iOS RealityKit. Changing Entity's translation causes unexpected behaviour - swift

Question

I am trying to create some AR experience.
I load the Model with animations as an Entity. Lets call it a Toy.
I create an AnchorEntity.
I attach the Toy to the AnchorEntity. Up to this point everything works great.
I want the Toy to walk in random directions. And it does for the first time. Then it gets interesting, allow me to share my code:
First method uses a newly created Transform for the Toy with the modified translation x, y, to make the Toy move and that is it.
func walk(completion: #escaping () -> Void) {
guard let robot = robot else {
return
}
let currentTransform = robot.transform
guard let path = randomPath(from: currentTransform) else {
return
}
let (newTranslation , travelTime) = path
let newTransform = Transform(scale: currentTransform.scale,
rotation: currentTransform.rotation,
translation: newTranslation)
robot.move(to: newTransform, relativeTo: nil, duration: travelTime)
DispatchQueue.main.asyncAfter(deadline: .now() + travelTime + 1) {
completion()
}
}
We get that new Transform from the method below.
func randomPath(from currentTransform: Transform) -> (SIMD3<Float>, TimeInterval)? {
// Get the robot's current transform and translation
let robotTranslation = currentTransform.translation
// Generate random distances for a model to cross, relative to origin
let randomXTranslation = Float.random(in: 0.1...0.4) * [-1.0,1.0].randomElement()!
let randomZTranslation = Float.random(in: 0.1...0.4) * [-1.0,1.0].randomElement()!
// Create a translation relative to the current transform
let relativeXTranslation = robotTranslation.x + randomXTranslation
let relativeZTranslation = robotTranslation.z + randomZTranslation
// Find a path
var path = (randomXTranslation * randomXTranslation + randomZTranslation * randomZTranslation).squareRoot()
// Path only positive
if path < 0 { path = -path }
// Calculate the time of walking based on the distance and default speed
let timeOfWalking: Float = path / settings.robotSpeed
// Based on old trasnlation calculate the new one
let newTranslation: SIMD3<Float> = [relativeXTranslation,
Float(0),
relativeZTranslation]
return (newTranslation, TimeInterval(timeOfWalking))
}
The problem is that the value of Entity.transform.translation.y grows from 0 to some random value < 1. Always after the second time the walk() method is being called.
As you can see, every time the method is called, newTranslation sets the Y value to be 0. And yet the Toy's translation:
I am out of ideas any help is appreciated. I can share the whole code if needed.

Answer 1

I have managed to fix the issue by specifying parameter relativeTo as Toy's AnchorEntity:
toy.move(to: newTransform, relativeTo: anchorEntity, duration: travelTime)