The skeletal model moves

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Created Apr ’25

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I want to make a model with added bones move by dragging it with gestures，This is a model exported using Blender， What I understand is using IKComponent, but I don't know how to use it specifically

Answered by Vision Pro Engineer in 834762022

Hi @LazyCoder

Here's a snippet to get you started. The snippet enables you to manipulate a humanoid robot by dragging sphere's attached to its hands ands feet. The snippet uses the model available for download here. For more information on the model format, read Rigging a Model for Motion Capture.

To run the snippet, download the model and include it in your project. The snippet looks for a model named "biped_robot".

Please reach out if you have followup questions. If this answers your question please accept the answer.

Here's the source for ImmersiveView. I'll share the code for the SampleModel in my next response.

struct ImmersiveView: View {
    @State fileprivate var model = SampleModel()
    @State var subscription: EventSubscription?
    @State var humanEntity = Entity()
    
    @State var leftHandTarget:ModelEntity
    @State var rightHandTarget:ModelEntity
    @State var leftFootTarget:ModelEntity
    @State var rightFootTarget:ModelEntity
    let root = Entity()
    
    init() {
        let alpha = 0.65
        leftHandTarget = Self.createTargetEntity(color: .blue.withAlphaComponent(alpha))
        rightHandTarget = Self.createTargetEntity(color: .red.withAlphaComponent(alpha))
        leftFootTarget = Self.createTargetEntity(color: .orange.withAlphaComponent(alpha))
        rightFootTarget = Self.createTargetEntity(color: .green.withAlphaComponent(alpha))
    }
    
    var body: some View {
        RealityView { content in
            guard let character = try? await ModelEntity(named: "biped_robot") else {
                fatalError("Failed to load character model.")
            }
            
            character.transform.translation = [0, 0, -1]
            character.transform.scale = SIMD3(repeating: 1.0)
            humanEntity = character
            
            content.add(character)
            
            try? model.setUpIK(character)
            
            subscription = content.subscribe(to: SceneEvents.Update.self) { event in
                model.updateIK()
            }
            
            root.addChild(character)
            
            addTargetEntities()
            
            root.position = [0, 1.5, -1]
            content.add(root)
            
            initializePositions(for: character)
        }.gesture(DragGesture().targetedToAnyEntity()
            .onChanged { event in
                let entity = event.entity
                guard let parent = entity.parent else {return}
                
                entity.position = event.convert(event.location3D, from: .local, to: parent)
                syncPositions()
            }
        )
    }
    
    private func addTargetEntities() {
        setInitialModelPose()
        
        root.addChild(leftHandTarget)
        root.addChild(rightHandTarget)
        root.addChild(leftFootTarget)
        root.addChild(rightFootTarget)
    }
    
    private func setInitialModelPose() {
        leftHandTarget.position = [1.014, 0.543, -1.109]
        rightHandTarget.position = [-1.014, 0.543, -1.109]
        leftFootTarget.position = [0.31, -1.063, -1.07]
        rightFootTarget.position = [-0.31, -1.063, -1.07]
    }
    
    private func initializePositions(for character: ModelEntity) {
        Task {
            // wait for model to load
            var attempts = 0
            let maxAttempts = 10
            let retryDelayInMilliseconds = 100
            
            while model.setUpTargets(character) == false {
                attempts += 1
                
                if attempts >= maxAttempts {
                    fatalError("Model failed to load in time.")
                }
                
                try? await Task.sleep(for: .milliseconds(retryDelayInMilliseconds))
            }
            
            syncPositions()
        }
    }
    
    private func syncPositions() {
        model.setTargetPosition(limb: .leftHand, targetPosition: leftHandTarget.position(relativeTo: humanEntity))
        model.setTargetPosition(limb: .rightHand, targetPosition: rightHandTarget.position(relativeTo: humanEntity))
        model.setTargetPosition(limb: .leftFoot, targetPosition: leftFootTarget.position(relativeTo: humanEntity))
        model.setTargetPosition(limb: .rightFoot, targetPosition: rightFootTarget.position(relativeTo: humanEntity))
    }
    
    private static func createTargetEntity(color: UIColor) -> ModelEntity {
        let radius:Float = 0.05
        let entity = ModelEntity(
            mesh: .generateSphere(radius: radius),
            materials: [SimpleMaterial(color: color, roughness: 0.9, isMetallic: false)]
        )
        
        entity.components.set(CollisionComponent(shapes: [.generateSphere(radius: radius)]))
        entity.components.set(InputTargetComponent())
        entity.components.set(HoverEffectComponent())
        
        return entity
    }
}

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Answer 1

Vision Pro Engineer OP

Apple

Apr ’25

Accepted Answer