我只是好奇,有没有办法减慢沿场景中其他物体发射的粒子的速度。假设你有一个粒子发射器和一个精灵。精灵使用SKAction
移动。发射器正在发射。两个节点都将添加到场景中。如果将self.speed
设置为 0.5,则只有角色会变慢。发射器将继续以相同的速度发射。
除了使用 particleSpeed 属性之外,有没有办法以其他方式减慢速度,因为这会改变发射器的行为。
我的问题受到这个问题的启发:https://stackoverflow.com/a/41764180/3402095
通常SKEmitterNode
的速度涉及许多属性(xAcceleration
,yAcceleration
,particleSpeedRange
,particleScaleSpeed
..):
private func newExplosion() -> SKEmitterNode {
let explosion = SKEmitterNode()
let image = UIImage(named:"spark.png")!
explosion.particleTexture = SKTexture(image: image)
explosion.particleColor = SKColor.brown
explosion.numParticlesToEmit = 100
explosion.particleBirthRate = 450
explosion.particleLifetime = 2
explosion.emissionAngleRange = 360
explosion.particleSpeed = 100
explosion.particleSpeedRange = 50
explosion.xAcceleration = 0
explosion.yAcceleration = 0
explosion.particleAlpha = 0.8
explosion.particleAlphaRange = 0.2
explosion.particleAlphaSpeed = -0.5
explosion.particleScale = 0.75
explosion.particleScaleRange = 0.4
explosion.particleScaleSpeed = -0.5
explosion.particleRotation = 0
explosion.particleRotationRange = 0
explosion.particleRotationSpeed = 0
explosion.particleColorBlendFactor = 1
explosion.particleColorBlendFactorRange = 0
explosion.particleColorBlendFactorSpeed = 0
explosion.particleBlendMode = SKBlendMode.add
return explosion
}
因此,为了满足您的要求,我认为应该可以设置targetNode
:
/**
Normally the particles are rendered as if they were a child of the SKEmitterNode, they can also be rendered as if they were a child of any other node in the scene by setting the targetNode property. Defaults to nil (standard behavior).
*/
weak open var targetNode: SKNode?
您可以在Apple官方文档中找到更多详细信息。
一些代码示例:
class GameScene: SKScene {
var myNode :SKSpriteNode!
var myEmitter : SKEmitterNode!
override func didMove(to view: SKView) {
myNode = SKSpriteNode.init(color: .red, size: CGSize(width:100,height:100))
self.addChild(myNode)
myNode.position = CGPoint(x:self.frame.minX,y:self.frame.midY)
let changePos = SKAction.run{
[weak self] in
guard let strongSelf = self else { return }
if strongSelf.myNode.position.x > strongSelf.frame.maxX {
strongSelf.myNode.position.x = strongSelf.frame.minX
}
}
let move = SKAction.moveBy(x: 10.0, y: 0, duration: 0.5)
let group = SKAction.group([move,changePos])
myNode.run(SKAction.repeatForever(SKAction.afterDelay(1.0, performAction:group)))
let showExplosion = SKAction.repeatForever(SKAction.afterDelay(3.0, performAction:SKAction.run {
[weak self] in
guard let strongSelf = self else { return }
strongSelf.myEmitter = strongSelf.newExplosion()
strongSelf.addChild(strongSelf.myEmitter)
strongSelf.myEmitter.targetNode = strongSelf.myNode
strongSelf.myEmitter.particleSpeed = strongSelf.myNode.speed
print("emitter speed is: (strongSelf.myEmitter.particleSpeed)")
strongSelf.myEmitter.position = CGPoint(x:strongSelf.frame.midX,y:strongSelf.frame.midY)
strongSelf.myEmitter.run(SKAction.afterDelay(2.0, performAction:SKAction.removeFromParent()))
}))
self.run(showExplosion)
}
private func newExplosion() -> SKEmitterNode {
let explosion = SKEmitterNode()
let image = UIImage(named: "sparkle.png")!
explosion.particleTexture = SKTexture(image: image)
explosion.particleColor = UIColor.brown
explosion.numParticlesToEmit = 100
explosion.particleBirthRate = 450
explosion.particleLifetime = 2
explosion.emissionAngleRange = 360
explosion.particleSpeed = 100
explosion.particleSpeedRange = 50
explosion.xAcceleration = 0
explosion.yAcceleration = 0
explosion.particleAlpha = 0.8
explosion.particleAlphaRange = 0.2
explosion.particleAlphaSpeed = -0.5
explosion.particleScale = 0.75
explosion.particleScaleRange = 0.4
explosion.particleScaleSpeed = -0.5
explosion.particleRotation = 0
explosion.particleRotationRange = 0
explosion.particleRotationSpeed = 0
explosion.particleColorBlendFactor = 1
explosion.particleColorBlendFactorRange = 0
explosion.particleColorBlendFactorSpeed = 0
explosion.particleBlendMode = SKBlendMode.add
return explosion
}
func randomCGFloat(_ min: CGFloat,_ max: CGFloat) -> CGFloat {
return (CGFloat(arc4random()) / CGFloat(UINT32_MAX)) * (max - min) + min
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
myNode.speed = randomCGFloat(0.0,50.0)
print("new speed is: (myNode.speed)")
}
}
extension SKAction {
class func afterDelay(_ delay: TimeInterval, performAction action: SKAction) -> SKAction {
return SKAction.sequence([SKAction.wait(forDuration: delay), action])
}
class func afterDelay(_ delay: TimeInterval, runBlock block: @escaping () -> Void) -> SKAction {
return SKAction.afterDelay(delay, performAction: SKAction.run(block))
}
}
在此示例中,您可以看到应用于myNode
的速度如何涉及每次触摸屏幕时的速度myEmitter
,因为发射器具有使用 myNode
设置的 targetNode
属性,并且我还更改了particleSpeed
似乎更现实的减速/加速。