探索 RealityKit 调试器

2:45 - ClubView

/*
Abstract:
The full club patch. SwiftUI view, state, extensions and helpers.
*/

import SwiftUI
import RealityKit
import OSLog
import BOTanistAssets
import Combine
import Charts

struct ClubView: View {
    @State var state = ClubViewState()
    
    var body: some View {
        ZStack {
            RealityView { content in
                state.loadEnvironment()
                
                state.rootEntity.scale = SIMD3<Float>(repeating: 0.5)
                
                content.add(state.rootEntity)
            } update: { updateContent in
                if !state.doorSupervisor.doorsOpen {
                    state.transformIntoClub(content: updateContent)
                }
            }
        }
    }
}

@Observable
@MainActor
final public class ClubViewState: Sendable {
    let rootEntity = Entity()
    
    private var loadedEnvironmentRoot: Entity?
    private var robotRevolutionController: Entity?
    private var host: Entity?
    
    private(set) var doorSupervisor: DoorSupervisor {
        get {
            rootEntity.components[DoorSupervisor.self]!
        } set {
            rootEntity.components[DoorSupervisor.self] = newValue
        }
    }
    
    init() {
        RevolvingSystem.registerSystem()
        HoverSystem.registerSystem()
        TeleportationSystem.registerSystem()
        DanceMotivationSystem.registerSystem()
        
        rootEntity.name = "The B0T Club"
        rootEntity.components[DoorSupervisor.self] = DoorSupervisor(capacity: 9)
    }
    
    /// Load the existing garden assets
    func loadEnvironment() {
        guard loadedEnvironmentRoot == nil else {
            return
        }
        
        if let environment = try? Entity.load(named: "scenes/volume", in: BOTanistAssetsBundle) {
            environment.name = "Environment"
            self.loadedEnvironmentRoot = environment
            
            rootEntity.addChild(environment)
        }
    }
    
    /// Renovate the loaded environment to build our club
    func transformIntoClub(content: RealityViewContent) {
        guard !doorSupervisor.doorsOpen else {
            return
        }
        
        // Build a teleportation center and use it to spawn robots
        addTeleportationCenterToTheClub()
        
        // Haphazardly clean up the space by hiding anything un-club-like
        hideStuffInTheEnvironment()
        
        // Polish that floor and add some spin
        addRevolvingDanceFloorToTheClub()
        
        // Keep the robots moving in an orderly fashion
        addRobotRevolutionControllerToTheClub()
        
        // Install some attractors to entice robots to the dance floor
        addDanceFloorAttractors()
        
        // Set the mood
        addSpotlightsToTheClub()
        
        // Stock up on oil to keep the moves smooth
        addCounterToTheClub()
        
        // And add a huge Disco Ball, because...
        addDiscoBallToTheClub()
        
        // Let the party begin
        openDoors()
    }
    
    /// Construct a Teleportation Center and add it to the Club's root entity
    private func addTeleportationCenterToTheClub() {
        let teleportationCenter = Entity()
        teleportationCenter.name = "Teleportation Center"
        rootEntity.addChild(teleportationCenter)
        
        // Liven up the planters to look more like teleporters
        let positions: [SIMD3<Float>] = [[0.128, 0, 0.14], [-0.255, 0, 0.23], [0.05, 0, -0.17]]
        let colors: [(UIColor, UIColor)] = [(.green, .yellow), (.magenta, .purple), (.cyan, .blue)]
        for index in 0...2 {
            if let teleporter = rejigPlanter(identifier: String(index + 1), position: positions[index], colors: colors[index]) {
                teleportationCenter.addChild(teleporter)
            }
        }
        
        // Create a Control Center and provide a closure to handle robot spawning
        let teleportationControlCenter = ControlCenterComponent(
            initialValue: 10,
            interval: 5,
            rootEntity: rootEntity) { teleporter in
                self.spawnRobot(from: teleporter)
                self.countVisitor()
                
                // Have the host say hello
                if let hostCharacter = self.host?.components[AutomatonControl.self]?.character {
                    hostCharacter.transitionToAndPlayAnimation(.idle)
                    hostCharacter.transitionToAndPlayAnimation(.wave)
                }
        }
        
        // Assign the new control center component to the teleportation center entity
        teleportationCenter.components[ControlCenterComponent.self] = teleportationControlCenter
    }
    
    /// Transforms the visuals of the planters to look more teleporter-y
    private func rejigPlanter(identifier: String, position: SIMD3<Float>, colors: (UIColor, UIColor)) -> Entity? {
        if let rim = rootEntity.findEntity(named: "heroPlanter_rim_\(identifier)"),
           let dirt = rootEntity.findEntity(named: "dirt_hero_\(identifier)"),
           let rimModelComponent = rim.components[ModelComponent.self],
           var dirtModelComponent = dirt.components[ModelComponent.self] {
            // Apply the luminous material from the rims to the dirt (trust me it will look cool).
            dirtModelComponent.materials = rimModelComponent.materials
            dirt.components[OpacityComponent.self] = OpacityComponent(opacity: 0.7)
            dirt.components[ModelComponent.self] = dirtModelComponent
        }
        
        // Make a teleporter container entity
        let teleporter = Entity()
        teleporter.name = "Teleporter-T\(identifier)"
        teleporter.position = position
        teleporter.components[TeleporterComponent.self] = TeleporterComponent()
        
        // Add a particle emitter
        let radius: Float = 0.035
        var particleEmitter = ParticleEmitterComponent.Presets.teleporter
        particleEmitter.emitterShapeSize = .init(repeating: radius)
        particleEmitter.mainEmitter.color = .constant(.random(a: colors.0, b: colors.1))
        
        let particleEntity = Entity()
        particleEntity.orientation = .init(angle: -.pi / 2, axis: [1, 0, 0])
        particleEntity.components[ParticleEmitterComponent.self] = particleEmitter
        particleEntity.name = "Photons"
        particleEntity.scale = .init(repeating: 1)
        teleporter.addChild(particleEntity)
        
#if DEBUG
        // Add a debug marker in case we want to visually inspect this in the RealityKit Debugger
        teleporter.addDebugMarker(radius: radius, color: colors.0)
#endif
        
        return teleporter
    }
    
    /// adds a random robot to the club root, positioned at the provided point
    private func spawnRobot(from spawnPoint: Entity) {
        guard let robotCharacter = randomRobot() else {
            logger.error("Robot creation malfunction 🤖💥")
            return
        }
        
        let guest = Entity()
        
        guest.addChild(robotCharacter.characterParent)
        guest.position = spawnPoint.position(relativeTo: rootEntity)
        guest.components[Newcomer.self] = Newcomer()
        guest.components[AutomatonControl.self] = AutomatonControl(character: robotCharacter)
        
        rootEntity.addChild(guest)
        
