ios – 用物理创建雨动画

2023年12月27日 199次阅读

我目前正在使用SpriteKit游戏技术开发使用
Swift编写的iOS应用程序.在这个游戏中,雨滴从屏幕顶部下降到底部.当它们到达底部时,由physicsBody表示,它们应该返回到屏幕顶部的原始位置,允许动画在游戏的整个生命周期中继续.

因为我只需要几滴我就像这样创建它们：

let drop = SKSpriteNode(imageNamed: "drop")
drop.position = CGPointMake(x,y)
drop.physicsBody = SKPhysicsBody(rectangleOfSize: drop.size)
addChild(drop)

然后我创建了位掩码：

drop.physicsBody!.categoryBitmask = DropCategory
bottom.physicsBody!.categoryBitmask = BottomCategory
drop.physicsBody!.contactTestBitmask = BottomCategory

我添加了didBeginContact函数,当drop到达底部时我会收到通知.然后我的控制台显示“击中”.

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 == BlockCategory && secondBody.categoryBitMask == GroundCategory {
        println("hit ground")

        firstBody.node?.removeFromParent()
        let drop = SKSpriteNode(imageNamed: "drop")
        drop.name = "testNode"
        drop.position = CGPointMake(self.frame.width - self.frame.width/3*2, self.frame.height) // At start Position
        drop.physicsBody = SKPhysicsBody(rectangleOfSize: drop.size)
        drop.physicsBody?.categoryBitMask = BlockCategory
        drop.physicsBody?.contactTestBitMask = GroundCategory
        addChild(drop)
    }
}

但是,跌落的位置不会改变.没有语法错误,所以我的问题是什么？

如果我替换它：

firstBody.node!.position = CGPointMake(x, y)

有了这个：

firstBody.applyImpulse(CGVector)

它给了一滴冲动.我怎样才能使第一个选项正常工作？

最佳答案 您可以尝试在触及底部时删除节点,并再次在顶部添加新节点.加载纹理以便在单独的SKTexture变量中重用.像这样

let dropTexture = SKTexture(imageNamed: "drop.png")

像这样使用它

let drop = SKSpriteNode(texture: dropTexture)

然后在didBeginContact里面

func didBeginContact(contact: SKPhysicsContact) {
    println("collided")
    var bodyA : SKPhysicsBody!
    var bodyB : SKPhysicsBody!

    if contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask
    {
        bodyA = contact.bodyA!
        bodyB = contact.bodyB!
    }
    else
    {
        bodyB = contact.bodyA!
        bodyA = contact.bodyB!
    }

    if bodyA.categoryBitMask == bottomCategoryBitMask && bodyB.categoryBitMask == raindropCategoryBitMask
    {
        if bodyB.node?.parent != nil // Added line
        {
            bodyB.node?.removeFromParent()
            let drop = SKSpriteNode(imageNamed: "1.png")
            drop.name = "testNode"
            drop.position = CGPointMake(self.frame.width - self.frame.width/3*2, self.frame.height) // At start Position
            drop.physicsBody = SKPhysicsBody(rectangleOfSize: drop.size)
            drop.physicsBody?.categoryBitMask = raindropCategoryBitMask
            drop.physicsBody?.contactTestBitMask = bottomCategoryBitMask
            addChild(drop)
        }
    }
}
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