How to respond to changes in immersion level
When using progressive immersion, our apps can respond to changes when the user turns the Digital Crown.
In this example, we create a particle emitter that uses the snow preset. Then we listen for changes to immersion level with the onImmersionChange modifier. We can use the amount provided by this modifier to as a multiplier for the speed and birth rate of the particle emitter.
struct ImmersiveView: View {
@Environment(AppModel.self) private var appModel
@State var immersionAmount: Float = 0
var speed: Float = 1
var birthRate: Float = 3000
var body: some View {
RealityView { content in
// Create some snow!
var snowParticles = ParticleEmitterComponent.Presets.snow
snowParticles.speed = 0.5
snowParticles.mainEmitter.birthRate = 2000
snowParticles.emitterShape = .sphere
snowParticles.emitterShapeSize = [5,5,5]
snowParticles.mainEmitter.size = 0.01
let snowEntity = Entity()
snowEntity.name = "Snow"
snowEntity.components.set(snowParticles)
content.add(snowEntity)
} update: { content in
if let snow = content.entities.first(where: { $0.name == "Snow" }){
// Get the particle component
if var snowParticles = snow.components[ParticleEmitterComponent.self] {
// Adjust the speed and birthrate using the immersion amount
snowParticles.speed = speed * immersionAmount
snowParticles.mainEmitter.birthRate = birthRate * immersionAmount
// Reassign the component to the entity
snow.components.set(snowParticles)
}
}
}
.onImmersionChange { inintial, new in
immersionAmount = Float(new.amount ?? 0)
}
}
}Whenever the immersion level changes (the user turns the Digital Crown) onImmersionChange will update the state var immersionAmount. The RealityView update closure will respond to this change and will modify the particle component.
Note: I added a floor mesh here because without it I felt like I was falling through the universe…
Video demo
Video demo showing a fully immersed progressive space with dense snow particles. The user dials the immersion down and the particle system emits less snow.
Sample code is available in Garden17 in the Step Into Example Projects repo.
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