你好。
我有多个碰撞问题。有一颗子弹击中了敌人(红色矩形)。然后,它+分数。有一个螺旋线(红色圆圈) 被推测为当敌人(红色矩形)触摸场景时触发场景结束。
在这种情况下,当敌人击中螺旋桨时,螺旋桨将起作用,场景结束,然后我们进入菜单屏幕。但是,当子弹击中敌人时,同样的事情也会发生,我也不知道为什么。
现在,这是我的代码:
struct PhysicsCategory { static let None : UInt32 = 0 static let All : UInt32 = UInt32.max static let enemyOne : UInt32 = 0b1 static let enemyTwo : UInt32 = 0b1 static let bullet : UInt32 = 0b10 static let spiral : UInt32 = 0b111 } spiral.physicsBody = SKPhysicsBody(rectangleOfSize: spiral.size) spiral.physicsBody?.categoryBitMask = PhysicsCategory.spiral spiral.physicsBody?.contactTestBitMask = PhysicsCategory.enemyOne spiral.physicsBody?.collisionBitMask = PhysicsCategory.None ... enemyOne.physicsBody = SKPhysicsBody(rectangleOfSize: enemyOne.size) enemyOne.physicsBody?.dynamic = true enemyOne.physicsBody?.categoryBitMask = PhysicsCategory.enemyOne enemyOne.physicsBody?.contactTestBitMask = PhysicsCategory.bullet | PhysicsCategory.spiral enemyOne.physicsBody?.collisionBitMask = PhysicsCategory.None ... bullet.physicsBody = SKPhysicsBody(circleOfRadius: bullet.size.width / 2) bullet.physicsBody?.dynamic = true bullet.physicsBody?.categoryBitMask = PhysicsCategory.bullet bullet.physicsBody?.contactTestBitMask = PhysicsCategory.enemyOne bullet.physicsBody?.collisionBitMask = PhysicsCategory.None bullet.physicsBody?.usesPreciseCollisionDetection = true ... func bulletDidCollideWithEnemy(bullet: SKSpriteNode, enemyOne: SKSpriteNode) { scoreOnScreen.text = String(score) score++ bullet.removeFromParent() enemyOne.removeFromParent() } func enemyDidCollideWithSpiral(enemyOne: SKSpriteNode, spiral: SKSpriteNode) { let transition = SKTransition.revealWithDirection(SKTransitionDirection.Down, duration: 1.0) let skView = self.view! as SKView let scene = MenuScene(size: skView.bounds.size) scene.scaleMode = SKSceneScaleMode.AspectFill skView.presentScene(scene, transition: SKTransition.crossFadeWithDuration(0.5)) } // Did Begin Contact func didBeginContact(contact: SKPhysicsContact) { var firstBody : SKPhysicsBody var secondBody : SKPhysicsBody var thirdBody : SKPhysicsBody var fourthBody : SKPhysicsBody if contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask { firstBody = contact.bodyA secondBody = contact.bodyB } else { firstBody = contact.bodyB secondBody = contact.bodyA } if contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask { thirdBody = contact.bodyA fourthBody = contact.bodyB } else { thirdBody = contact.bodyB fourthBody = contact.bodyA } if (firstBody.categoryBitMask & PhysicsCategory.enemyOne != 0) && (secondBody.categoryBitMask & PhysicsCategory.bullet != 0) { bulletDidCollideWithEnemy(firstBody.node as SKSpriteNode, enemyOne : secondBody.node as SKSpriteNode) } if (thirdBody.categoryBitMask & PhysicsCategory.enemyOne != 0) && (fourthBody.categoryBitMask & PhysicsCategory.spiral != 0) { enemyDidCollideWithSpiral(thirdBody.node as SKSpriteNode, spiral : fourthBody.node as SKSpriteNode) }
现在,我知道那是一团糟,但是有人可以帮助我吗?我认为问题与bodyA.categoryBitMask和bodyB设置为不同的东西有关,甚至认为它们是相同的(?)。我不知道。任何人?