        // Play a little flashy burst on the particle emitter
        if let particles = spawnPoint.findEntity(named: "Photons") {
            var component = particles.components[ParticleEmitterComponent.self]
            component?.burst()
            particles.components[ParticleEmitterComponent.self] = component
        }
    }
    
    /// misuses AppState as a robot factory - don't try this at home, or do, but don't ship it!
    private func randomRobot() -> RobotCharacter? {
        let robotMaker = AppState()
        
        // Use offsets from the loaded animation rig, with some random parts
        guard let skeleton = robotMaker.robotData.meshes[.body]?.findEntity(named: "rig_grp") as? ModelEntity else {
            logger.error("Failed to find a robot animation rig... all dancing in cancelled ❌🕺")
            return nil
        }
        
        robotMaker.randomizeSelectedRobot()
        
        guard let head = robotMaker.robotData.meshes[.head]?.clone(recursive: true),
              let body = robotMaker.robotData.meshes[.body]?.clone(recursive: true),
              let backpack = robotMaker.robotData.meshes[.backpack]?.clone(recursive: true) else {
            fatalError()
        }
        
        let robotCharacter = RobotCharacter(
            head: head,
            body: body,
            backpack: backpack,
            appState: robotMaker,
            headOffset: skeleton.pins["head"]?.position,
            backpackOffset: skeleton.pins["backpack"]?.position
        )
        
        // Pick a random robot name from the sequence
        robotCharacter.characterParent.name = RobotNames.next
        
        // Remove the character controller and animation state, as we'll manually control these
        robotCharacter.characterParent.components[CharacterControllerComponent.self] = nil
        AnimationState.handlers.removeAll()
        
        // The robots are here to chill, so actually, let's put their backpacks in the cloakroom
        backpack.removeFromParent()
        
        // Say Hi
        robotCharacter.transitionToAndPlayAnimation(.wave)
        
        return robotCharacter
    }
    
    /// Update capacity when we have a visitor
    private func countVisitor() {
        var management = self.doorSupervisor
        management.visitorCount += 1
        self.doorSupervisor = management
    }
    
    /// Find and hide a bunch of stuff in the loaded environment
    private func hideStuffInTheEnvironment() {
        // We used the RealityKit Debugger to identify the names of things we want to hide in the club
        ["setDressing", "MovementBoundaries", "planter_side", "planter_Hero", "planter_Hero_1", "planter_Hero_2", "PlantLightGroup",
         "PlantLightGroup_1", "PlantLightGroup_2", "SidePlanterLights", "pipe_2", "pipe_3", "dirt_coffeeBerry_1", "dirt_coffeeBerry_2",
         "dirt_coffeeBerry_3", "dirt_side"].forEach { name in
            if let entity = rootEntity.findEntity(named: name) {
                entity.removeFromParent()
            }
        }
    }
    
    /// Repurpose some existing bits in the environment to create a makeshift revolving dance floor - if it looks like dirt, that's because it is
    private func addRevolvingDanceFloorToTheClub() {
        guard let dirtFloor = loadedEnvironmentRoot?.findEntity(named: "dirt_end") else {
            return
        }
        
        // Add a revolving container entity
        let revolvingDanceFloor = Entity()
        revolvingDanceFloor.name = "Revolving Dance Floor"
        revolvingDanceFloor.scale = [1, 1, 1]
        revolvingDanceFloor.position = [0, 0.181, 0]
        revolvingDanceFloor.components[RevolvingComponent.self] = RevolvingComponent(relativeTo: rootEntity)
        
        // Polish up the dirt floor
        let geometry = dirtFloor.clone(recursive: false)
        geometry.name = "Dirt Floor"
        geometry.transform = .identity
        geometry.position = [0, 0, 0]
        geometry.scale = dirtFloor.scale(relativeTo: rootEntity)
        
        let polish = geometry.clone(recursive: false)
        polish.name = "Polish Layer"
        polish.position = [0, 0.0004, 0]
        
        if var modelComponent = geometry.components[ModelComponent.self] {
            var polishedFloorMaterial = PhysicallyBasedMaterial()
            
            polishedFloorMaterial.baseColor = .init(tint: .gray)
            polishedFloorMaterial.roughness = .init(floatLiteral: 0.2)
            polishedFloorMaterial.metallic = .init(floatLiteral: 0.8)
            polishedFloorMaterial.blending = .transparent(opacity: .init(floatLiteral: 0.5))
            polishedFloorMaterial.clearcoat = .init(floatLiteral: 0.4)
            
            modelComponent.materials = [polishedFloorMaterial]
            
            polish.components[ModelComponent.self] = modelComponent
        }
        
        // Add it to the revolving container
        revolvingDanceFloor.addChild(geometry)
        revolvingDanceFloor.addChild(polish)
        
        rootEntity.addChild(revolvingDanceFloor)
    }
    
    /// Creates a revolving container entity to keep robots moving in sync with the dance floor
    private func addRobotRevolutionControllerToTheClub() {
        let robotRevolutionController = Entity()
        robotRevolutionController.name = "Robot Revolution Controller"
        robotRevolutionController.components[RevolvingComponent.self] = RevolvingComponent(relativeTo: rootEntity)
        
        rootEntity.addChild(robotRevolutionController)
        
        self.robotRevolutionController = robotRevolutionController
    }
    
    /// Add invisible attractors to the dance floor to position and control robots
    private func addDanceFloorAttractors() {
        guard let robotRevolutionController else {
            logger.error("The Robot Revolution Controller is missing 😱")
            return
        }
        
        // Add a few dance spots on the outside of the club that we know don't obstruct the furniture
        let staticAttractors = Entity()
        staticAttractors.name = "Static Attractors"
        
        let placementRadius: Float = 0.25
        let outerRadius = placementRadius * 0.8
        addDanceFloorAttractor(to: staticAttractors, angle: Angle2D(degrees: 10), placementRadius: outerRadius, name: "Static-A1", variation: 0)
        addDanceFloorAttractor(to: staticAttractors, angle: Angle2D(degrees: 90), placementRadius: outerRadius, name: "Static-A2", variation: 0)
        addDanceFloorAttractor(to: staticAttractors, angle: Angle2D(degrees: 130), placementRadius: outerRadius, name: "Static-A3", variation: 0)
        addDanceFloorAttractor(to: staticAttractors, angle: Angle2D(degrees: 240), placementRadius: outerRadius, name: "Static-A4", variation: 0)
        addDanceFloorAttractor(to: staticAttractors, angle: Angle2D(degrees: 325), placementRadius: outerRadius, name: "Static-A5", variation: 0)
        
        rootEntity.addChild(staticAttractors)
        
