如何使用 ARKit 识别用户是否点击了屏幕上显示的对象 - swift

Question

我是新手iOS编程。我想构建一个允许用户点击屏幕上显示的特定对象的应用程序。我正在对已显示的对象使用 addGestureRecognizer 以确定用户是否已被单击，然后我只想将另一个对象添加到屏幕。

这是我到目前为止所做的

objpizza = make2dNode(image:#imageLiteral(resourceName: "pizza"),width: 0.07,height: 0.07)
    objpizza.position = SCNVector3(0,0,-0.2)
    objpizza.name = "none"

    self.arView.addGestureRecognizer(UIGestureRecognizer(target: self, action: #selector(selectObject)))
    arView.scene.rootNode.addChildNode(objpizza)

这里是make2dNode函数只是调整对象

func make2dNode(image: UIImage, width: CGFloat = 0.1, height: CGFloat = 0.1) -> SCNNode {
    let plane = SCNPlane(width: width, height: height)
    plane.firstMaterial!.diffuse.contents = image
    let node = SCNNode(geometry: plane)
    node.constraints = [SCNBillboardConstraint()]
    return node
}

这是我在 self.arView.addGestureRecognizer(UIGestureRecognizer(target: self, action: #selector(selectObject)))

中实现时从未调用过的函数

@objc func selectObject() {

    print("Image has been selected")
}

Answer 1

您需要实施

let tapGesture = UITapGestureRecognizer(target: self, action: #selector(didTap(_:)))
arView.addGestureRecognizer(tapGesture)

用于识别用户是否被点击的函数

@obj func didTap(_ gesture: UITabGestureRecognizer){ 
  object2 = make2Node(image: nameOfimage, width: 0.07, height: 0.07)
  object2.position = SCNVector(0,0,0.2)
  arView.scene.rootNode.addChildNode(object2)

兄弟编码愉快

Answer 2

检测 SCNNode 上的触摸需要的不仅仅是向您的视图添加 UITapGestureRecogniser。

为了检测您触摸了哪个 SCNNode，您需要使用 SCNHitTest（结合您的 gestureRecognizer），它是：

The process of finding elements of a scene located at a specified point, or along a specified line segment (or ray).

SCNHitTest 查找：

SCNGeometry objects along the ray you specify. For each intersection between the ray and and a geometry, SceneKit creates a hit-test result to provide information about both the SCNNode object containing the geometry and the location of the intersection on the geometry’s surface.

好吧，你可能会想，但这在我的案例中是如何工作的？

好吧，让我们首先创建一个带有 SCNSphere 几何体的 SCNNode 并将其添加到我们的场景中。

//1. Create An SCNNode With An SCNSphere Geometry
let nodeOneGeometry = SCNSphere(radius: 0.2)

//2. Set It's Colour To Cyan
nodeOneGeometry.firstMaterial?.diffuse.contents = UIColor.cyan

//3. Assign The Geometry To The Node
nodeOne = SCNNode(geometry: nodeOneGeometry)

//4. Assign A Name For Our Node
nodeOne.name = "Node One"

//5. Position It & Add It To Our ARSCNView
nodeOne.position = SCNVector3(0, 0, -1.5)
augmentedRealityView.scene.rootNode.addChildNode(nodeOne)

你会在这里注意到，我已经为我们的 SCNNode 分配了一个名称，这使得跟踪它（例如通过 hitTest 识别它）变得容易得多。

现在我们已经将 SCNNode 添加到层次结构中，让我们像这样创建一个 UITapGestureRecognizer：

//1. Create A UITapGestureRecognizer & Add It To Our MainView
let tapGesture = UITapGestureRecognizer(target: self, action: #selector(checkNodeHit(_:)))
tapGesture.numberOfTapsRequired = 1
self.view.addGestureRecognizer(tapGesture)

现在我们已经完成了所有设置，我们需要创建我们的 checkNodeHit 函数来检测用户点击了哪个节点：

/// Runs An SCNHitTest To Check If An SCNNode Has Been Hit
///
/// - Parameter gesture: UITapGestureRecognizer
@objc func checkNodeHit(_ gesture: UITapGestureRecognizer){

    //1. Get The Current Touch Location In The View
    let currentTouchLocation = gesture.location(in: self.augmentedRealityView)

    //2. Perform An SCNHitTest To Determine If We Have Hit An SCNNode
    guard let hitTestNode = self.augmentedRealityView.hitTest(currentTouchLocation, options: nil).first?.node else { return }

    if hitTestNode.name == "Node One"{

        print("The User Has Successfuly Tapped On \(hitTestNode.name!)")

    }
}

现在，如果您想在用户点击的地方放置一个 SCNNode，您必须使用 ARSCNHitTest 来代替这样做，它提供：

Information about a real-world surface found by examining a point in the device camera view of an AR session.

通过执行此操作，我们可以使用结果的 worldTransform 属性将虚拟内容放置在该位置。

供您参考，worldTransform 是：

The position and orientation of the hit test result relative to the world coordinate system.

ARKit 中的定位可以像这样轻松可视化：

再次让我们看看如何使用它来放置虚拟对象：

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {

    //1. Get The Current Touch Location In Our ARSCNView & Perform An ARSCNHitTest For Any Viable Feature Points
    guard let currentTouchLocation = touches.first?.location(in: self.augmentedRealityView),
          let hitTest = self.augmentedRealityView.hitTest(currentTouchLocation, types: .featurePoint).first else { return }

    //2. Get The World Transform From The HitTest & Get The Positional Data From The Matrix (3rd Column)
    let worldPositionFromTouch = hitTest.worldTransform.columns.3

    //3. Create An SCNNode At The Touch Location
    let boxNode = SCNNode()
    let boxGeometry = SCNBox(width: 0.1, height: 0.1, length: 0.1, chamferRadius: 0)
    boxGeometry.firstMaterial?.diffuse.contents = UIColor.cyan
    boxNode.geometry = boxGeometry
    boxNode.position = SCNVector3(worldPositionFromTouch.x, worldPositionFromTouch.y, worldPositionFromTouch.z)

    //4. Add It To The Scene Hierachy
    self.augmentedRealityView.scene.rootNode.addChildNode(boxNode)

}

希望对您有所帮助...

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