这里有几个问题。
您在定义类别时要避免对其进行轻松测试。 您正在以无法获得所需唯一答案的方式测试类别。 您已经通过尝试在一个联系人中跟踪多达四个主体来混淆了代码。任何接触都将始终只有两个实体。 让我们一次解决一个问题…
1.定义类别 您想要定义碰撞类别,以便游戏中的每种身体都在 遮罩中使用自己的位。(使用Swift的二进制 文字表示法是个好主意,但是您要定义重叠的类别。)以下 是非重叠类别的示例:
struct PhysicsCategory: OptionSet { let rawValue: UInt32 init(rawValue: UInt32) { self.rawValue = rawValue } static let enemy = PhysicsCategory(rawValue: 0b001) static let bullet = PhysicsCategory(rawValue: 0b010) static let spiral = PhysicsCategory(rawValue: 0b100) }
我OptionSet为此使用Swift 类型,因为它使创建 和测试唯一值的组合变得容易。 与an相比,它确实使定义我的类型及其成员的语法有点笨拙enum,但这 也意味着我以后不必做很多装箱和拆箱原始值的工作, 特别是如果我还像这样使便捷访问器:
extension SKPhysicsBody { var category: PhysicsCategory { get { return PhysicsCategory(rawValue: self.categoryBitMask) } set(newValue) { self.categoryBitMask = newValue.rawValue } } }
另外,我在代码中使用了二进制文字表示法,额外的空格和零, 以便轻松地确保每个类别都有自己的位- enemy仅获得最低有效位,bullet下一个等等。
2&3.测试和跟踪类别 我喜欢使用两层方法来联系处理程序。首先,我要检查 碰撞的类型-是子弹/敌人碰撞还是子弹/螺旋 碰撞或螺旋/敌人碰撞?然后,如有必要,我检查 一下碰撞中的哪个身体。就 计算而言,这并不会花费太多,而且在我的代码的每一点上都非常清楚正在发生什么
func didBegin(_ contact: SKPhysicsContact) { // Step 1. To find out what kind of contact we have, // construct a value representing the union of the bodies' categories // (same as the bitwise OR of the raw values) let contactCategory: PhysicsCategory = [contact.bodyA.category, contact.bodyB.category] if contactCategory.contains([.enemy, .bullet]) { // Step 2: We know it's an enemy/bullet contact, so there are only // two possible arrangements for which body is which: if contact.bodyA.category == .enemy { self.handleContact(enemy: contact.bodyA.node!, bullet: contact.bodyB.node!) } else { self.handleContact(enemy: contact.bodyB.node!, bullet: contact.bodyA.node!) } } else if contactCategory.contains([.enemy, .spiral]) { // Here we don't care which body is which, so no need to disambiguate. self.gameOver() } else if contactCategory.contains([.bullet, .spiral]) { print("bullet + spiral contact") // If we don't care about this, we don't necessarily // need to handle it gere. Can either omit this case, // or set up contactTestBitMask so that we // don't even get called for it. } else { // The compiler doesn't know about which possible // contactCategory values we consider valid, so // we need a default case to avoid compile error. // Use this as a debugging aid: preconditionFailure("Unexpected collision type: \(contactCategory)") } }
为什么要使用if语句和OptionSet类型的contains()方法?为什么不这样做switch,使测试值的语法短很多呢?
switch contactCategory { case [.enemy, .bullet]: // ... case [.enemy, .spiral]: // ... // ... default: // ... }
使用switch此处的问题在于它会测试您的OptionSets是否相等 -也就是说,案例1会在if触发contactCategory == [.enemy, .bullet],而在if则不会触发[.enemy, .bullet, .somethingElse]。
对于在此示例中定义的联系人类别,这不是问题。但是类别/接触式位掩码系统的一个不错的功能之一 是您可以在单个项目上编码多个类别。例如:
struct PhysicsCategory: OptionSet { // (don't forget rawValue and init) static let ship = PhysicsCategory(rawValue: 0b0001) static let bullet = PhysicsCategory(rawValue: 0b0010) static let spiral = PhysicsCategory(rawValue: 0b0100) static let enemy = PhysicsCategory(rawValue: 0b1000) } friendlyShip.physicsBody!.category = [.ship] enemyShip.physicsBody!.category = [.ship, .enemy] friendlyBullet.physicsBody!.category = [.bullet] enemyBullet.physicsBody!.category = [.bullet, .enemy]
在这种情况下,您可能有一个类别为[.ship,.bullet,.enemy]—的联系人,并且如果您的联系人处理逻辑专门针对进行测试[.ship, .bullet],您会错过它。如果contains改为使用,则可以 测试您关心的特定标志,而无需关心是否存在其他标志。
[.ship, .bullet]