hitTest(_:options:) don't recognize nodes behind ARKit planes - swift

Question

I place an object on a wall, then try to recognize tap on it, but hit test returns 0 objects. When I change Z position of the object and place it a little bit closer to cam, it's recognized well, but this isn't a solution, because planes are always changing and it can cover the object in any moment. How can I made hitTest work correctly and recognize my nodes behind planes? Or, maybe, I use the wrong method?
fileprivate func addNode(atPoint point: CGPoint) {
let hits = sceneView.hitTest(point, types: .existingPlaneUsingExtent)
if hits.count > 0, let firstHit = hits.first, let originNode = originNode {
let node = originNode.clone()
sceneView.scene.rootNode.addChildNode(node)
node.position = SCNVector3Make(firstHit.worldTransform.columns.3.x, firstHit.worldTransform.columns.3.y, firstHit.worldTransform.columns.3.z)
let resize = simd_float4x4(SCNMatrix4MakeScale(0.2, 0.2, 0.2))
let rotation = simd_float4x4(SCNMatrix4MakeRotation(.pi / 2, -1, 0, 0))
let transform = simd_mul(firstHit.worldTransform, resize)
let finalTransform = simd_mul(transform, rotation)
node.simdTransform = finalTransform
addedNodes.insert(node)
}
}
func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
guard let touch = touches.first else {
print("Unable to identify touches on any plane. Ignoring interaction...")
return
}
let touchPoint = touch.location(in: sceneView)
let hits = sceneView.hitTest(touchPoint, options: [SCNHitTestOption.boundingBoxOnly: true])
let filtered = hits.filter({ addedNodes.contains($0.node) })
print("\(hits.count) vs \(filtered.count), \(hits.first?.node.name ?? "no name")")
if let node = filtered.first?.node {
node.removeFromParentNode()
addedNodes.remove(node)
return
}
addPictureToPlane(atPoint: touchPoint)
}
addedNodes - set with added objects. When I added translating transform with changing Z coordinate at least on 0.05 (close to the camera) detecting working good. At least before plane changing and moving ahead the node.

Answer 1

I believe what you need to do is change your SCNHitTestSearchModeparameter which allows you to set:
Possible values for the searchMode option used with hit-testing
methods.
static let searchMode: SCNHitTestOption
Whereby:
The value for this key is an NSNumber object containing the raw
integer value of an SCNHitTestSearchMode constant.
From the Apple Docs there are three possible options you can use here:
case all
The hit test should return all possible results, sorted from nearest
to farthest.
case any
The hit test should return only the first object found, regardless of
distance.
case closest
The hit test should return only the closes object found.
Based on your question therefore, you would likely need to to utilise the all case.
As such your hitTest function would probably need to look something like this (remembering that self.augmentedRealityView refers to an ARSCNView):
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
//1. Get The Current Touch Location
guard let currentTouchLocation = touches.first?.location(in: self.augmentedRealityView) else { return }
//2. Perform An SCNHitTest Setting The SearchMode To 1 (All) Which Returns A List Of Results Sorted From Nearest To Farthest
if #available(iOS 11.0, *) {
let hitTestResults = self.augmentedRealityView.hitTest(currentTouchLocation, options: [SCNHitTestOption.searchMode: 1])
//3. Loop Through The Results & Get The Nodes
for index in 0..<hitTestResults.count{
let node = hitTestResults[index]
print(node)
}
}
}