Swift + Physics:碰撞时的角度计算错误

Question

我有一个简单的SpriteKit应用程序,墙壁和球.两者都设置为SKPhysicsBody.

当我向一个方向施加力时,我希望球在碰撞时以相同的角度在墙壁上反射,但方向相反.

但有时我看到角度很奇怪.我玩了很多physicsBody属性,但无法解决它.有时第一次反射看起来很好,但是第三次​​或第六次反射,有时第一次反射是错误的角度.

我从不同的帖子中读到,人们有点自我计算的"正确方向".但我无法想象SpriteKits物理引擎无法做到这一点.

检查我的附图,了解我的意思.有人可以帮忙吗？我不想开始使用Box2d for Swift,因为看起来我很难融入Swift.

这是physicsWorld我的GameScene.swift文件中的init,其中所有元素都添加到:

self.physicsWorld.gravity = CGVectorMake(0, 0)

添加我的所有代码太多了,所以我添加了重要的部分.希望它足以分析.像皮球所有元素,墙壁是SKSpriteNode的

这是physicsBody球的代码:

self.physicsBody = SKPhysicsBody(circleOfRadius: Constants.Config.playersize+self.node.lineWidth)
self.physicsBody?.restitution = 1
self.physicsBody?.friction = 0
self.physicsBody?.linearDamping = 1
self.physicsBody?.allowsRotation = false
self.physicsBody?.categoryBitMask = Constants.Config.PhysicsCategory.Player
self.physicsBody?.collisionBitMask = Constants.Config.PhysicsCategory.Wall | Constants.Config.PhysicsCategory.Enemy
self.physicsBody?.contactTestBitMask = Constants.Config.PhysicsCategory.Wall | Constants.Config.PhysicsCategory.Enemy

这是墙的物理体:

el = SKSpriteNode(color: UIColor.blueColor(), size: CGSize(width: Constants.Config.wallsize, height: Constants.Config.wallsize))
el.physicsBody = SKPhysicsBody(rectangleOfSize: CGSize(width: Constants.Config.wallsize, height: Constants.Config.wallsize))
el.physicsBody?.dynamic = false
el.physicsBody?.categoryBitMask = Constants.Config.PhysicsCategory.Wall
el.physicsBody?.collisionBitMask = Constants.Config.PhysicsCategory.Player
el.physicsBody?.contactTestBitMask = Constants.Config.PhysicsCategory.Player

最后,我只是在球上调用applyImpulse函数physicsBody,使其在物理模拟中移动.

另请检查我附加的第二张图片/ gif.它使用简单的skphysics应用程序显示边缘碰撞问题,没有任何特殊参数化.只是一个带有球的矩形,一个矢量用作冲动.

使用appzYourLife的解决方案继承我完整的非工作代码.

class GameScene: SKScene {
private var ball:SKShapeNode!
override func didMoveToView(view: SKView) {
    let screen = UIScreen.mainScreen().bounds
    let p = UIBezierPath()
    p.moveToPoint(CGPointMake(0,0))
    p.addLineToPoint(CGPointMake(screen.width,0))
    p.addLineToPoint(CGPointMake(screen.width, screen.height))
    p.addLineToPoint(CGPointMake(0,screen.height))
    p.closePath()
    let shape = SKShapeNode(path: p.CGPath)
    shape.physicsBody = SKPhysicsBody(edgeLoopFromPath: p.CGPath)
    shape.physicsBody?.affectedByGravity = false
    shape.physicsBody?.dynamic = false
    shape.strokeColor = UIColor.blackColor()

    self.addChild(shape)

    ball = SKShapeNode(circleOfRadius: 17)
    ball.name = "player"
    ball.position = CGPoint(x: 20, y: 20)
    ball.fillColor = UIColor.yellowColor()
    ball.physicsBody = SKPhysicsBody(circleOfRadius: 17)
    ball.physicsBody?.angularDamping = 0
    ball.physicsBody?.linearDamping = 0
    ball.physicsBody?.restitution = 1
    ball.physicsBody?.friction = 0
    ball.physicsBody?.allowsRotation = false

    self.addChild(ball)
    self.ball.physicsBody?.applyImpulse(CGVector(dx: 2.4, dy: 9.7))
}

我刚刚意识到我的球精灵的质量和密度是零.为什么？即使设置它也保持为零.

Answer 1

Since i cannot imagine this is some unknown bug in SpriteKits physics engine, 
i very hope someone can help me here as this is a full stopper for me.

这是SpriteKits 物理引擎中的（已知）错误。但有时只是玩这些值会使这个错误消失 - 例如，每次击球时尝试改变球的速度（即使是很小的值）。

此处列出了另一个解决方案： Swift 中的 SpriteKit 物理 - 球靠墙滑动而不是反射

（和你一样的问题，已经从 2014 年开始，仍然没有解决..）

Answer 2

SpriteKit工作正常

我创建了一个简单的项目,它工作正常.

问题

正如@Sulthan在评论中已经建议的那样,我认为代码中的问题就是这一行

el.physicsBody = SKPhysicsBody(rectangleOfSize: CGSize(width: Constants.Config.wallsize, height: Constants.Config.wallsize))

在这里,您不是为场景创建物理边界,而是创建一个矩形物理主体,它与Ball生成不切实际行为的物理主体重叠.

要创建我的场景的物理边界,我只是使用它

physicsBody = SKPhysicsBody(edgeLoopFromRect: frame)

完整代码

顺便说一下,这是我项目的完整代码

class GameScene: SKScene {
    override func didMoveToView(view: SKView) {
        let ball = Ball()
        ball.position = CGPoint(x:frame.midX, y:frame.midY)
        addChild(ball)
        physicsBody = SKPhysicsBody(edgeLoopFromRect: frame)
        ball.physicsBody!.applyImpulse(CGVector(dx:50, dy:70))
        physicsWorld.gravity = CGVector(dx:0, dy:0)
    }
}

class Ball: SKSpriteNode {

    init() {
        let texture = SKTexture(imageNamed: "ball")
        super.init(texture: texture, color: .clearColor(), size: texture.size())

        let physicsBody = SKPhysicsBody(circleOfRadius: texture.size().width/2)
        physicsBody.restitution = 1
        physicsBody.friction = 0
        physicsBody.linearDamping = 0
        physicsBody.allowsRotation = false
        self.physicsBody = physicsBody
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

}

我也用scene.scaleMode = .ResizeFill在里面GameViewController.swift.