Get the direction arrow toward the SCNNode once that node is not visible in ARCamera

问题

If ARCamera moving left, right, up or down and if that node becomes invisible in ARCamera. I want to indicate the arrow that you need to move camera up/down/right/left.

回答1:

    if let pointOfView = sceneView.pointOfView{
        let isMaybeVisible = sceneView.isNode((displayNode.presentation), insideFrustumOf: pointOfView)
        if isMaybeVisible{
            if arrowVisible{
                 arrow.removeFromParentNode()
            }
        }else{
            if !arrowVisible{
                 sceneView.pointOfView?.addChildNode(arrow)
            }
        }
    }

isNode(_:insideFrustumOf:) here checks if node is visible in ARCamera.
Use it inside renderer(_:updateAtTime:)

Edit: Arrow here is a node (3d arrow). Remember the point of arrow need to face -z axis

    let scene = SCNScene(named: "art.scnassets/arrow.dae")
    let arrow = scene?.rootNode.childNode(withName: "arrow", recursively: false)
    arrow.constraints = [SCNLookAtConstraint.init(target: node)]

来源：https://stackoverflow.com/questions/53083642/get-the-direction-arrow-toward-the-scnnode-once-that-node-is-not-visible-in-arca