        // The remaining center attractors are on the revolving dance floor and can be more randomly positioned
        let innerRingCapacity = doorSupervisor.capacity - 5
        
        let revolvingAttractors = Entity()
        revolvingAttractors.name = "Revolving Attractors"
        
        addDanceFloorAttractors(to: revolvingAttractors, count: innerRingCapacity, placementRadius: placementRadius * 0.3, namePrefix: "Revolving")
        
        robotRevolutionController.addChild(revolvingAttractors)
        
#if DEBUG
        // Add some debug visualizations
        let debugRoot = Entity()
        debugRoot.name = "[Debug] Dance System"
        debugRoot.isEnabled = false
        debugRoot.components[DanceSystemDebugComponent.self] = DanceSystemDebugComponent()
        
        rootEntity.addChild(debugRoot)
        
        let allAttractors = Array(staticAttractors.children) + Array(revolvingAttractors.children)
        
        // Create a new visualization for each attractor
        allAttractors.forEach { attractor in
            if let visualization = Entity.makeDebugMarker(height: 0.08, radius: 0.03, enabled: true) {
                guard let attractorComponent = attractor.components[AttractorComponent.self] else {
                    return
                }
                
                let debugComponent = AttractorDebugComponent(state: attractorComponent.state, attractor: attractor)
                
                visualization.position = [0, 0.04, 0]
                visualization.components[AttractorDebugComponent.self] = debugComponent
                debugRoot.addChild(visualization)
            }
        }
#endif
    }
    
    /// Add multiple dance floor attractors along the circumference of a circle with the specified placementRadius
    private func addDanceFloorAttractors(to danceFloor: Entity, count: Int, placementRadius: Float, namePrefix: String, variation: Float = 0.005) {
        let angleIncrements = 360 / count
        
        for offset in 0..<count {
            let angle = Angle2D(degrees: Double(angleIncrements * offset))
            let name = "\(namePrefix)-A\(offset + 1)"
            addDanceFloorAttractor(to: danceFloor, angle: angle, placementRadius: placementRadius, name: name, variation: variation)
        }
    }
    
    /// Adds a single dance floor attractor at a point on the circumference of a circle with the specified placementRadius
    private func addDanceFloorAttractor(to danceFloor: Entity, angle: Angle2D, placementRadius: Float, name: String, variation: Float = 0.005) {
        let attractor = Entity()
        attractor.name = name
        attractor.components[AttractorComponent.self] = AttractorComponent(club: rootEntity)
        attractor.position = pointOnCircumference(angle: angle, radius: placementRadius, variation: variation)
        danceFloor.addChild(attractor)
    }
    
    /// Adds some revolving spot lights to the club
    private func addSpotlightsToTheClub() {
        let placementRadius: Float = 0.5
        let lightsWrapper = Entity()
        lightsWrapper.name = "Light Rig"
        
        let magentaLight = SpotLight()
        magentaLight.light.color = .magenta
        magentaLight.light.intensity = 500
        var lightPosition = pointOnCircumference(angle: Angle2D(degrees: 0), radius: placementRadius, y: 0.5)
        magentaLight.look(at: .zero, from: lightPosition, relativeTo: rootEntity)
        lightsWrapper.addChild(magentaLight)
        
        let greenLight = magentaLight.clone(recursive: true)
        greenLight.light.color = .green
        lightPosition = pointOnCircumference(angle: Angle2D(degrees: 120), radius: placementRadius, y: 0.5)
        greenLight.look(at: .zero, from: lightPosition, relativeTo: rootEntity)
        lightsWrapper.addChild(greenLight)
        
        let cyanLight = magentaLight.clone(recursive: true)
        cyanLight.light.color = .cyan
        lightPosition = pointOnCircumference(angle: Angle2D(degrees: 240), radius: placementRadius, y: 0.5)
        cyanLight.look(at: .zero, from: lightPosition, relativeTo: rootEntity)
        lightsWrapper.addChild(cyanLight)
        
        lightsWrapper.components[RevolvingComponent.self] = RevolvingComponent(speed: -0.2, relativeTo: rootEntity)
        
        rootEntity.addChild(lightsWrapper)
    }
    
    /// Repurpose some planters to make a counter and stocks with a premium aged oil, and a friendly host
    private func addCounterToTheClub() {
        guard let planter = rootEntity.findEntity(named: "planter_big"),
              let dirt = rootEntity.findEntity(named: "dirt_big") else {
            logger.error("Making the counter failed... too much dancing may now cause rust 🤖")
            return
        }
        
        // Group into a container entity
        let counter = Entity()
        counter.name = "Counter"
        counter.position = [0.333, 0.05, -0.09]
        rootEntity.addChild(counter)
        
        // Repurpose existing assets
        let counterGeometry = Entity()
        counterGeometry.name = "Counter Geometry"
        counterGeometry.addChild(planter, preservingWorldTransform: true)
        counterGeometry.addChild(dirt, preservingWorldTransform: true)
        counterGeometry.scale = [2, 6, 2]
        counterGeometry.position = [-0.3335, -0.15, 0.09]
        counter.addChild(counterGeometry)
        
        var counterTopMaterial = PhysicallyBasedMaterial()
        counterTopMaterial.baseColor = .init(tint: .white)
        counterTopMaterial.roughness = .init(floatLiteral: 0)
        counterTopMaterial.metallic = .init(floatLiteral: 1)
        
        dirt.components[ModelComponent.self]?.materials = [counterTopMaterial]
        dirt.position += [0, 0.001, 0]
        
        // Add a fancy hover rail
        if let rim = rootEntity.findEntity(named: "bottom_rim_1") {
            let hoverRailing = rim.clone(recursive: true)
            hoverRailing.name = "Hover Railing"
            hoverRailing.position = [0, 0.1, 0]
            hoverRailing.scale = rim.scale(relativeTo: rootEntity) * 0.5
            hoverRailing.components[HoverComponent.self] = HoverComponent(from: hoverRailing.position, to: hoverRailing.position + [0, -0.03, 0])
            counter.addChild(hoverRailing)
        }
        
        // Add some bottles to the counter
        let bottles = stockBottles(placementRadius: 0.045)
        counter.addChild(bottles)
        
        // Hide any out of stock items
        for bottle in bottles.children {
            bottle.isEnabled = bottle.components[OutOfStockComponent.self] == nil
        }
        
        // Add a friendly host
        addHostToTheCounter(counter)
    }
    
    /// Adds 9 green bottles of the finest aged oil to the counter (assuming we have them in stock)
    private func stockBottles(placementRadius: Float) -> Entity {
        let bottleRadius: Float = 0.003
        let bottleHeight: Float = 0.022
        let angleIncrement: Float = -12
        let outOfStockBrands: Set = [3]
        
        // Make a wrapper entity
        let bottleGroup = Entity()
        bottleGroup.name = "Bottle Group"
        bottleGroup.position = [0, 0.04, 0]
        bottleGroup.orientation = .init(angle: 180 * (.pi / 180), axis: [0, 1, 0])
        
