ios - 在一段时间内手动移动节点

Question

我目前声明了以下函数，这些函数将节点移动到场景更新函数中调用的目标位置(在这种情况下，我不能使用SKAction.moveTo)

func moveTowardsPosition(targetPosition: CGPoint, withTimeInterval timeInterval: NSTimeInterval) {
    let currentPosition = self.position
    var deltaX = targetPosition.x - currentPosition.x
    var deltaY = targetPosition.y - currentPosition.y
    var maximumDistance = 3 * CGFloat(timeInterval)
    moveFromCurrentPosition(currentPosition, byDeltaX: deltaX, deltaY: deltaY, maximumDistance: maximumDistance)
}

func moveFromCurrentPosition(currentPosition: CGPoint, byDeltaX dx: CGFloat, deltaY dy: CGFloat, maximumDistance: CGFloat) {
    let targetPosition = CGPointMake(currentPosition.x + dx, currentPosition.y + dy)
    var distRemaining = hypot(dx, dy)
    if distRemaining < maximumDistance {
        position = targetPosition
    } else {
        let x = currentPosition.x * maximumDistance
        let y = currentPosition.y * maximumDistance
        position = CGPointMake(x, y)
    }
}

(这些是根据苹果的“冒险”游戏稍微修改的)

我的问题是 moveCurrentPosition 函数中的这些行。

let x = currentPosition.x * maximumDistance
let y = currentPosition.y * maximumDistance
position = CGPointMake(x, y)

基本上，我不知道将 x 和 y 设置为什么值，以便该位置代表正确的位置。 在苹果的示例中，他们将其乘以最大距离 - 角度。角度 var 是一个仅影响 Assets 旋转的值，但我的 Assets 是“静态”的并且没有多个位置 - 只有 1。

考虑到这一点，我将x和y设置为多少，以便它们代表正确的位置？

(您可以在此处查看 Apple 的示例: https://developer.apple.com/library/prerelease/ios/samplecode/Adventure-Swift/Listings/Swift_Adventure_Adventure_Shared_Sprites_Character_swift.html )

Answer 1

I currently have the following functions declared which moves a node to a target location which is called in the update function of the scene (In this situation, I can't use SKAction.moveTo)

在这种情况下，您不使用 SKActions 是正确的。我看到您正在尝试在不使用 SKActions 的情况下将节点移动到某个位置。我不太明白您发布的代码所遇到的问题。不过，我编写了一个小型示例项目，演示了在没有 SKActions 的情况下将节点移动到更新函数中的位置。在此示例项目中，我有一个移动到当前触摸位置的 Sprite 。您可以设置节点行进的速度以及应用速度的速率。您可以尝试调整速率以获得正确的游戏感觉。您还需要处理节点到达目标位置时的情况(同样，这取决于您的游戏)。

如果这有帮助和/或您有任何疑问，请告诉我。

import SpriteKit
class GameScene: SKScene {
    var sprite: SKSpriteNode!
    var travelPoint: CGPoint = CGPoint() //The point to travel to.
    let travelSpeed = CGVector(dx: 200, dy: 200) //The speed at which to travel.
    let rate:CGFloat = 0.1 //1.0 Completely responsive. 0.0 Completely unresponsive. I set this value to < 1 to smooth the application of motion.
    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)
        sprite.physicsBody?.affectedByGravity = false
        self.addChild(sprite)
    }
    override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
        let touch = touches.first as! UITouch
        let location = touch.locationInNode(self)
            travelPoint = location
    }
    override func touchesMoved(touches: Set<NSObject>, withEvent event: UIEvent) {
        let touch = touches.first as! UITouch
        let location = touch.locationInNode(self)
        travelPoint = location
    }
    override func update(currentTime: CFTimeInterval) {
        let disp = CGVector(dx: travelPoint.x-sprite.position.x, dy: travelPoint.y-sprite.position.y)
        let angle = atan2(disp.dy, disp.dx)
        let vel = CGVector(dx: cos(angle)*travelSpeed.dx, dy: sin(angle)*travelSpeed.dy)
        let relVel = CGVector(dx: vel.dx-sprite.physicsBody!.velocity.dx, dy: vel.dy-sprite.physicsBody!.velocity.dy)
        sprite.physicsBody!.velocity = CGVector(dx: sprite.physicsBody!.velocity.dx+relVel.dx*rate, dy: sprite.physicsBody!.velocity.dy+relVel.dy*rate)
    }
}

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