如何解决在 Swift/SpriteKit 中碰撞时的空气曲棍球圆环脉冲?
背景:我正在 SpriteKit (Swift) 中开发一个简单的游戏/应用程序。它类似于空气曲棍球,但带有磁铁(如名为 Klask 的桌面游戏)。我已经花了很多时间添加商店、广告、菜单等。到目前为止,这对我来说是一个有趣的学习项目。
当前方法:当球员/槌击球时,我对球施加脉冲。这个脉冲(它接受一个 CGVector(dx:..,dy:..))是由帧到帧的触摸移动/位置计算的。因此,例如,如果玩家向东北方向移动木槌并且检测到球与玩家之间发生碰撞,则球将直接向东北方向移动(向上和向右)。
问题:这并没有考虑到玩家何时夹球,这会导致扭曲效果。玩家会期望球向基于球撞击位置的方向移动玩家用槌子(圆形)而不是触摸的方向(通常效果很好)。
期望的实现(来自 Acceleroto 的 Air Hockey 的演示):
当前实现/代码:
// In player class
override func touchesMoved(_ touches: Set<UITouch>,with event: UIEvent?)
{
bottomTouchIsActive = true
var releventTouch:UITouch!
//convert set to kNown type
let touchSet = touches
//get array of touches so we can loop through them
let orderedtouches = Array(touchSet)
for touch in orderedtouches
{
//if we've not yet found a relevent touch
if releventTouch == nil
{
//look for a touch that is in the activeArea (Avoid touches by opponent)
if activeArea.contains(CGPoint(x: touch.location(in: parent!).x,y: touch.location(in: parent!).y + frame.height * 0.24))
{
isUserInteractionEnabled = true
releventTouch = touch
}
else
{
releventTouch = nil
}
}
}
if (releventTouch != nil) && lastTouchTimeStamp != nil
{
//get touch position and relocate player
let location = CGPoint(x: releventTouch!.location(in: parent!).x,y: releventTouch!.location(in: parent!).y + frame.height * 0.24)
position = location
//find old location and use pythagoras to determine length between both points
let oldLocation = CGPoint(x: releventTouch!.prevIoUsLocation(in: parent!).x,y: releventTouch!.prevIoUsLocation(in: parent!).y + frame.height * 0.24)
let xOffset = location.x - oldLocation.x
let yOffset = location.y - oldLocation.y
let vectorLength = sqrt(xOffset * xOffset + yOffset * yOffset)
let seconds = releventTouch.timestamp - lastTouchTimeStamp!
let veLocity = 0.015 * Double(vectorLength) / seconds
//to calculate the vector,the velcity needs to be converted to a CGFloat
let veLocityCGFloat = CGFloat(veLocity)
// NSUserDefaults for more direct access in collision detection
let forceSaveDX = UserDefaults.standard
forceSaveDX.set(veLocityCGFloat * xOffset / vectorLength,forKey: "BottomForceDX")
forceSaveDX.synchronize()
let forceSaveDY = UserDefaults.standard
forceSaveDY.set(veLocityCGFloat * yOffset / vectorLength,forKey: "BottomForceDY")
forceSaveDY.synchronize()
//Only apply an impulse if the touch is active.
delegate?.bottomTouchIsActive(bottomTouchIsActive,fromBottomPlayer: self)
//update latest touch time for next calculation
lastTouchTimeStamp = releventTouch.timestamp
}
else if (releventTouch != nil) && lastTouchTimeStamp == nil
{
//get touch position and relocate player
let location = CGPoint(x: releventTouch!.location(in: parent!).x,y: releventTouch!.prevIoUsLocation(in: parent!).y + frame.height * 0.24)
let xOffset = location.x - oldLocation.x
let yOffset = location.y - oldLocation.y
let vectorLength = sqrt(xOffset * xOffset + yOffset * yOffset)
//update latest touch time for next calculation
lastTouchTimeStamp = releventTouch.timestamp
}
}
// In main gameScene
func didBegin(_ contact: SKPhysicsContact)
{
if (contact.bodyA.categoryBitMask == BodyType.ball.rawValue && contact.bodyB.categoryBitMask == BodyType.player.rawValue) && (contact.bodyA.contactTestBitMask == 25 || contact.bodyB.contactTestBitMask == 25) && bottomTouchForCollision == true
{
ball!.physicsBody!.applyImpulse(CGVector(dx: CGFloat(UserDefaults.standard.float(forKey: "BottomForceDX")),dy: CGFloat(UserDefaults.standard.float(forKey: "BottomForceDY"))))
}
}
我为这么长的问题道歉,很难解释问题是什么。但基本上我只需要使用球击中球员槌的位置而不是触球方向来计算冲量。如果这可以直接在碰撞检测功能中完成,那就更好了,因为不会有专门用于计算触摸方向的额外帧。我被困了一段时间。
我认为最好将触球速度和球击中槌的位置结合起来,以获得最真实的冲击力。我只是不知道如何以这种方式计算向量。我愿意接受所有想法!
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