        // Make a nice green material
        var bottleMaterial = PhysicallyBasedMaterial()
        bottleMaterial.baseColor = .init(tint: .green)
        bottleMaterial.blending = .transparent(opacity: .init(floatLiteral: 0.5))
        
        // A simple cylinder mesh
        let bottleMesh = MeshResource.generateCylinder(height: bottleHeight, radius: bottleRadius)
        
        // Error 1: Content occluded
        let bottle1 = Entity()
        bottle1.name = "BT1"
        bottle1.position = pointOnCircumference(angle: .zero, radius: placementRadius, y: -0.03)
        bottle1.components[ModelComponent.self] = ModelComponent(mesh: bottleMesh, materials: [bottleMaterial])
        bottleGroup.addChild(bottle1)
        
        // Error 2: Content clipped
        let bottle2 = Entity()
        bottle2.name = "BT2"
        bottle2.position = pointOnCircumference(angle: Angle2D(degrees: angleIncrement), radius: 1.6, y: bottleHeight / 2)
        bottle2.components[ModelComponent.self] = ModelComponent(mesh: bottleMesh, materials: [bottleMaterial])
        bottleGroup.addChild(bottle2)
        
        // Error 3: Content inside out
        let bottle3 = Entity()
        bottle3.name = "BT3"
        bottle3.position = pointOnCircumference(angle: Angle2D(degrees: 2 * angleIncrement), radius: placementRadius, y: bottleHeight / 2)
        bottle3.scale = .init(repeating: 650)
        bottle3.components[ModelComponent.self] = ModelComponent(mesh: bottleMesh, materials: [bottleMaterial])
        bottleGroup.addChild(bottle3)
        
        // Error 4: Content not enabled
        let bottle4 = Entity()
        bottle4.name = "BT4"
        bottle4.position = pointOnCircumference(angle: Angle2D(degrees: 3 * angleIncrement), radius: placementRadius, y: bottleHeight / 2)
        bottle4.components[ModelComponent.self] = ModelComponent(mesh: bottleMesh, materials: [bottleMaterial])
        bottle4.components[OutOfStockComponent.self] = OutOfStockComponent()
        bottleGroup.addChild(bottle4)
        
        // Error 5: Content not anchored
        let bottle5 = Entity()
        bottle5.name = "BT5"
        bottle5.position = pointOnCircumference(angle: Angle2D(degrees: 4 * angleIncrement), radius: placementRadius, y: bottleHeight / 2)
        bottle5.components[AnchoringComponent.self] = AnchoringComponent(.plane(.horizontal, classification: .table, minimumBounds: .zero))
        bottle5.components[ModelComponent.self] = ModelComponent(mesh: bottleMesh, materials: [bottleMaterial])
        bottleGroup.addChild(bottle5)
        
        // Error 6: Content missing a mesh
        let bottle6 = Entity()
        bottle6.name = "BT6"
        bottle6.position = pointOnCircumference(angle: Angle2D(degrees: 5 * angleIncrement), radius: placementRadius, y: bottleHeight / 2)
        bottle5.components[ModelComponent.self] = ModelComponent(mesh: bottleMesh, materials: [bottleMaterial])
        bottleGroup.addChild(bottle6)
        
        // Error 7: Content's material misconfigured
        let bottle7 = Entity()
        bottle7.name = "BT7"
        bottle7.position = pointOnCircumference(angle: Angle2D(degrees: 6 * angleIncrement), radius: placementRadius, y: bottleHeight / 2)
        
        var simplifiedBottleMaterial = UnlitMaterial(color: .green.withAlphaComponent(0.5))
        simplifiedBottleMaterial.opacityThreshold = 1
        
        bottle7.components[ModelComponent.self] = ModelComponent(mesh: bottleMesh, materials: [simplifiedBottleMaterial])
        bottleGroup.addChild(bottle7)
        
        // Error 8: Content has a broken mesh
        let alternativeMesh = MeshResource.generateAbnormalCylinder(height: bottleHeight, radius: bottleRadius)
        let bottle8 = Entity()
        bottle8.name = "BT8"
        bottle8.position = pointOnCircumference(angle: Angle2D(degrees: 7 * angleIncrement), radius: placementRadius, y: bottleHeight / 2)
        bottle8.scale = [bottle8.scale.x, bottle8.scale.y, -bottle8.scale.z]
        bottleMaterial.opacityThreshold = 0
        bottle8.components[ModelComponent.self] = ModelComponent(mesh: alternativeMesh, materials: [bottleMaterial])
        bottleGroup.addChild(bottle8)
        
        // Error 9: Content not added to the scene hierarchy
        let bottle9 = Entity()
        bottle9.name = "BT9"
        bottle9.position = pointOnCircumference(angle: Angle2D(degrees: 8 * angleIncrement), radius: placementRadius, y: bottleHeight / 2)
        bottle9.components[ModelComponent.self] = ModelComponent(mesh: bottleMesh, materials: [bottleMaterial])
        bottleGroup.addChild(bottle8)
        
        // FIXME: Bottles are missing from the counter
        
        return bottleGroup
    }
    
    /// Add a host robot to the counter
    private func addHostToTheCounter(_ counter: Entity) {
        // Make a clone of our hero BOTanist
        let robotMaker = AppState()
        
        guard let skeleton = robotMaker.robotData.meshes[.body]?.findEntity(named: "rig_grp") as? ModelEntity else {
            fatalError()
        }
        
        // But use the hover body to best complement the counter
        robotMaker.setMesh(part: .body, name: "body3")
        
        guard let head = robotMaker.robotData.meshes[.head]?.clone(recursive: true),
              let body = robotMaker.robotData.meshes[.body]?.clone(recursive: true),
              let backpack = robotMaker.robotData.meshes[.backpack]?.clone(recursive: true) else {
            fatalError()
        }
        
        let robotCharacter = RobotCharacter(
            head: head,
            body: body,
            backpack: backpack,
            appState: robotMaker,
            headOffset: skeleton.pins["head"]?.position,
            backpackOffset: skeleton.pins["backpack"]?.position
        )
        
        // Remove the character controller and animation state, as we'll manually control these
        AnimationState.handlers.removeAll()
        robotCharacter.characterParent.components[CharacterControllerComponent.self] = nil
        
        // Take off that heavy backpack
        backpack.removeFromParent()
        
        // Setup our host using the character and add it to the counter
        let host = Entity()
        host.name = "Host"
        host.orientation = .init(angle: 300 * (.pi / 180), axis: [0, 1, 0])
        host.position = [0, 0.005, 0]
        host.components[AutomatonControl.self] = AutomatonControl(character: robotCharacter)
        host.addChild(robotCharacter.characterParent)
        counter.addChild(host)
        
        // Have them say Hi
        robotCharacter.transitionToAndPlayAnimation(.wave)
        
        // Save a reference so they can wave later when other bots enter
        self.host = host
    }
    
