import SpriteKit
class GameScene: SKScene {
    var knight: SKSpriteNode!
    var textures = [texture:SKTexture,body:SKPhysicsBody]()
    override func didMove(to view: SKView) {
        self.physicsWorld.gravity = CGVector(dx:0, dy:-2)
        let plist = "knight.plist"
        let genericAtlas = SKTextureAtlas(named:plist)
        let filename : String! = NSURL(fileURLWithPath: plist).deletingPathExtension!.lastPathComponent
        for i in 0 ..< genericAtlas.textureNames.count
        {
            let textureName = (String(format:"%@%02d",filename,i))
            let texture = genericAtlas.textureNamed(textureName)
            let body = SKPhysicsBody(texture:texture)
            body.isDynamic = false
            textures.append((texture:texture,body:body))
        }
        if textures.count>0 {
            knight = SKSpriteNode(texture:textures.first.texture)
            knight.zPosition = 2
            addChild(knight)
            knight.position = CGPoint(x:self.frame.midX,y:self.frame.midY)
        }
        //
        let animation = SKAction.animate(withPhysicsTextures: textures, timePerFrame: 0.15, resize: true, restore: false)
        knight.run(animation, withKey:"knight")
    }
}

关于swift - Swift 3 中的动画图集和动态物理体，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/41292166/