Can move only the last object placed in Scene - scenekit

Question

Hy! I can move only the last virtual object placed in scene. When i add another object, the previous object added remains static and i cannot do any action on it. Can you give me please give me a solution to move, scale, rotate what object i want when I touch it?

Answer 1

Seeing as you haven't posted any code, its hard to provide an exact answer.
However, in order to keep track of the current SCNNode you wish to use, when you load a model etc you could store it as a variable e.g:
var currentNode: SCNNode!
You could also use the name property of the node when you are loading your model to keep a more specific reference to it.
Here is an example of doing this:
/// Example Of Loading An SCNScene & Setting It As The Current Node
func loadModel(){
let modelPath = "Character.scn"
//1. Get The Reference To Our SCNScene & Get The Model Root Node
guard let model = SCNScene(named: modelPath),
let modelObject = model.rootNode.childNode(withName: "Root", recursively: false) else { return }
//2. Scale It
modelObject.scale = SCNVector3(0.4, 0.4, 0.4)
//3. Add It To The Scene & Position It 1.5m Away From The Camera
augmentedRealityView.scene.rootNode.addChildNode(modelObject)
modelObject.position = SCNVector3(0, 0, -1.5)
//4. Set It As The Current Node & Assign A Name
currentNode = modelObject
currentNode.name = "Character"
}
You can also make use of an SCNHitTest which:
Looks for 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.
This can be used to differentiate between which node(s) have been hit e.g:
/// Detects A Tap On An SCNNode
///
/// - Parameter gesture: UITapGestureRecognizer
#objc func detectTap(_ gesture: UITapGestureRecognizer){
//1. Get The Current Touch Point
let currentTouchPoint = gesture.location(in: self.augmentedRealityView)
//2a. Perform An SCNHitTest To Detect If An SCNNode Has Been Touched
guard let nodeHitTest = self.augmentedRealityView.hitTest(currentTouchPoint, options: nil).first else { return }
if nodeHitTest.node == currentNode{
print("The Current Node Has Been Touched")
}
//Or To See Which Node Has Been Touched
if nodeHitTest.node.name == "The Model"{
print("The Model Has Been Touched")
}
}
Another way you can handle this is to add a UITapGestureRecognizer to your view, and enable interaction based on the result e.g. setting the currentNode that way e.g:
/// Detects A Tap On An SCNNode & Sets It As The Current Node
///
/// - Parameter gesture: UITapGestureRecognizer
#objc func detectTap(_ gesture: UITapGestureRecognizer){
//1. Get The Current Touch Point
let currentTouchPoint = gesture.location(in: self.augmentedRealityView)
//2a. Perform An SCNHitTest To Detect If An SCNNode Has Been Touched
guard let nodeHitTest = self.augmentedRealityView.hitTest(currentTouchPoint, options: nil).first else { return }
//2b. Set It As The Current Node
currentNode = nodeHitTest.node
}
Then you can apply logic to ensure that only the currentNode moves etc:
/// Moves An SCNNode
///
/// - Parameter gesture: UIPanGestureRecognizer
#objc func moveNode(_ gesture: UIPanGestureRecognizer) {
//1. Get The Current Touch Point
let currentTouchPoint = gesture.location(in: self.augmentedRealityView)
//2. If The Gesture State Has Begun Perform A Hit Test To Get The SCNNode At The Touch Location
if gesture.state == .began{
//2a. Perform An SCNHitTest To Detect If An SCNNode Has Been Touched
guard let nodeHitTest = self.augmentedRealityView.hitTest(currentTouchPoint, options: nil).first else { return }
//2b. Get The SCNNode Result
if nodeHitTest.node == currentNode{
//3a. If The Gesture State Has Changed Then Perform An ARSCNHitTest To Detect Any Existing Planes
if gesture.state == .changed{
//3b. Get The Next Feature Point Etc
guard let hitTest = self.augmentedRealityView.hitTest(currentTouchPoint, types: .existingPlane).first else { return }
//3c. Convert To World Coordinates
let worldTransform = hitTest.worldTransform
//3d. Set The New Position
let newPosition = SCNVector3(worldTransform.columns.3.x, worldTransform.columns.3.y, worldTransform.columns.3.z)
//3e. Apply To The Node
currentNode.simdPosition = float3(newPosition.x, newPosition.y, newPosition.z)
}
}
}
}
This should be more than enough to point you in the right direction...