    /// Generates a disco ball looking entity, makes it revolve and hover, and adds it to the club
    private func addDiscoBallToTheClub() {
        // Add the top level revolving, hovering disco ball entity
        let discoBall = Entity()
        discoBall.name = "Disco Ball"
        discoBall.position = [-0.305, 0.17, 0.02]
        discoBall.components[RevolvingComponent.self] = RevolvingComponent(speed: -0.02, relativeTo: rootEntity)
        discoBall.components[HoverComponent.self] = HoverComponent(from: discoBall.position, to: discoBall.position + [0, 0.02, 0])
        
        rootEntity.addChild(discoBall)
        
        // Add a support beam to hold the disco ball
        var supportMaterial = PhysicallyBasedMaterial()
        supportMaterial.baseColor = .init(tint: .lightGray)
        supportMaterial.roughness = .init(floatLiteral: 0.8)
        supportMaterial.metallic = .init(floatLiteral: 0.8)
        
        let support = ModelEntity(mesh: .generateCylinder(height: 0.01, radius: 0.01), materials: [supportMaterial])
        support.scale = [0.2, 1.8, 0.2]
        support.position = [0, 0.05, 0]
        support.name = "Support"
        
        discoBall.addChild(support)
        
        // Add the shiny ball that is the base of our disco ball
        var backgroundMaterial = PhysicallyBasedMaterial()
        backgroundMaterial.baseColor = .init(tint: .lightGray)
        backgroundMaterial.roughness = .init(floatLiteral: 0)
        backgroundMaterial.metallic = .init(floatLiteral: 1)
        
        let background = ModelEntity(mesh: .generateSphere(radius: 0.05), materials: [backgroundMaterial])
        background.name = "Background"
        
        // FIXME: Unintentionally inheriting an ancestor's transformation
        support.addChild(background)
        
        // Add some detailed lines on top of the background
        var lineMaterial = PhysicallyBasedMaterial()
        lineMaterial.baseColor = .init(tint: .lightGray)
        lineMaterial.sheen = .init(tint: .lightGray)
        lineMaterial.emissiveColor = .init(color: .lightGray)
        lineMaterial.emissiveIntensity = 1
        lineMaterial.triangleFillMode = .lines
        
        let ballOutline = ModelEntity(mesh: .generateSphere(radius: 0.0505), materials: [lineMaterial])
        ballOutline.name = "Outline"
        
        background.addChild(ballOutline)
    }
    
    /// Marks the club as ready
    private func openDoors() {
        var management = self.doorSupervisor
        management.doorsOpen = true
        self.doorSupervisor = management
    }
    
    /// finds a point along the edge of a circle on an XZ-plane, given a radius and y value. Optionally applies some variance.
    private func pointOnCircumference(angle: Angle2D, radius: Float, variation: Float = 0, y: Float = 0) -> SIMD3<Float> {
        .init(
            x: (Float(cos(angle)) * radius) + .random(in: -variation...variation),
            y: y,
            z: (Float(sin(angle)) * radius) + .random(in: -variation...variation)
        )
    }
}

// MARK: Club Management

/// Manages club capacity and ready state
struct DoorSupervisor: Component {
    let capacity: Int
    var doorsOpen = false
    var visitorCount = 0
    
    var hasCapacity: Bool {
        visitorCount < capacity
    }
}

/// Tag to indicate if a retail item is in stock
struct OutOfStockComponent: Component {}

// MARK: Revolution Control

/// Works with the RevolvingSystem to apply a continuous rotation to an entity
struct RevolvingComponent: Component {
    var speed: Float
    var angle: Float
    var axis: SIMD3<Float>
    var relativeTo: Entity?
    
    init(speed: Float = 0.05, initialAngle: Float = 0, axis: SIMD3<Float> = [0, 1, 0], relativeTo: Entity? = nil) {
        self.speed = speed
        self.angle = initialAngle
        self.axis = axis
        self.relativeTo = relativeTo
    }
}

/// Works with the RevolvingComponent to apply a continuous rotation to an entity
@MainActor
class RevolvingSystem: System {
    private static let query = EntityQuery(where: .has(RevolvingComponent.self))
    
    required init(scene: RealityKit.Scene) {}
    
    func update(context: SceneUpdateContext) {
        for entity in context.entities(matching: Self.query, updatingSystemWhen: .rendering) {
            if var revolvingComponent = entity.components[RevolvingComponent.self] {
                let relativeTo = revolvingComponent.relativeTo
                
                revolvingComponent.angle += .pi * Float(context.deltaTime) * revolvingComponent.speed
                entity.setOrientation(.init(angle: revolvingComponent.angle, axis: revolvingComponent.axis), relativeTo: relativeTo)
                
                entity.components[RevolvingComponent.self] = revolvingComponent
            }
        }
    }
}

// MARK: Hover Control

/// Works with the HoverSystem to apply a continuous levitation like bounce to an entity
struct HoverComponent: Component {
    var speed: Float
    var angle: Float
    var from: SIMD3<Float>
    var to: SIMD3<Float>
    
    init(speed: Float = 0.06, angle: Float = 0, from: SIMD3<Float>, to: SIMD3<Float>) {
        self.speed = speed
        self.angle = angle
        self.from = from
        self.to = to
    }
}

/// Works with the HoverComponent to apply a continuous levitation like bounce to an entity
@MainActor
class HoverSystem: System {
    private static let query = EntityQuery(where: .has(HoverComponent.self))
    
    required init(scene: RealityKit.Scene) {}
    
    func update(context: SceneUpdateContext) {
        for entity in context.entities(matching: Self.query, updatingSystemWhen: .rendering) {
            if var hoverComponent = entity.components[HoverComponent.self] {
                
                hoverComponent.angle += .pi * Float(context.deltaTime) * hoverComponent.speed
                
                let range = hoverComponent.to - hoverComponent.from
                let proportion = (sin(hoverComponent.angle) + 1) / 2
                
                entity.position = hoverComponent.from + (proportion * range)
                
                entity.components[HoverComponent.self] = hoverComponent
            }
        }
    }
}

// MARK: Robot Parts

/// A wrapper around a Robot Character that is actually used as an Automaton
struct AutomatonControl: Component {
    var character: RobotCharacter
}

extension RobotCharacter {
    /// manually control the animation transition of a single robot instance
    func transitionToAndPlayAnimation(_ animationState: AnimationState) {
        if self.animationState.transition(to: animationState) {
            playAnimation(animationState)
        }
    }
}

