Collision Detection after Object Tracking

Additionally, can this even be done? I tracked an object (using the anchoring method and the target being the reference object), then spawn a digital arrow on this tracked object. Now I draw collision boxes around these spawned digital arrows - can I check for collisions between 2 such arrows that are spawned based on 2 different objects being tracked? I read earlier that anchored objects have a different coordinate and physical space, so I'm now questioning if this is the right way to check this. Any suggestions would be very helpful! Thank you

Hello @adityach

By default, AnchorEntity and its children exist in a separate physics simulation, and do not interact with other entities outside its hierarchy. However, AnchoringComponent has a physicsSimulation property that lets you configure this behavior. I suspect you need to set this property to .none, like so:

myAnchorEntity.anchoring.physicsSimulation = .none

This will allow your AnchorEntity and child entities to participate in the same physics simulation as the other entities in your scene.

Additionally, make sure you have successfully started a SpatialTrackingSession, as described in this thread.

Let me know if this helps!

So this is what I have as my SwiftUI code at the moment

import SwiftUI

import RealityKit

import RealityKitContent

struct DualObjectTrackingTest: View {

@State private var subs: [EventSubscription] = []

var body: some View {
    RealityView { content in
        if let immersiveContentEntity = try? await Entity(named: "SceneFind.usda", in: realityKitContentBundle) {
            content.add(immersiveContentEntity)
            print("Collision check started")
        }
    } update: { content in
        //if let cube = content.entities.first?.findEntity(named: "WhiteArrow") as? ModelEntity {
            let event = content.subscribe(to: CollisionEvents.Began.self) { collisionEvent in
                
                print("Collision has occured")
            }
            DispatchQueue.main.async {
                subs.append(event)
            }
        }
    }
}

How do I change the physics components of the entities that are in the scene that I am loading? I have 2 anchor components added to 2 transforms in my scene - Transform1 and Transform2. Both of these transforms have an anchoring component each with the target being set to a reference object anchor that I am using. I don't see any properties that I can configure inside Reality Composer Pro, so if I need to reach these particular transforms that have the anchoring components, how do I do that from inside my code?

It might be a very rudimentary question, but I'm learning swiftUI as I go so some guidance here would be very helpful!

Thank you again

Hey @adityach

You can use the findEntity API to retrieve a named Entity in your loaded scene. Once you have the entity with the component, you can access the AnchoringComponent like you would with any Entity. Something like this might work:

if let immersiveContentEntity = try? await Entity(named: "SceneFind.usda", in: realityKitContentBundle) {
    if let myEntity = immersiveContentEntity.findEntity(named: "MyEntityName"), var anchoring = myEntity.components[AnchoringComponent.self] {
        // do something with anchoring
        anchoring.physicsSimulation = .none
        // remember to set the component back on your entity (it is a value type)
        myEntity.components[AnchoringComponent.self] = anchoring
    }
}

Let me know if this helps!

Apologies for the multiple comments, I have now been able to fix the physics simulation issue. I'm now adding collision boxes and physics body components to the 2 entities that I am spawning on my 2 object anchors, and trying to detect a collision between the two when I place the 2 objects on top of each other. Does not seem to be working at the moment. Any advice on what I can do for this?

This is the code below that I'm using

struct DualObjectTrackingTest: View {

@State private var subs: [EventSubscription] = []

var body: some View {
    RealityView { content in
        if let immersiveContentEntity = try? await Entity(named: "SceneFind.usda", in: realityKitContentBundle) {
            content.add(immersiveContentEntity)
            print("Collision check started")
            
            if let Anchor1 = immersiveContentEntity.findEntity(named: "Object1"),
               var transform1 = Anchor1.components[AnchoringComponent.self],
               let Anchor2 = immersiveContentEntity.findEntity(named: "Object2"),
               var transform2 = Anchor2.components[AnchoringComponent.self] {
                transform1.physicsSimulation = .none
                transform2.physicsSimulation = .none
            }
        }
    } update: { content in
        let event = content.subscribe(to: CollisionEvents.Began.self) { collisionEvent in
            
            print("Collision HAS OCCURED!")
        }
            DispatchQueue.main.async {
                subs.append(event)
            }
        }
    }
}

I don't see any console logs indicating that the collision has occurred, even though the entities and their components (collision boxes) should technically be in the same coordinate and physical space..