RealityKitを使用した空間体験の構築

3:40 - Model3D

import SwiftUI
import RealityKit

struct GlobeModule: View {
    var body: some View {
        Model3D(named: "Globe") { model in
            model
                .resizable()
                .scaledToFit()
        } placeholder: {
          	ProgressView()
        }
    }
}

5:52 - Volumetric window

import SwiftUI
import RealityKit

// Define a volumetric window.
struct WorldApp: App {
    var body: some SwiftUI.Scene {
        // ...

        WindowGroup(id: "planet-earth") {
            Model3D(named: "Globe")
        }
        .windowStyle(.volumetric)
        .defaultSize(width: 0.8, height: 0.8, depth: 0.8, in: .meters)
    }
}

7:31 - ImmersiveSpace

import SwiftUI
import RealityKit

// Define a immersive space.
struct WorldApp: App {
    var body: some SwiftUI.Scene {
        // ...

        ImmersiveSpace(id: "objects-in-orbit") {
            RealityView { content in
                // ...
            }
        }
    }
}

12:40 - RealityView

import SwiftUI
import RealityKit

struct Orbit: View {
    let earth: Entity

    var body: some View {
        RealityView { content in
            content.add(earth)
        }
    }
}

12:54 - RealityView asynchronous loading and entity positioning

import SwiftUI
import RealityKit

struct Orbit: View {
    var body: some View {
        RealityView { content in
            async let earth = ModelEntity(named: "Earth")
            async let moon = ModelEntity(named: "Moon")

            if let earth = try? await earth, let moon = try? await moon {
                content.add(earth)
                content.add(moon)
                moon.position = [0.5, 0, 0]
            }
        }
    }
}

13:54 - Earth rotation

import SwiftUI
import RealityKit

struct RotatedModel: View {
    var entity: Entity
    var rotation: Rotation3D

    var body: some View {
        RealityView { content in
            content.add(entity)
        } update: { content in
            entity.orientation = .init(rotation)
        }
   }
}

14:27 - Converting co-ordinate spaces

import SwiftUI
import RealityKit

struct ResizableModel: View {
    var body: some View {
        GeometryReader3D { geometry in
            RealityView { content in
                if let earth = try? await ModelEntity(named: "Earth") {
                    let bounds = content.convert(geometry.frame(in: .local),
                                                 from: .local, to: content)
                    let minExtent = bounds.extents.min()
                    earth.scale = [minExtent, minExtent, minExtent]
                }
            }
        }
    }
}

14:56 - Play an animation

import SwiftUI
import RealityKit

struct AnimatedModel: View {
    @State var subscription: EventSubscription? 

    var body: some View {
        RealityView { content in
            if let moon = try? await Entity(named: "Moon"),
               let animation = moon.availableAnimations.first {
                moon.playAnimation(animation)
                content.add(moon)
            }
            subscription = content.subscribe(to: AnimationEvents.PlaybackCompleted.self) {
                // ...
            }
       }
   }
}

18:31 - Adding a drag gesture

import SwiftUI
import RealityKit

struct DraggableModel: View {
    var earth: Entity

    var body: some View {
        RealityView { content in
            content.add(earth)
        }
        .gesture(DragGesture()
            .targetedToEntity(earth)
            .onChanged { value in
                earth.position = value.convert(value.location3D,
                                               from: .local, to: earth.parent!)
            })
    }
}

20:20 - Playing a transform animation

// Playing a transform animation
let orbit = OrbitAnimation(name: "Orbit",
                           duration: 30,
                           axis: [0, 1, 0],
                           startTransform: moon.transform,
                           bindTarget: .transform,
                           repeatMode: .repeat)

if let animation = try? AnimationResource.generate(with: orbit) {
    moon.playAnimation(animation)
}

22:12 - Adding audio

// Create an empty entity to act as an audio source.
let audioSource = Entity()

// Configure the audio source to project sound out in a tight beam.
audioSource.spatialAudio = SpatialAudioComponent(directivity: .beam(focus: 0.75))

// Change the orientation of the audio source (rotate 180º around the Y axis).
audioSource.orientation = .init(angle: .pi, axis: [0, 1, 0])

// Add the audio source to a parent entity, and play a looping sound on it.
if let audio = try? await AudioFileResource(named: "SatelliteLoop",
                                            configuration: .init(shouldLoop: true)) {
    satellite.addChild(audioSource)
    audioSource.playAudio(audio)
}

23:47 - Defining a custom component

import RealityKit

// Components are data attached to an Entity.
struct TraceComponent: Component {
    var mesh = TraceMesh()
}

// Entities contain components, identified by the component’s type.
func updateTrace(for entity: Entity) {
    var component = entity.components[TraceComponent.self] ?? TraceComponent()
    component.update()
    entity.components[TraceComponent.self] = component
}

// Codable components can be added to entities in Reality Composer Pro.
struct PointOfInterestComponent: Component, Codable {
    var name = ""
}

24:51 - Defining a system

import SwiftUI
import RealityKit

// Systems supply logic and behavior.
struct TraceSystem: System {
    static let query = EntityQuery(where: .has(TraceComponent.self))
    
    init(scene: Scene) {
        // ...
    }

    func update(context: SceneUpdateContext) {
         // Systems often act on all entities matching certain conditions.
        for entity in context.entities(Self.query, updatingSystemWhen: .rendering) {
            addCurrentPositionToTrace(entity)
        }
    }
}

// Systems run on all RealityKit content in your app once registered.
struct MyApp: App {
    init() {
        TraceSystem.registerSystem()
    }
}