/// A collection of shuffled robot names for our Automatons
@MainActor
enum RobotNames {
    static var count: Int = 0
    static var next: String {
        count += 1
        
        return "Robo-v\(count)"
    }
}

// MARK: Teleportation

/// Works with the TeleportationSystem to control spawning across all teleporters
struct ControlCenterComponent: Component {
    typealias SpawnHandler = (Entity) -> Void
    
    var initialValue: TimeInterval
    var interval: TimeInterval
    var countdown: TimeInterval
    var rootEntity: Entity
    var _spawnHandler: SpawnHandler
    
    init(initialValue: TimeInterval, interval: TimeInterval, rootEntity: Entity, spawnHandler: @escaping SpawnHandler) {
        self.initialValue = initialValue
        self.interval = interval
        self.countdown = initialValue
        self.rootEntity = rootEntity
        self._spawnHandler = spawnHandler
    }
}

/// Represents a single Teleporter in the TeleportationSystem
struct TeleporterComponent: Component {}

/// Works with the ControlCenterComponent to control spawning across all teleporters
@MainActor
class TeleportationSystem: System {
    private static let controlCenterQuery = EntityQuery(where: .has(ControlCenterComponent.self))
    private static let teleporterQuery = EntityQuery(where: .has(TeleporterComponent.self))
    private static let robotQuery = EntityQuery(where: .has(AutomatonControl.self))
    
    required init(scene: RealityKit.Scene) {}
    
    func update(context: SceneUpdateContext) {
        for entity in context.entities(matching: Self.controlCenterQuery, updatingSystemWhen: .rendering) {
            update(controlCenter: entity, context: context)
        }
    }
    
    private func safeToUse(teleporter: Entity, context: SceneUpdateContext) -> Bool {
        let someBotIsStandingToClose = context.entities(matching: Self.robotQuery, updatingSystemWhen: .rendering)
            .contains { entity in
                distance(entity.position(relativeTo: nil), teleporter.position(relativeTo: nil)) < 0.02
            }
        
        return  !someBotIsStandingToClose
    }
    
    private func update(controlCenter controlCenterEntity: Entity, context: SceneUpdateContext) {
        guard var controlCenter = controlCenterEntity.components[ControlCenterComponent.self],
              let clubManager = controlCenter.rootEntity.components[DoorSupervisor.self],
              clubManager.hasCapacity else {
            return
        }
        
        // 1. Decrease countdown, and activate if it reaches zero
        controlCenter.countdown -= context.deltaTime
        if controlCenter.countdown <= 0 {
            
            // 2. Find all the active teleporters and pick a random one
            if let teleporter = context.entities(matching: Self.teleporterQuery, updatingSystemWhen: .rendering).shuffled().first {
                
                // 3. If no other robots are in the way, pass it to the designated spawn method
                if safeToUse(teleporter: teleporter, context: context) {
                    controlCenter._spawnHandler(teleporter)
                }
            }
            
            // 4. Set the delay till the next spawn event
            controlCenter.countdown = controlCenter.interval
        }
        
        // FIXME: Control Center is not being updated
    }
}

extension ParticleEmitterComponent.Presets {
    /// Makes a particle emitter component that looks like a teleporter
    fileprivate static var teleporter: ParticleEmitterComponent {
        var particleEmitter = ParticleEmitterComponent.Presets.rain
        
        particleEmitter.birthLocation = .surface
        particleEmitter.emitterShape = .torus
        particleEmitter.particlesInheritTransform = false
        particleEmitter.fieldSimulationSpace = .global
        particleEmitter.speed = 0.07
        particleEmitter.speedVariation = 0.03
        particleEmitter.radialAmount = 360
        particleEmitter.torusInnerRadius = 0.001
        particleEmitter.emissionDirection = [0, 1, 0]
        particleEmitter.spawnedEmitter = nil
        particleEmitter.burstCount = 5000
        particleEmitter.mainEmitter.opacityCurve = .linearFadeOut
        particleEmitter.mainEmitter.birthRate = 50
        particleEmitter.mainEmitter.birthRateVariation = 10
        particleEmitter.mainEmitter.lifeSpan = 0.5
        particleEmitter.mainEmitter.lifeSpanVariation = 0.01
        particleEmitter.mainEmitter.size = 0.001
        particleEmitter.mainEmitter.sizeVariation = 0.0005
        particleEmitter.mainEmitter.sizeMultiplierAtEndOfLifespan = 0.01
        particleEmitter.mainEmitter.stretchFactor = 10
        particleEmitter.mainEmitter.noiseStrength = 0
        particleEmitter.mainEmitter.spreadingAngle = 0
        particleEmitter.mainEmitter.angle = 0
        
        particleEmitter.spawnedEmitter = nil
        
        return particleEmitter
    }
}

// MARK: Dancing

/// Represents a single Attractor in the DanceMotivationSystem
struct AttractorComponent: Component {
    enum State {
        case vacant
        case attracting
        case motivating
    }
    
    private(set) var state: State = .vacant
    
    var target: Entity?
    var walkSpeed: Float = 0.1
    var interval: TimeInterval = 5
    var countdown: TimeInterval = 5
    var club: Entity?
    
    var isVacant: Bool {
        if case .vacant = state {
            return true
        }
        return false
    }
    
    mutating func setTarget(_ target: Entity) {
        self.target = target
        self.state = .attracting
    }
    
    mutating func targetReached() {
        self.state = .motivating
    }
}

/// Represents a single Robot in the DanceMotivationSystem
struct Newcomer: Component {}

/// Works with the DanceMotivationSystem to provide additional Debug information to the RealityKit Debugger
struct DanceSystemDebugComponent: Component {
    var states: UIImage? = nil
    var vacant: Int = 0
    var attracting: Int = 0
    var motivating: Int = 0
}

/// Provides additional Debug information about a single Attractor in the DanceMotivationSystem to the RealityKit Debugger
struct AttractorDebugComponent: Component {
    var state: AttractorComponent.State
    var attractor: Entity
    var robot: Entity?
}

/// Manages the states of dance floor attractors, the movement of robots and the relationships between them
@MainActor
class DanceMotivationSystem: System {
    private static let attractorQuery = EntityQuery(where: .has(AttractorComponent.self))
    private static let targetQuery = EntityQuery(where: .has(Newcomer.self))
    private static let clubbersQuery = EntityQuery(where: .has(AutomatonControl.self))
    private static let debugRootQuery = EntityQuery(where: .has(DanceSystemDebugComponent.self))
    private static let debugVisualizationsQuery = EntityQuery(where: .has(AttractorDebugComponent.self))
    
    required init(scene: RealityKit.Scene) {}
    
    func update(context: SceneUpdateContext) {
        
        // 1. Check for newcomers at the club who could be enticed to come and dance
        for visitor in context.entities(matching: Self.targetQuery, updatingSystemWhen: .rendering) {
            
            // 2. Randomly pick an attractor
            guard let attractor = context.entities(matching: Self.attractorQuery, updatingSystemWhen: .rendering)
                .filter({ $0.components[AttractorComponent.self]?.isVacant ?? false })
                .randomElement() else {
                return
            }
            
