ios - 如何在 SpriteKit 中检测不同类型的碰撞

Question

我想在 SpriteKit 中检测两种不同类型的碰撞:

当 ballOne 击中 goalOne 且 ballTwo 击中 goalTwo 时:

到目前为止，我已经添加了不同的物理类别:

struct physicsCategory {
    static let ballOne :UInt32 = 0x1 << 0
    static let goalOne :UInt32 = 0x1 << 1
    static let ballTwo :UInt32 = 0x1 << 2
    static let goalTwo :UInt32 = 0x1 << 3
}

这是我类(class)的相关部分:

class gameScene: SKScene, SKPhysicsContactDelegate {

    var borderBody:SKPhysicsBody!

    var myscore:Int = 0
    var opponentScore:Int = 10

    override func sceneDidLoad() {

        super.sceneDidLoad()
        physicsWorld.contactDelegate = self

    }

    func didBegin(_ contact: SKPhysicsContact) {

        let firstBody = contact.bodyA.node as! SKSpriteNode
        let secondBody = contact.bodyB.node as! SKSpriteNode

        if ((firstBody.name == "ballOne") && (secondBody.name == "goalOne")) {
            collisionGoalOne(BallOne: firstBody, GoalOne: secondBody)
        }

        else {

        }
    }

    func collisionGoalOne(BallOne: SKSpriteNode, GoalOne: SKSpriteNode) {
        addScore()
    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {

        let touch = touches.first
        let touchLocation = touch!.location(in: self)

        let ballOne = childNode(withName: "ballOne") as! SKSpriteNode
        ballOne.physicsBody?.categoryBitMask = physicsCategory.ballOne
        ballOne.physicsBody?.collisionBitMask = physicsCategory.goalOne
        ballOne.physicsBody?.contactTestBitMask = physicsCategory.goalOne
        ballOne.physicsBody?.isDynamic = true

        let goalOne = childNode(withName: "goalOne") as! SKSpriteNode
        goalOne.physicsBody?.categoryBitMask = physicsCategory.goalOne
        goalOne.physicsBody?.collisionBitMask = physicsCategory.ballOne
        goalOne.physicsBody?.contactTestBitMask = physicsCategory.ballOne
        goalOne.physicsBody?.isDynamic = false        
    }

}

现在，当球与墙上的墙壁碰撞时，应用程序会崩溃

让 firstBody = contact.bodyA.node 为! SKSpriteNode

“无法将‘appName.gameScene’类型的值 (0x105320) 转换为‘SKSpriteNode’ (0x1877b5c)。”

很想了解为什么会发生这种崩溃，以及这是否是一种很好的碰撞处理方法。谢谢。

Answer 1

FirstBody 可能无法转换为 SKSpriteNode，因此只有在检查哪些节点发生碰撞后才创建该变量。

请注意，ballOne 可以是 bodyA 或 bodyB，因此请更改您的代码以检查这两种可能性。

我稍微修改了你的代码。希望这有帮助

if ((contact.bodyA.node?.name == "ballOne") && (contact.bodyB.node?.name == "goalOne")) {  
     let firstBody = contact.bodyA.node as! SKSpriteNode
     let secondBody = contact.bodyB.node as! SKSpriteNode
     collisionGoalOne(BallOne: firstBody, GoalOne: secondBody)
 } else if ((contact.bodyA.node?.name == "goalOne") && (contact.bodyB.node?.name == "ballOne")) {
     let firstBody = contact.bodyA.node as! SKSpriteNode
     let secondBody = contact.bodyB.node as! SKSpriteNode
     collisionGoalOne(BallOne: secondBody, GoalOne: firstBody)
}