用ARKit做碰撞檢測(cè)，其實(shí)也就是做3D碰撞檢測(cè)鸿秆。3D碰撞檢測(cè)需要涉及到比較復(fù)雜的數(shù)學(xué)知識(shí)酌畜，還好SceneKit給我們提供了很多方便的方法來(lái)實(shí)現(xiàn)3D碰撞檢測(cè)。接下來(lái)卿叽，我們用ARKit來(lái)實(shí)現(xiàn)一個(gè)簡(jiǎn)單的3D碰撞檢測(cè)

一桥胞、創(chuàng)建工程

*.png

我們選擇用Swift語(yǔ)言

二、將需要的模型文件拖進(jìn)工程

**.png

模型放在art.scnassets文件夾

三考婴、創(chuàng)建egg節(jié)點(diǎn)

創(chuàng)建egg節(jié)點(diǎn)，給節(jié)點(diǎn)添加物理屬性

    override func viewDidLoad() {
        super.viewDidLoad()
        sceneView.delegate = self
        sceneView.showsStatistics = true
        let scene = SCNScene(named: "art.scnassets/egg.scn")!
        let eggNode = scene.rootNode.childNode(withName: "egg", recursively: false)
        //節(jié)點(diǎn)位置
        eggNode?.position = SCNVector3(5,0,-40)
        //創(chuàng)建physicBody
        let body = SCNPhysicsBody(type: .static, shape: SCNPhysicsShape(node: eggNode!, options: nil))
        //是否受重力影響
        body.isAffectedByGravity = false
        eggNode?.physicsBody = body
        //物理特性
        eggNode?.physicsBody?.categoryBitMask = 3
        eggNode?.physicsBody?.contactTestBitMask = 2
        sceneView.scene.rootNode.addChildNode(eggNode!)
        sceneView.debugOptions = [ARSCNDebugOptions.showFeaturePoints,ARSCNDebugOptions.showWorldOrigin]
      //設(shè)置 SCNPhysicsContactDelegate
        sceneView.scene.physicsWorld.contactDelegate = self
    }

四缎罢、點(diǎn)擊屏幕創(chuàng)建子彈節(jié)點(diǎn)

  override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        
        let geometry = SCNSphere(radius: 0.1)
        geometry.firstMaterial?.diffuse.contents = UIColor.red
        let buttleNode = SCNNode(geometry: geometry)
        
        guard let sceneView = self.view as? ARSCNView else {
            return
        }
        guard let pointView = sceneView.pointOfView else {
            return
        }
        let transform = pointView.transform
        //子彈射向的位置
        buttleNode.position = SCNVector3((-transform.m31-transform.m41),(-transform.m32-transform.m42),(-transform.m33-transform.m43))
        //創(chuàng)建鋼體
        let body = SCNPhysicsBody(type: .dynamic, shape: SCNPhysicsShape(node: buttleNode, options: nil))
        //是否受重力影響
        body.isAffectedByGravity = false
        
        buttleNode.physicsBody = body
      //子彈飛行速度
        buttleNode.physicsBody?.applyForce(SCNVector3( (-transform.m31) * 50,(-      transform.m32) * 50,(-transform.m33) * 50), asImpulse: true)
        buttleNode.physicsBody?.categoryBitMask = 2
        buttleNode.physicsBody?.contactTestBitMask = 3
    sceneView.scene.rootNode.addChildNode(buttleNode)
        
    }

五策精、實(shí)現(xiàn)SCNPhysicsContactDelegate

var Target: SCNNode? //碰撞之後的結(jié)果

//    當(dāng)被添加了 physicsBody 的節(jié)點(diǎn) 相互碰觸的時(shí)候 調(diào)用這個(gè)方法
func physicsWorld(_ world: SCNPhysicsWorld, didBegin contact: SCNPhysicsContact){
        let nodeA = contact.nodeA  //第一次子彈
        let nodeB = contact.nodeB //第二個(gè)蛋
        if nodeA.physicsBody?.contactTestBitMask == 2 {
            Target = nodeA //沒(méi)射中 留下的是子彈 
        }else if nodeB.physicsBody?.contactTestBitMask == 3{
            Target = nodeB //射中了 留下的是蛋
        }

    //這個(gè)效果通過(guò)創(chuàng)建scnp文件選擇
    let confetti = SCNParticleSystem(named: "art.scnassets/smoke.scnp", inDirectory: nil)

如下圖：

***.png

        confetti?.loops = false
        confetti?.particleLifeSpan = 4
        confetti?.emitterShape = Target?.geometry
        
        let confetNode = SCNNode()
        confetNode.addParticleSystem(confetti!) //節(jié)點(diǎn)上添加的特效
        confetNode.position = contact.contactPoint //兩個(gè)節(jié)點(diǎn)碰撞后作用的地方
        sceneView.scene.rootNode.addChildNode(confetNode)
        Target?.removeFromParentNode()
    }

六蔽午、運(yùn)行

好了及老，一個(gè)ARKit碰撞射擊游戲就這么簡(jiǎn)單的完成范抓，有沒(méi)有很happy
效果圖：
撞擊前是一個(gè)完整的蛋

i.png

撞擊后變?yōu)橐豢|青煙

ii.png