            // 3. Start attracting the visitor
            var attractorComponent = attractor.components[AttractorComponent.self]!
            attractorComponent.setTarget(visitor)
            attractor.components[AttractorComponent.self] = attractorComponent
            
            // FIXME: Stop attractors competing over the same bot
        }
        
        // Let the attractors do their thing and attract visitors to come and dance
        for attractor in context.entities(matching: Self.attractorQuery, updatingSystemWhen: .rendering) {
            guard var attractorComponent = attractor.components[AttractorComponent.self] else {
                continue
            }
            
            switch attractorComponent.state {
            case .attracting:
                if let updatedAttractorComponent = attractRobot(attractor: attractor, deltaTime: Float(context.deltaTime)) {
                    attractorComponent = updatedAttractorComponent
                }
                
            case .motivating:
                if let updatedAttractorComponent = motivateRobot(attractor: attractor, context: context) {
                    attractorComponent = updatedAttractorComponent
                }
                
            default:
                break
            }
            
            // save changes
            attractor.components[AttractorComponent.self] = attractorComponent
        }
        
#if DEBUG
        updateDebugInfo(context: context)
#endif
    }
    
    private func attractRobot(attractor: Entity, deltaTime: Float) -> AttractorComponent? {
        guard var attractorComponent = attractor.components[AttractorComponent.self],
              case .attracting = attractorComponent.state,
              let target = attractorComponent.target,
              let robotCharacter = target.components[AutomatonControl.self]?.character else {
            return nil
        }
        
        // robots wave when they first arrive, make sure that is completed first before moving
        var transitionAnimationTo: AnimationState?
        switch robotCharacter.animationState {
        case .wave: transitionAnimationTo = .idle
        case .idle: transitionAnimationTo = .walkLoop
        case .walkLoop: transitionAnimationTo = nil
        default: return attractorComponent
        }
        
        if let transitionAnimationTo {
            if robotCharacter.animationState.transition(to: transitionAnimationTo) {
                robotCharacter.playAnimation(robotCharacter.animationState)
            }
        }
        
        // Convert the robot and target positions into the same coordinate system
        let targetPosition = target.position(relativeTo: attractorComponent.club)
        var danceSpotPosition = attractor.position(relativeTo: attractorComponent.club)
        danceSpotPosition.y = targetPosition.y
        
        let movementVector = danceSpotPosition - targetPosition
        let normalizedMovement = movementVector / length(movementVector)
        let move = normalizedMovement * deltaTime * attractorComponent.walkSpeed
        
        target.setPosition(targetPosition + move, relativeTo: attractorComponent.club)
        
        robotCharacter.characterModel.look(at: robotCharacter.characterModel.position - normalizedMovement,
                                           from: robotCharacter.characterModel.position, relativeTo: robotCharacter.characterParent)
        
        // If the target is more or less in position then attach to the dance spot and change state to motivating
        if distance(danceSpotPosition, target.position(relativeTo: attractorComponent.club)) < 0.005 {
            attractor.addChild(target, preservingWorldTransform: true)
            
            // Start Dancing
            robotCharacter.transitionToAndPlayAnimation(.celebrate)
            
            // Update attractor state
            attractorComponent.targetReached()
        }
        
        return attractorComponent
    }
    
    private func motivateRobot(attractor: Entity, context: SceneUpdateContext) -> AttractorComponent? {
        guard var attractorComponent = attractor.components[AttractorComponent.self],
              case .motivating = attractorComponent.state,
              let target = attractorComponent.target,
              let robotCharacter = target.components[AutomatonControl.self]?.character else {
            return nil
        }
        
        attractorComponent.countdown -= context.deltaTime
        
        if attractorComponent.countdown <= 0 {
            // Turn to face a random fellow clubber
            if let friend = Array(context.entities(matching: Self.clubbersQuery, updatingSystemWhen: .rendering)).randomElement() {
                let friendsPosition = friend.position(relativeTo: robotCharacter.characterParent)
                
                robotCharacter.characterModel.look(at: friendsPosition,
                                                   from: robotCharacter.characterModel.position, relativeTo: robotCharacter.characterParent)
                
                // TODO: remove me
                print("🔥 friendsPosition \(friendsPosition) targetPosition \(robotCharacter.characterModel.position)")
            }
            
            attractorComponent.countdown = attractorComponent.interval
        }
        
        return attractorComponent
    }
    
#if DEBUG
    let vacantColor = UnlitMaterial.BaseColor(tint: .yellow.withAlphaComponent(0.5))
    let attractingColor = UnlitMaterial.BaseColor(tint: .orange.withAlphaComponent(0.5))
    let motivatingColor = UnlitMaterial.BaseColor(tint: .red.withAlphaComponent(0.5))
    
    private func updateDebugInfo(context: SceneUpdateContext) {
        var vacantCount: Int = 0
        var attractingCount: Int = 0
        var motivatingCount: Int = 0
        
        context.entities(matching: Self.debugVisualizationsQuery, updatingSystemWhen: .rendering).forEach { visualization in
            guard let visualizationComponent = visualization.components[AttractorDebugComponent.self],
                  let attractorComponent = visualizationComponent.attractor.components[AttractorComponent.self] else {
                return
            }
            
            updateVisualizationEntity(visualization, relativeTo: attractorComponent.club)
            
            switch attractorComponent.state {
            case .vacant: vacantCount += 1
            case .attracting: attractingCount += 1
            case .motivating: motivatingCount += 1
            }
        }
        
        context.entities(matching: Self.debugRootQuery, updatingSystemWhen: .rendering).forEach { debugRoot in
            if var debugComponent = debugRoot.components[DanceSystemDebugComponent.self] {
                debugComponent.vacant = vacantCount
                debugComponent.attracting = attractingCount
                debugComponent.motivating = motivatingCount
                debugComponent.states = makeChart(vacantCount: vacantCount, attractingCount: attractingCount, motivatingCount: motivatingCount)
                debugRoot.components[DanceSystemDebugComponent.self] = debugComponent
            }
        }
    }
    
    private func updateVisualizationEntity(_ visualization: Entity, relativeTo root: Entity?) {
        guard var visualizationComponent = visualization.components[AttractorDebugComponent.self],
              let attractorComponent = visualizationComponent.attractor.components[AttractorComponent.self] else {
            return
        }
        
        // Update the position
        var position = visualizationComponent.attractor.position(relativeTo: root)
        position.y = visualization.position.y
        visualization.setPosition(position, relativeTo: root)
        
        // Update the state
        visualizationComponent.state = attractorComponent.state
        visualization.name = "[Debug] \(visualizationComponent.attractor.name) (\(attractorComponent.state))"
        
