Swift Sprite 套件相机运动

Question

我在 Sprite Kit 中制作了一个专注于 SKSpriteNode 的相机。

Apple 有一个很棒的文档：Apple Document

但是，现在的camera是直接跟随SKSpriteNode的，而我想留一点余地。

例如触摸后SKSpriteNode上下移动，相机从原点开始缓慢跟随SKSpriteNode，最大距离Height为SKSpriteNode是半屏，当SKSpriteNode静止时，相机和SKSpriteNode移动回到原点。

另外节点的 PhysicBody 行为异常，远离其实际图像。我该如何解决？

这是我的代码：

class GameScene: SKScene, SKPhysicsContactDelegate {

var Player: SKSpriteNode!

var Platform0: SKSpriteNode!
var Platform1: SKSpriteNode!
var Platform2: SKSpriteNode!
var Platform3: SKSpriteNode!
var Platform4: SKSpriteNode!
var Platform5: SKSpriteNode!

var World: SKNode!
var Camera: SKNode!

override func didMoveToView(view: SKView) {
    /* Setup your scene here */

    self.physicsWorld.contactDelegate = self
    self.anchorPoint = CGPoint(x: 0.5, y: 0.1)

    self.World = SKNode()
    self.World.name = "World"
    addChild(self.World)
    self.Camera = SKNode()
    self.Camera.name = "Camera"
    self.World.addChild(self.Camera)

    SpawnPlatforms()
    SpawnPlayer()
}

func SpawnPlatforms() {

    Platform0 = SKSpriteNode (color: SKColor.greenColor(), size: CGSize(width: self.frame.size.width , height: 25))
    Platform0.position = CGPoint(x: self.frame.size.width / 2, y: 40)
    Platform0.zPosition = 1

    Platform0.physicsBody = SKPhysicsBody(rectangleOfSize:Platform0.size)
    Platform0.physicsBody?.dynamic = false
    Platform0.physicsBody?.allowsRotation = false
    Platform0.physicsBody?.restitution = 0
    Platform0.physicsBody?.usesPreciseCollisionDetection = true

    Platform0.physicsBody?.categoryBitMask = Platform0Category
    Platform0.physicsBody?.collisionBitMask = PlayerCategory
    Platform0.physicsBody?.contactTestBitMask = PlayerCategory

    World.addChild(Platform0)

    /// All other Platforms declared as the same above

}

func SpawnPlayer(){

    var Player1:SKTexture!
    var Player2:SKTexture!

    var Animation:SKAction!
    var AnimationRepeat:SKAction!

    Player1 = SKTexture(imageNamed: "Image.png")
    Player1.filteringMode = .Nearest
    Player2 = SKTexture(imageNamed: "Image2.png")
    Player2.filteringMode = .Nearest

    Animation = SKAction.animateWithTextures([Player1,Player2], timePerFrame: 0.5)
    AnimationRepeat = SKAction.repeatActionForever(Animation)

    Player = SKSpriteNode (imageNamed: "Image.png")
    Player.size = CGSize(width: 64, height: 64)
    Player.position = CGPoint(x: self.frame.size.width / 2, y: 80)
    Player.zPosition = 2

    Player.physicsBody = SKPhysicsBody(rectangleOfSize:CGSize(width: 35, height: 50))
    Player.physicsBody?.dynamic = true
    Player.physicsBody?.allowsRotation = false
    Player.physicsBody?.restitution = 0
    Player.physicsBody?.usesPreciseCollisionDetection = true
    Player.physicsBody?.velocity = CGVector(dx: 0, dy: -0.1)

    Player.physicsBody?.categoryBitMask = PlayerCategory
    Player.physicsBody?.collisionBitMask = Platform0Category
    Player.physicsBody?.contactTestBitMask = Platform0Category | Platform1Category | Platform2Category | Platform3Category | Platform4Category | Platform5Category

    Player.runAction(AnimationRepeat)
    World.addChild(Player)

}

override func didFinishUpdate() {

    Camera.position = CGPoint(x: Player.position.x, y: Player.position.y)
    self.centerOnNode(Camera)

}

func centerOnNode(node: SKNode) {

    let cameraPositionInScene: CGPoint = node.scene!.convertPoint(node.position, fromNode: World)

    node.parent!.position = CGPoint(x:node.parent!.position.x - cameraPositionInScene.x, y:node.parent!.position.y - cameraPositionInScene.y)

}

Answer 1

不要直接在centeronnode中声明位置，而是使用SKAction moveTo。

它有持续时间值。

将旧的 centerOnNode 函数替换为：

func centerOnNode(node: SKNode) {

    let cameraPositionInScene: CGPoint = node.scene!.convertPoint(node.position, fromNode: World)

    node.parent!..runAction(SKAction.moveTo(CGPoint(x:node.parent!.position.x - cameraPositionInScene.x, y:node.parent!.position.y - cameraPositionInScene.y), duration: 1))

}

应该可以，但抱歉，我还没有测试过。

更新 Swift 3

func centerOnNode(node: SKNode) {
    let cameraPositionInScene: CGPoint = node.scene!.convert(node.position, from: World)   
    node.parent!.run(SKAction.move(to: CGPoint(x:node.parent!.position.x - cameraPositionInScene.x, y:node.parent!.position.y - cameraPositionInScene.y), duration: 1))   
}

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