swift - 如何使用图像帧 sprite kit swift 创建爆炸效果

Question

所以我创建了这款游戏，您必须在其中射击物体。现在，我有一个复制对象爆炸的图像集。我想调用这些图像按顺序出现，这样它看起来就像弹丸击中物体后发生的爆炸。显然，必须在射弹击中物体的确切位置调用图像。有谁知道如何做到这一点？这是一些代码。

func projectileDidCollideWithMonster(projectile:SKSpriteNode, monster:SKSpriteNode) {
    projectile.removeFromParent()
    monster.removeFromParent()

    playerScore = playerScore + 1
    playerScoreUpdate()

    if (playerScore > 100) {
        let reveal = SKTransition.crossFadeWithDuration(0.3)
        let gameOverScene = GameOverScene(size: self.size, won: true)
        self.view?.presentScene(gameOverScene, transition: reveal)
    }

}

func didBeginContact(contact: SKPhysicsContact) {
    var firstBody: SKPhysicsBody
    var secondBody: SKPhysicsBody
    if contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask {
        firstBody = contact.bodyA
        secondBody = contact.bodyB
    } else {
        firstBody = contact.bodyB
        secondBody = contact.bodyA
    }
    if (firstBody.categoryBitMask & UInt32(laserCategory)) != 0 && (secondBody.categoryBitMask & UInt32(monsterCategory)) != 0 {
        projectileDidCollideWithMonster(firstBody.node as SKSpriteNode, monster: secondBody.node as SKSpriteNode)
    }
    if playerScore > highScore() {
        saveHighScore(playerScore)
        println("New Highscore = " + highScore().description)
        highScoreLabel.text = "Best score: \(highScore().description)"
    } else {
        println("HighScore = " + highScore().description )  // "HighScore = 100"
    }
}


override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
    for touch: AnyObject in touches {
        let location = touch.locationInNode(self)
        let node = self.nodeAtPoint(location)

        if node.name == "muteSound" {
            if musicIsPlaying == true {
                backgroundMusicPlayer.stop()
                musicIsPlaying = false
            } else if musicIsPlaying == false {
                backgroundMusicPlayer.play()
                musicIsPlaying = true
            }
        } else {
            let touch = touches.anyObject() as UITouch
            let touchLocation = touch.locationInNode(self)

            let projectile = SKSpriteNode(imageNamed: "boom")
            projectile.setScale(0.6)
            projectile.position = player.position
            projectile.physicsBody = SKPhysicsBody(circleOfRadius: projectile.size.width/2)
            projectile.physicsBody?.dynamic = true
            projectile.physicsBody?.categoryBitMask = UInt32(laserCategory)
            projectile.physicsBody?.contactTestBitMask = UInt32(monsterCategory)
            projectile.physicsBody?.collisionBitMask = 0
            projectile.physicsBody?.usesPreciseCollisionDetection = true
            // 3 - Determine offset of location to projectile
            let offset = touchLocation - projectile.position
            // 4 - Bail out if you are shooting down or backwards
            if (offset.y < 0) { return }
            // 5 - OK to add now - you've double checked position
            addChild(projectile)
            // 6 - Get the direction of where to shoot
            let direction = offset.normalized()
            // 7 - Make it shoot far enough to be guaranteed off screen
            let shootAmount = direction * 1000
            // 8 - Add the shoot amount to the current position
            let realDest = shootAmount + projectile.position
            // 9 - Create the actions
            let actionMove = SKAction.moveTo(realDest, duration: 2.0)
            let actionMoveDone = SKAction.removeFromParent()

            if !isStarted {
                start()
            }else{
                projectile.runAction(SKAction.sequence([actionMove, actionMoveDone]))

            }
        }
    }
}

func addMonster() {
    let monster = SKSpriteNode(imageNamed: "box")
    monster.setScale(0.6)
    monster.physicsBody = SKPhysicsBody(rectangleOfSize: monster.size)
    monster.physicsBody?.dynamic = true
    monster.physicsBody?.categoryBitMask = UInt32(monsterCategory)
    monster.physicsBody?.contactTestBitMask = UInt32(laserCategory)
    monster.physicsBody?.collisionBitMask = 0
    monster.name = "box"

    var random : CGFloat = CGFloat(arc4random_uniform(320))
    monster.position = CGPointMake(random, self.frame.size.height + 10)
    self.addChild(monster)
}

Answer 1

对于爆炸，您可以创建一个 SKSpriteNode 来播放您提到的帧:

1. 您将需要图像作为 SKTexture 数组。你说你在图像集中得到了图像，所以最简单的事情可能是使用 for 循环创建一个数组，例如:

// I don't know how many images you've got, so I'll use 10.
var textures: [SKTexture] = []
for i in 0..<10 {
    let imageName = "explosion\(i)"
    textures.append(SKTexture(imageNamed: imageName))
}

或者，我建议的是创建图像的纹理图集。 (有关纹理图集的更多信息，请参阅 here)要创建图集，请创建一个扩展名为 .atlas 的文件夹，并将所有爆炸图像添加到其中。 (然后将其添加到您的项目中)。这是我编写的一个扩展，用于从纹理图集中获取您的 Sprite ，为动画做好准备:

extension SKTextureAtlas {
    func textureArray() -> [SKTexture] {
        var textureNames = self.textureNames as! [String]

        // They need to be sorted because there's not guarantee the
        // textures will be in the correct order.
        textureNames.sort { $0 < $1 }
        return textureNames.map { SKTexture(imageNamed: $0) }
    }
}

下面是如何使用它:

let atlas = SKTextureAtlas(named: "MyAtlas")
let textures = atlas.textureArray()

2. 现在您已经获得了纹理，您需要创建一个 SKSpriteNode 并为其设置动画:

let explosion = SKSpriteNode(texture: textures[0])

let timePerFrame = // this is specific to your animation.
let animationAction = SKAction.animateWithTextures(textures, timePerFrame: timePerFrame)
explosion.runAction(animationAction)

3. 将 Sprite 添加到场景中并正确定位。要将它添加到正确的位置，您可以在 SKPhysicsContact 上使用 contactPoint 变量，在检查它是射弹击中物体后。

func didBeginContact(contact: SKPhysicsContact) {
    // Other stuff...

    explosion.position = contact.contactPoint
    self.addChild(explosion)
}

希望对您有所帮助!