swift - 如何通过在屏幕的下半部分沿 y 轴移动手指来旋转彩色 Sprite ？

Question

代码:

for touch in touches{
        let location = touch.location(in: self)
        let maxTouchHeight = self.frame.midY

        if currentGameType == .wobble{
            main.zRotation = (location.y)/512
            if location.y > maxTouchHeight { return }
            }
        }
    }

因此，在一种乒乓游戏中，我尝试根据手指在 y 轴上的位置来旋转 Racket 。但是，我无法做到它只能在屏幕的下半部分工作，即旋转的两个末端位于屏幕的最顶部和最底部，但我希望顶部位于屏幕的顶部屏幕的下半部分。 (主要是乒乓 Racket )。

感谢任何帮助:)

Answer 1

经过评论的讨论和反复的答案更新，我为您提供了一个解决方案。如果有问题，请告诉我:

class GameScene: SKScene {

  let paddle = SKSpriteNode()
  let maximumRotation = CGFloat(45)

  override func didMove(to view: SKView) {
    paddle.color = .blue
    paddle.size = CGSize(width: 200, height: 15)

    let deg45 = CGFloat(0.785398)
    let degNeg45 = -deg45

    let constraint = [SKConstraint.zRotation(SKRange(lowerLimit: degNeg45, upperLimit: deg45))]
    paddle.constraints = constraint

    addChild(paddle)
  }

  override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    guard let location     = touches.first?.location(in: self)         else { return }
    guard let lastLocation = touches.first?.previousLocation(in: self) else { return }
    guard location.y < self.frame.midY                                 else { return }

    // Our vertical plots:
    let yVal  = location.y
    let lastY = lastLocation.y

    // How much we moved in a certain direction this frame:
    let deltaY = yVal - lastY

    // This value represents 100% of a 45deg angle:
    let oneHundredPercent = self.frame.height/2
    assert(oneHundredPercent != 0)

    // The % of 100%Val (45degrees) that we moved (in radians):
    let absY = abs(deltaY)
    let radToDegFactor = CGFloat(0.01745329252)
    let multiplier = (absY / oneHundredPercent) * radToDegFactor

    // I suggest a sensitivity of 2-4:
    let sensitivity = CGFloat(3) 
    let amountToRotate = maximumRotation * (multiplier * sensitivity)

    // Rotate the correct amount in the correct direction:
    if deltaY > 0 {
      // Rotate counter-clockwise:
      paddle.run(.rotate(byAngle: amountToRotate, duration: 0))
    } else {
      // Rotate clockwise:
      paddle.run(.rotate(byAngle: -amountToRotate, duration: 0))
    }
  }
}

只需打开一个新项目并尝试一下!

可能有更简单的方法来做到这一点，但这是我脑海中突然出现的方法。它也有点冗长，所以希望您可以逐步了解每个过程。