Collaborative 3D Model Manipulation in visionOS

import SwiftUI
import RealityKit

// MARK: - Assembly open/close helpers

extension Entity {
    /// Move manipulation to children so each part is individually grabbable.
    func openAssembly() {
        components.remove(ManipulationComponent.self)
        components.remove(InputTargetComponent.self)

        for child in children {
            var manipulation = ManipulationComponent()
            manipulation.releaseBehavior = .stay
            child.components.set(manipulation)
            child.components.set(InputTargetComponent(allowedInputTypes: .all))
            // CollisionComponent is required for input to work.
            if child.components[CollisionComponent.self] == nil {
                child.generateCollisionShapes(recursive: false)
            }
        }
    }

    /// Collapse back to a single manipulable root entity.
    func closeAssembly() {
        for child in children {
            child.components.remove(ManipulationComponent.self)
            child.components.remove(InputTargetComponent.self)
        }
        var manipulation = ManipulationComponent()
        manipulation.releaseBehavior = .stay
        components.set(manipulation)
        components.set(InputTargetComponent(allowedInputTypes: .all))
    }

    /// Add a ClippingComponent that clips to the positive-Z half of the entity.
    func enableClipping() {
        guard let bounds = self.visualBounds(relativeTo: self) as BoundingBox? else { return }
        let halfDepth = (bounds.max.z + bounds.min.z) / 2
        let clippedBounds = BoundingBox(
            min: SIMD3(bounds.min.x, bounds.min.y, bounds.min.z),
            max: SIMD3(bounds.max.x, bounds.max.y, halfDepth)
        )
        var clipping = ClippingComponent(bounds: clippedBounds)
        clipping.shouldClipChildren = true
        clipping.shouldClipSelf = true
        components.set(clipping)
    }

    func disableClipping() {
        components.remove(ClippingComponent.self)
    }
}

// MARK: - SwiftUI View

struct AssemblyView: View {
    @State private var rootEntity: Entity? = nil
    @State private var isOpen = false
    @State private var isClipped = false

    var body: some View {
        RealityView { content in
            let root = try? await Entity(named: "AirPodsProAssembly", in: .main)
            if let root {
                var manipulation = ManipulationComponent()
                manipulation.releaseBehavior = .stay
                root.components.set(manipulation)
                root.components.set(InputTargetComponent(allowedInputTypes: .all))
                root.generateCollisionShapes(recursive: true)
                content.add(root)
                rootEntity = root
            }
        }
        .toolbar {
            ToolbarItemGroup(placement: .bottomOrnament) {
                Button(isOpen ? "Close Assembly" : "Open Assembly") {
                    guard let root = rootEntity else { return }
                    isOpen ? root.closeAssembly() : root.openAssembly()
                    isOpen.toggle()
                }
                Button(isClipped ? "Remove Clip" : "Clip Interior") {
                    guard let root = rootEntity else { return }
                    isClipped ? root.disableClipping() : root.enableClipping()
                    isClipped.toggle()
                }
            }
        }
    }
}