        // Update the base material color to signify the attractor state
        if var modelComponent = visualization.components[ModelComponent.self],
           var material = modelComponent.materials.first as? UnlitMaterial {
            
            switch attractorComponent.state {
            case .vacant: material.color = vacantColor
            case .attracting: material.color = attractingColor
            case .motivating: material.color = motivatingColor
            }
            
            modelComponent.materials = [material]
            visualization.components[ModelComponent.self] = modelComponent
        }
        
        // Update the target
        visualizationComponent.robot = attractorComponent.target
        visualization.components[AttractorDebugComponent.self] = visualizationComponent
    }
    
    private func makeChart(vacantCount: Int, attractingCount: Int, motivatingCount: Int) -> UIImage? {
        ImageRenderer(content: chartView(vacantCount: vacantCount, attractingCount: attractingCount, motivatingCount: motivatingCount)).uiImage
    }
    
    private func chartView(vacantCount: Int, attractingCount: Int, motivatingCount: Int) -> some View {
        Chart(
            [
                (name: "Vacant", count: vacantCount),
                (name: "Attracting", count: attractingCount),
                (name: "Motivating", count: motivatingCount)
            ], id: \.name) { name, count in
                SectorMark(
                    angle: .value("Value", count),
                    angularInset: 1.5
                )
                .cornerRadius(5)
                .foregroundStyle(by: .value("Name", name))
        }
        .chartLegend(.hidden)
        .chartForegroundStyleScale(["Vacant": .yellow, "Attracting": .orange, "Motivating": .red])
        .frame(width: 1024, height: 1024)
    }
    
#endif
}

// MARK: Debug Helpers

extension Entity {
    /// creates an semi-transparent entity that can be useful in debug invisible entities in the RealityKit Debugger
    static func makeDebugMarker(name: String? = nil, height: Float, radius: Float, color: UIColor = .white, enabled: Bool = false) -> Entity? {
#if DEBUG
        var debugMaterial = UnlitMaterial()
        debugMaterial.color = .init(tint: color)
        debugMaterial.blending = .transparent(opacity: 0.7)
        
        let marker = ModelEntity(mesh: .generateCylinder(height: height, radius: radius), materials: [debugMaterial])
        if let name {
            marker.name = name
        }
        marker.isEnabled = enabled
        
        return marker
#else
        return nil
#endif
    }
    
    /// adds an semi-transparent child entity that can be useful in debug invisible entities in the RealityKit Debugger
    @discardableResult
    func addDebugMarker(name: String? = nil, height: Float? = nil, radius: Float? = nil, color: UIColor = .white, enabled: Bool = false) -> Entity? {
#if DEBUG
        var markerRadius: Float
        if radius != nil {
            markerRadius = radius!
        } else {
            // If no provided radius then calculate from the visual bounds
            let extents = visualBounds(relativeTo: nil).extents
            let boundingXZRadius = max(extents.x, extents.z) / 2
            
            if boundingXZRadius.isNormal {
                markerRadius = boundingXZRadius
            } else {
                // If no visual bounds then use a default radius of 1cm
                markerRadius = 0.01 * scale(relativeTo: nil).max()
            }
        }
        
        // If no provided height then use a default value of 10cm
        let markerHeight = height ?? 0.1 * scale(relativeTo: nil).max()
        
        let name = name ?? "[Debug] \(self.name)"
        if let marker = Entity.makeDebugMarker(name: name, height: markerHeight, radius: markerRadius, color: color, enabled: enabled) {
            marker.position = [0, markerHeight / 2, 0]
            addChild(marker)
            
            return marker
        }
#endif
        return nil
    }
}

// MARK: Demo Helpers

extension MeshResource {
    /// Generates an cylinder with all the normals facing downwards. Probably has no uses other than demo'ing a broken mesh.
    static func generateAbnormalCylinder(height: Float, radius: Float) -> MeshResource {
        let meshResource = MeshResource.generateCylinder(height: height, radius: radius)
        var contents = meshResource.contents
        let models = contents.models.map { model in
            var model = model
            let parts = model.parts.map { part in
                var part = part
                part.normals = part.normals.map { normals in
                    let transformedNormals: [SIMD3<Float>] = normals.map { _ in
                        [0, -1, 0]
                    }
                    
                    return MeshBuffer(transformedNormals)
                }
                
                return part
            }
            model.parts = MeshPartCollection(parts)
            
            return model
        }
        contents.models = MeshModelCollection(models)
        try? meshResource.replace(with: contents)
        
        return meshResource
    }
}

3:02 - Add a volumetric club scene

WindowGroup(id: "RobotClub") {
    GeometryReader3D { geometry in
        ClubView()
            .volumeBaseplateVisibility(.visible)
            .environment(appState)
            .scaleEffect(geometry.size.width / initialVolumeSize.width)
    }
    .onAppear {
        dismissWindow(id: "RobotCreation")
    }
}
.windowStyle(.volumetric)
.defaultWorldScaling(.dynamic)
.defaultSize(initialVolumeSize)

3:09 - Add a button to open the club

VStack {
    Button("🪩") {
        openWindow(id: "RobotClub")
    }
    .padding()

    Spacer()
}
.padding([.trailing, .top])

6:50 - FIX: Unintentionally inheriting an ancestor's transformation

discoBall.addChild(background)

10:18 - FIX: Control Center is not being updated

// 5. Save updated component back to the entity
controlCenterEntity.components[ControlCenterComponent.self] = controlCenter

18:15 - FIX: Stocking bottles

private func stockBottles(placementRadius: Float) -> Entity {
    let bottleRadius: Float = 0.003
    let bottleHeight: Float = 0.022
    let angleIncrement: Float = -12
    let outOfStockBrands: Set = [3]
    
    // Make a wrapper entity
    let bottleGroup = Entity()
    bottleGroup.name = "Bottle Group"
    bottleGroup.position = [0, 0.04, 0]
    bottleGroup.orientation = .init(angle: 180 * (.pi / 180), axis: [0, 1, 0])
    
    // Make a nice green material
    var bottleMaterial = PhysicallyBasedMaterial()
    bottleMaterial.baseColor = .init(tint: .green)
    bottleMaterial.blending = .transparent(opacity: .init(floatLiteral: 0.5))
    
    for i in 0..<9 {
        let angle = Angle2D(degrees: angleIncrement * Float(i))
        let bottleMesh = MeshResource.generateCylinder(height: bottleHeight, radius: bottleRadius)
        let bottle = ModelEntity(mesh: bottleMesh, materials: [bottleMaterial])
        bottle.name = "BT\(i)"
        bottle.position = pointOnCircumference(angle: angle, radius: placementRadius, y: bottleHeight / 2)
        if outOfStockBrands.contains(i) {
            bottle.components[OutOfStockComponent.self] = OutOfStockComponent()
        }
        
        bottleGroup.addChild(bottle)
    }
    
    return bottleGroup
}

22:48 - FIX: Attractors

// 4. Untag them as a Newcomer
visitor.components[Newcomer.self] = nil