ios - Swift 和 Sprite Kit - 如何测量 Sprite 移动的总距离？

Question

在我的游戏中，玩家 Sprite 连续向上移动，因为我在更新函数中设置了 Sprite 的速度:

override func update(_ currentTime: TimeInterval) {
...

  player.physicsBody!.velocity.dy = max(player.physicsBody!.velocity.dy, 650 * gameGain)

}

现在我想测量 Sprite 走过的总距离。有什么方法/方法可以这样做，还是我必须创建一个变量来手动计算距离，例如

var distance:Float
override func update(_ currentTime: TimeInterval) {


  player.physicsBody!.velocity.dy = max(player.physicsBody!.velocity.dy, 650 * gameGain)

  distance += 650

}

提前致谢!

Answer 1

如果你对起始位置到当前位置的距离感兴趣，可以记住起始位置，然后计算距离:

let startPosition: CGPoint
var distance: CGFloat

init(startLocation: CGPoint) {
    self.startPosition = startPosition
    distance = 0
}

// Calculate the distance between two points using Pythagoras. You can make your code clean, by moving this into an extension for CGPoint.
private func distance(point1: CGPoint, point1: CGPoint) -> CGFloat {
    let dx = point1.x - point2.x
    let dy = point1.y - point2.y
    return sqrt(dx * dx + dy * dy);
}

override func update(_ currentTime: TimeInterval) {
    // Move the sprite
    let newPlayerPosition = player.position
    distance = distance(point1: newPlayerPosition, point2: startPosition)
}