どのようにしてオブジェクトを素早くエッジから跳ね返させるのですか

Question

「敵」をすべての境界から逸らすようにしようとしています。例えば、敵が画面の左、右、上、下に衝突すると、方向が変わるはずです。

これは私の現在のコードです：

import SpriteKit 
import GameplayKit 

struct Physics { 
    static let Enemy: UInt32 = 0x1 << 1 
    let BorderCategory : UInt32 = 0x1 << 2 
    let BottomCategory : UInt32 = 0x1 << 3 
    let BallCategory : UInt32 = 0x1 << 4 

} 

class GameScene: SKScene { 

    var Enemy = SKSpriteNode() 
    var gameStarted = Bool() 
    var gameState = "running" 
    var destX : CGFloat = 0.0 
    var destY : CGFloat = 0.0 
    var score = 0 

    override func didMove(to view: SKView) { 
     let borderBody = SKPhysicsBody(edgeLoopFrom: self.frame) 
     borderBody.friction = 0 
     self.physicsBody = borderBody 
     let screenSize: CGRect = UIScreen.main().bounds  // get the screen size 
     let screenWidth = screenSize.width     //get the width 
     let screenHeight = screenSize.height    //get the height 


     Enemy = SKSpriteNode(imageNamed: "red2") 
     Enemy.size = CGSize(width: 60, height: 70) 
     Enemy.position = (CGPoint(x: self.frame.width/6 - Enemy.frame.width, y: self.frame.height/10)) 

     Enemy.physicsBody = SKPhysicsBody(circleOfRadius: Enemy.frame.height/2) 
     Enemy.physicsBody?.categoryBitMask = Physics.Enemy 
     //Enemy.physicsBody?.categoryBitMask = Physics.Ground | Physics.wall 
     //Enemy.physicsBody?.contactTestBitMask = Physics.Ground | Physics.wall 
     Enemy.physicsBody?.affectedByGravity = false 
     Enemy.physicsBody?.isDynamic = true 


     self.addChild(Enemy) 
     Enemy.physicsBody?.velocity = CGVector(dx: 50, dy: 50) 

     if (Enemy.position.x == screenWidth) { 
      Enemy.physicsBody?.velocity = CGVector(dx: -50, dy: 0)  // change direction at edge DOESN'T WORK 
     } 

     if(Enemy.position.y == screenHeight){ 
      Enemy.physicsBody?.velocity = CGVector(dx: 0, dy: -50)  //change direction at edge DOESN'T WORK 
     } 
    } 

Answer 1

それは（ほとんどの場合）しないので、あなたの条件のため - オペレータに等しいの代わりに、より低い/大きい使用。

import SpriteKit 

class GameScene: SKScene { 
    override func didMoveToView(view: SKView) { 

     // Create enemy with physics body attached and add it to the scene 
     let enemy = SKSpriteNode(color: SKColor.greenColor(), size: CGSize(width: 20, height: 20)) 
     enemy.name = "enemy" 
     enemy.position = CGPoint(x: size.width/2, y: size.height/2) 
     enemy.physicsBody = SKPhysicsBody(rectangleOfSize: enemy.size) 
     enemy.physicsBody!.affectedByGravity = false 
     enemy.physicsBody!.linearDamping = 0 
     enemy.physicsBody!.mass = 0.1 
     enemy.physicsBody!.velocity = CGVector(dx: 150, dy: 0) 
     addChild(enemy) 
    } 

    override func didSimulatePhysics() { 
     let enemy = childNodeWithName("enemy")! 

     if (enemy.position.x > size.width && enemy.physicsBody!.velocity.dx > 0) 
      || (enemy.position.x < 0 && enemy.physicsBody!.velocity.dx < 0) { 
      enemy.physicsBody!.velocity.dx *= -1 
     } 
    } 
} 

Answer 2

いいえ、コードに基づいて、動作中のバウンドスプライトを作成しました。手動で方向を変更するのではなく、これを実現するために物理エンジンを使用しています（これはどうやってこれを行うべきかと思います）。

override func didMove(to view: SKView) { 
    let borderBody = SKPhysicsBody(edgeLoopFrom: frame) 
    borderBody.friction = 0 
    borderBody.categoryBitMask = Physics.wall 
    physicsBody = borderBody 
    let enemy = enemySprite(size: CGSize(width: 60, height: 70), position: CGPoint(x: frame.size.width/2, y: frame.size.height/2)) 
    addChild(enemy) 
    let force = SKAction.applyForce(CGVector(dx: 300, dy: 300) , duration: 0.1) 
    enemy.run(force) 
} 

func enemySprite(size: CGSize, position: CGPoint) -> SKSpriteNode { 
    let enemy = SKSpriteNode(color: SKColor.red(), size: CGSize(width: 60, height: 80)) 
    enemy.position = CGPoint(x: frame.width/2, y: frame.height/2) 
    enemy.physicsBody = SKPhysicsBody(circleOfRadius: enemy.frame.height/2) // A bit silly with circle, but you seem to have an image for this use 
    enemy.physicsBody?.categoryBitMask = Physics.enemy 
    enemy.physicsBody?.restitution = 1 
    enemy.physicsBody?.friction = 0 
    enemy.physicsBody?.collisionBitMask = Physics.wall 
    enemy.physicsBody?.affectedByGravity = false 
    enemy.physicsBody?.angularDamping = 0 
    enemy.physicsBody?.linearDamping = 0 
    return enemy 
} 

シーンを設定する方法も考慮してください。シーンサイズはビューサイズと同じですか？そうでなければシーンの物理学ボディはあなたがそれを期待するところでボールをバウンスさせません...