6、SpriteKit 之 SKCameraNode

SKCameraNode

• 当场景的尺寸需要超过屏幕，需要移动或者缩放去查看更多界面时，就可以是使用 SKCameraNode。
• 在 SKScene 中使用。SKScene 中的 camera 属性默认是 nil。需要自己去初始化赋值。
• SKCameraNode 的缩放比例是小于1放大，大于1缩小

lazy var myCamera = SKCameraNode()

override func didMove(to view: SKView) {
    super.didMove(to: view)
    
    myCamera.position = CGPoint(x: view.bounds.width * 0.5, y: view.bounds.height * 0.5)
    self.addChild(myCamera)
    self.camera = myCamera
}

移动镜头

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    super.touchesMoved(touches, with: event)
    guard let touch = touches.first else {
        return
    }
    let locPoint = touch.location(in: self)
    let prePoint = touch.previousLocation(in: self)
    let x = myCamera.position.x - (locPoint.x - prePoint.x)
    let y = myCamera.position.y - (locPoint.y - prePoint.y)
    let point = CGPoint(x: x, y: y)
    print("point:\(point)")
    self.camera?.position = point
}

缩放视图

var tempScale: CGFloat?
lazy var cameraScale: CGFloat = 1 {
    didSet {
        myCamera.xScale = cameraScale
        myCamera.yScale = cameraScale
    }
}
let minScale: CGFloat = 2
let maxScale: CGFloat = 0.5


override func didMove(to view: SKView) {
    super.didMove(to: view)
    
    let pinchGes = UIPinchGestureRecognizer(target: self, action: #selector(pinchGestureAction(pinchGes:)))
    view.addGestureRecognizer(pinchGes)
}
    
@objc func pinchGestureAction(pinchGes: UIPinchGestureRecognizer) {
    let location = pinchGes.location(in: self.view)
    let cameraLocation = self.convertPoint(fromView: CGPoint(x: -location.x, y: -location.y))
    let scale = pinchGes.scale
    let velocity = pinchGes.velocity
    switch pinchGes.state {
        case .began:
            pinchBeganAtLocation(loc: cameraLocation, scale: scale, velocity: velocity)
        case .changed:
            pinchChangedAtLocation(loc: cameraLocation, scale: scale, velocity: velocity)
        case .ended:
            pinchEndedAtLocation(loc: cameraLocation, scale: scale, velocity: velocity)
        default:
            break
    }
}
    
func pinchBeganAtLocation(loc: CGPoint, scale: CGFloat, velocity: CGFloat) {
    tempScale = scale
}
    
func pinchChangedAtLocation(loc: CGPoint, scale: CGFloat, velocity: CGFloat) {
    guard let tempScale = tempScale else {
        return
    }
    let deltaScale = (tempScale - scale)
    
    var lastScale = cameraScale
    lastScale += deltaScale
    if lastScale <= maxScale {
        lastScale = maxScale
    } else if lastScale >= minScale {
        lastScale = minScale
    }
    cameraScale = lastScale
    self.tempScale = scale
}
    
func pinchEndedAtLocation(loc: CGPoint, scale: CGFloat, velocity: CGFloat) {
    tempScale = nil
}