所以我正在试验 Sprite-kit，以构建主要角色可以跟随并收集硬币的圆形路径。我已经成功地定位了我的角色并让他跟随我的圆形路径。

我想要实现的是:

• 红球是主角[完成]
• 白色多边形是硬币

// Adding the big circle
let runway = SKSpriteNode(imageNamed: "runway")
runway.position = CGPointMake(CGRectGetMidX(frame), CGRectGetMidY(frame))
addChild(runway)
// Adding the player
player = SKSpriteNode(imageNamed: "player")
player.position = CGPointMake( CGRectGetMidX(frame) , (CGRectGetMidY(frame) + runway.size.width/2) )
// Calculating the initial position of the player and creating a circular path around it
let dx = player.position.x - frame.width / 2
let dy = player.position.y - frame.height / 2

let radian = atan2(dy, dx)
let playerPath = UIBezierPath(
    arcCenter: CGPoint(x: CGRectGetMidX(frame), y: CGRectGetMidY(frame)),
    radius: (runway.frame.size.width / 2) - 20,
    startAngle: radian,
    endAngle: radian + CGFloat(M_PI * 4.0),
    clockwise: true)

let follow = SKAction.followPath(playerPath.CGPath, asOffset: false, orientToPath: true, speed: 200)
player.runAction(SKAction.repeatActionForever(follow))

我现在的问题是，如何将我的硬币放在同一条路径上？？ 有没有一种方法可以使用相同的路径生成它们的位置，或者我应该为每个硬币创建一个特定的路径并每次提取路径 currentPoint ??

有没有更简单的方法来解决我的问题？？

谢谢

最佳答案

就像我说的，你需要知道路径的中心在哪里(在你的例子中是 CGPoint(x: frame.midX, y:frame.midY) 这是“中心”屏幕的)并且你必须知道半径(你在创建路径时已经计算了它)并且你需要一个角度来使光线从中心 (frame.midX,frame.midY)到圆周上的点 (coinX,coinY) 使 x 轴为正:

import SpriteKit

class GameScene: SKScene {

    let player = SKSpriteNode(color: .purpleColor(), size: CGSize(width: 30, height: 30))

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

        // Adding the big circle
        let runway = SKSpriteNode(color: .orangeColor(), size: CGSize(width: 150, height: 150))
        runway.position = CGPointMake(CGRectGetMidX(frame), CGRectGetMidY(frame))
        addChild(runway)
        // Adding the player

        player.position = CGPointMake( CGRectGetMidX(frame) , (CGRectGetMidY(frame) + runway.size.width/2) )
        addChild(player)
        // Calculating the initial position of the player and creating a circular path around it
        let dx = player.position.x - frame.width / 2
        let dy = player.position.y - frame.height / 2

        let radius = (runway.frame.size.width / 2) - 20.0

        let radian = atan2(dy, dx)
        let playerPath = UIBezierPath(
            arcCenter: CGPoint(x: CGRectGetMidX(frame), y: CGRectGetMidY(frame)),
            radius: radius,
            startAngle: radian,
            endAngle: radian + CGFloat(M_PI * 4.0),
            clockwise: true)

        let follow = SKAction.followPath(playerPath.CGPath, asOffset: false, orientToPath: true, speed: 200)
        player.runAction(SKAction.repeatActionForever(follow))

        let numberOfCoins = 8
        for i in 0...numberOfCoins {

            let coin = SKSpriteNode(color: .yellowColor(), size: CGSize(width: 10, height: 10))

            let angle = 2 * M_PI / Double(numberOfCoins) * Double(i)

            let coinX = radius * cos(CGFloat(angle))
            let coinY = radius * sin(CGFloat(angle))

             coin.position = CGPoint(x:coinX + frame.midX, y:coinY + frame.midY)
            addChild(coin)
        }
    }
}

只是一个旁注:在 Sprite-Kit 中，0 弧度的角度指定正 x 轴。并且正角度是在逆时针方向。来源 - Building Your Scene .

关于ios - Sprite-kit:如何在圆形路径上定位 Sprite ，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/36320422/