Explore advances in RealityKit

// Enable soft shadows for the hearth spotlight
    
guard var shadow = hearthSpotlight.components[SpotLightComponent.Shadow.self] else {
    // handle error
}
shadow.lightSize = 0.7 // meters
    
shadow.quality = .medium // or .high
// shadow.quality = .low // will result in hard shadows
    
hearthSpotlight.components.set(shadow)

// Create one of the planetarium spotlights
    
let spotLightEntity = Entity()
spotLightEntity.components.set(SpotLightComponent(
    color: .white,
    intensity: intensity,
    innerAngleInDegrees: innerAngle,
    outerAngleInDegrees: outerAngle,
    attenuationRadius: attenuationRadius,
))
    
let projectiveTexture: TextureResource = generateStarsAndNebulaeTexture()
spotLightEntity.components.set(SpotLightComponent.ProjectiveTexture(
    texture: projectiveTexture
))

// Enable physical space lighting
    
spotLightEntity.components.set(SpotLightComponent.SurroundingsLight())

// Querying the navigation mesh in Chaparral Village

extension Entity {
    public func navigate(/* ... */) async {
        let navigator = try! NavigationController(entity: self)
        guard let result = await navigator.computePath(from: fromPosition, to: toPosition) 
        else {
            return
        }
        if result.isEmpty {
            return
        }
        for node in result {
            switch node.category {
                case .meshPoint:
                    finalPath.append(node.position)
                case .offMeshConnection:
                    // handle ladders
            }
        }
    }
}

// Pin the curtains to the Alchemist's lab

for (pin, pinComponent) in pins {
        let position = pin.position(relativeTo: event.entity)
        let selectionSphere = ClothSphereShape(radius: pinComponent.radius)
    
        let vertices = clothMesh.vertices(in: .sphere(selectionSphere),
                                    center: position)
        clothBody.motionTypes.set(vertexIndices: vertices, value: .kinematic)
}

// Create entity with LODs
    
let lod0 = [ModelEntity(mesh: lodMesh0)]
let lod1 = [ModelEntity(mesh: lodMesh1)]
let lod2 = [ModelEntity(mesh: lodMesh2)]

let entity = Entity()

LevelOfDetailComponent.addByCameraDistance(to: entity, levels: [
    (entities: lod0, maxDistance: 1.0 /* meters */), // highest detail
    (entities: lod1, maxDistance: 5.0),              // medium detail
    (entities: lod2, maxDistance: .infinity),        // lowest detail
])

// Create entity with LODs
    
let lod0 = [ModelEntity(mesh: lodMesh0)]
let lod1 = [ModelEntity(mesh: lodMesh1)]
let lod2 = [ModelEntity(mesh: lodMesh2)]

let entity = Entity()

LevelOfDetailComponent.addByScreenArea(to: entity, levels: [
    (entities: lod0, minArea: 0.2 /* fraction of screen area */),  // highest detail
    (entities: lod1, minArea: 0.1),                                // medium detail
    (entities: lod2, minArea: 0.01),                               // lowest detail
])

// Respond to changes in device thermal state
    
NotificationCenter.default.addObserver(of: ProcessInfo.self,
                                       for: .thermalStateDidChange) {_ in
    switch ProcessInfo.processInfo.thermalState {
        case .nominal, .fair:
            // Stay the course
        case .serious, .critical:
            // Improve performance by:
            // More aggressive LOD switching
            // Lower shadow quality
    }
}

// Create Gaussian splat resource and component

let resource = try GaussianSplatResource.BufferResource(count: splatCount,
                                                        position: positionBuffer,
                                                        scale: scaleBuffer,
                                                        rotation: rotationBuffer,
                                                        opacity: opacityBuffer,
                                                        sphericalHarmonics:
                                                                                                                    (sphericalHarmonicsBuffer, degree))

let splatResource = GaussianSplatResource(resource)

let splatComponent = GaussianSplatComponent(splatResource)

splatEntity.components.set(splatComponent)

// Create and use custom reverb mesh

let mesh: ReverbMeshResource = .shoebox(size: [5, 4, 6])
    
let reverb: Reverb = .simulated(mesh: mesh, materials: [.dryWall])
    
entity.components.set(ReverbComponent(reverb: reverb))

// Create custom materials for custom reverb mesh
    
let thickCarpet: Audio.Material = .carpet.scalingAbsorption {freq in 0.1 }
    
let bookshelf: Audio.Material
    
// Absorption coefficients by center frequency:
// 31.5Hz, 63Hz, 125Hz, 250Hz, 500Hz, 1kHz, 2kHz, 4kHz, 8kHz, 16kHz
let bookshelfAbsorption = Audio.Absorption(
    [0.10, 0.15, 0.28, 0.20, 0.15, 0.10, 0.10, 0.07, 0.07, 0.05])
    
// Scattering coefficients for: 500Hz, 1000Hz, 4000Hz
let bookshelfScattering = Audio.Scattering([500: 0.5, 1000: 0.6, 4000: 0.7])
    
bookshelf = .init(absorption: bookshelfAbsorption,
              scattering: bookshelfScattering)