Dynamically Change Text of Realitykit Entity

RealityKit – Why ModelEntity doesn't change dynamically?

Fix the following errors and it will do the trick:

1. Use $ for timeAccumulate property wrapper in ContentView struct to get a binding struct.

   ARViewContainer(timeAccumulate: $timeAccumulate)
   

2. Then use @Binding attribute for timeAccumulate property in ARViewContainer struct.

   @Binding var timeAccumulate: Int
   

3. baseColor is still working in iOS 15 but it'll be irrelevant on iOS 16. So, use color instead:

   var material = SimpleMaterial()
   
   material.color = .init(tint: .white,
                       texture: .init(try! .load(named: "texture.png")))
   

Is there a way to programmatically change the material of an Entity that was created in Reality Composer?

Model entity is stored deeper in RealityKit's hierarchy, and as you said, it's Entity, not ModelEntity. So use downcasting to access mesh and materials:

import UIKit
import RealityKit

class ViewController: UIViewController {
    
    @IBOutlet var arView: ARView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let boxScene = try! Experience.loadBox()
        print(boxScene)
        
        let modelEntity = boxScene.steelBox?.children[0] as! ModelEntity
        let material = SimpleMaterial(color: .green, isMetallic: false)
        modelEntity.model?.materials = [material]
        
        let anchor = AnchorEntity()
        anchor.scale = [5,5,5]
        modelEntity.setParent(anchor)
        arView.scene.anchors.append(anchor)
    }
}

RealityKit – Rotating an Entity affects its Scale

You need a starting transform "point" and ending transform "point". If a value of referenceEntity (relativeTo) argument equal to nil it means relative to world space. Since the same 4x4 matrix slots are used for rotation values ​​as for scaling, when the model is rotated, its scale also changes at the same time, if there is a difference in scale.

For perpetual transform animation use some of RealityKit 2.0 tricks.

And, of course, there is a Trigonometry that was really conceived for perpetual orbiting.

Here's a correct version of your code:

import UIKit
import RealityKit
import Combine

class ViewController: UIViewController {

    @IBOutlet var arView: ARView!
    var cancellable: Cancellable? = nil
    let anchor = AnchorEntity()

    override func viewDidLoad() {
        super.viewDidLoad()

        cancellable = ModelEntity.loadAsync(named: "drummer.usdz").sink { _ in
                self.cancellable?.cancel()
            } receiveValue: { entity in
                self.anchor.addChild(entity)
                self.arView.scene.addAnchor(self.anchor)
                    
                let rotation = Transform(pitch: 0, yaw: .pi, roll: 0)
                entity.move(to: rotation,
                    relativeTo: entity,
                      duration: 5.0,
                timingFunction: .linear)
            }
    }
}

RealityKit – Wrong ModelEntity position

You can easily center a new text using the following logic:

import Cocoa
import RealityKit

class ViewController: NSViewController {
    
    @IBOutlet var arView: ARView!

    override func awakeFromNib() {
        arView.environment.background = .color(.black)
        
        let scenePlate = try! Experience.loadPlate()
        arView.scene.anchors.append(scenePlate)
        
        print(scenePlate)
        
        
        // Text replacement and centering
        let text = scenePlate.findEntity(named: "simpBld_text") as! ModelEntity
        
        text.model?.mesh = .generateText("Hello",
                                         extrusionDepth: 0.05,
                                         font: .systemFont(ofSize: 0.35))

        let boundingBox: BoundingBox? = text.model?.mesh.bounds
        let coord = ((boundingBox?.max)! - (boundingBox?.min)!) / 2
        text.position = -1 * [coord.x, coord.y, coord.z]
        text.position.y -= 0.07
    }
}

Here's scene hierarchy:

▿ '' : Plate, children: 1
  ⟐ SynchronizationComponent
  ⟐ Transform
  ⟐ AnchoringComponent
  ▿ '' : AnchorEntity, children: 2
    ⟐ SynchronizationComponent
    ⟐ Transform
    ⟐ AnchoringComponent
    ▿ '' : Entity, children: 1
      ⟐ SynchronizationComponent
      ⟐ Transform
      ▿ 'sign' : Entity, children: 4
        ⟐ SynchronizationComponent
        ⟐ Transform
        ▿ 'squareNoEditBorder_1' : Entity, children: 1
          ⟐ SynchronizationComponent
          ⟐ Transform
          ▿ 'simpBld_root' : ModelEntity
            ⟐ ModelComponent
            ⟐ SynchronizationComponent
            ⟐ Transform
        ▿ 'squareNoEditFace_1' : Entity, children: 1
          ⟐ SynchronizationComponent
          ⟐ Transform
          ▿ 'simpBld_root' : ModelEntity
            ⟐ ModelComponent
            ⟐ SynchronizationComponent
            ⟐ Transform
        ▿ 'squareNoEditGround_1' : Entity, children: 1
          ⟐ SynchronizationComponent
          ⟐ Transform
          ▿ 'simpBld_root' : ModelEntity
            ⟐ ModelComponent
            ⟐ SynchronizationComponent
            ⟐ Transform
        ▿ 'squareText_1' : Entity, children: 1
          ⟐ SynchronizationComponent
          ⟐ Transform
          ▿ 'simpBld_root' : Entity, children: 1
            ⟐ SynchronizationComponent
            ⟐ Transform
            ▿ 'simpBld_text' : ModelEntity
              ⟐ ModelComponent
              ⟐ SynchronizationComponent
              ⟐ Transform
    ▿ 'Ground Plane' : Entity
      ⟐ SynchronizationComponent
      ⟐ CollisionComponent
      ⟐ Transform
      ⟐ PhysicsBodyComponent

Apply a custom texture to Plane entity using RealityKit 2.0

You have to implement brand-new parameters instead of deprecated arguments:

func createBoard() {
    
    let planeMesh = MeshResource.generatePlane(width: 1,
                                              height: 1,
                                        cornerRadius: 0.05)
    
    var material = SimpleMaterial()
    
    material.color = try! .init(tint: .white,
                             texture: .init(.load(named: "img", in: nil)))
    material.metallic = .init(floatLiteral: 1.0)
    material.roughness = .init(floatLiteral: 0.5)

    let modelEntity = ModelEntity(mesh: planeMesh,
                             materials: [material])
    
    let anchor = AnchorEntity()
    anchor.addChild(modelEntity)
    arView.scene.anchors.append(anchor)
}

Also, you can use the following syntax:

var material = SimpleMaterial()
material.color.texture = .init(try! .load(named: "img", in: nil))

If you need mode details, read this post.

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