Donovan’s Vision Blog

Playing sounds

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With a Jenga game capable of detecting collisions, we can experiment with adding sounds to collision events.

Prepare an audio file #

To prepare a sound for this test, I grabbed a free file from Pixabay and used Audacity to export it as WAV, then an online converter to create a caf file. This can be added to the project and accessed when needed.

Download the audio file here.

AudioFileResource extension #

In order to load the file, we need to set up an extension to AudioFileResource. This will allow us to load the necessary audio files in our views. Add this as a standalone file such as AudioFileResource-loadBundleFile.

extension AudioFileResource {
    static func loadBundleFile(_ filename: String) -> AudioFileResource {
        if let audio = try? AudioFileResource.load(named: filename) {
            audio
        } else {
            fatalError("Unable to local audio file resource: \(filename) from bundle.")
        }
    }
}

Set up Spatial Audio on entity #

When setting up the piece entity in the view model, we can set the entity to use Spatial audio:

piece.spatialAudio = SpatialAudioComponent()

The SpatialAudioComponent method can be configured with directivity (the radiated pattern of sound), gain (the overall volume) and more.

We can also set orientation on the sound to work in combination with directivity using piece.orienation:

audioSource.orientation = .init(angle: .pi, axis: [0, 1, 0])

These can be set directly also such as when a collision event occurs and we might want to specify a value calculated in some way.

entity.spatialAudio?.directivity = .beam(focus: 0.75)

Loading sound #

In the ImmersiveView, add a line above the body that uses this loadBundleFile method to load the sound:

let collisionAudio = AudioFileResource.loadBundleFile("tap01.caf")

Play audio from an entity #

We can have the entity play this sound. As the Vision Pro makes use of spatial audio, the sound will sound like it's coming from the entity that plays it.

We can have the entity involved in a collision play the sound when a collision event occurs:

subscription = content.subscribe(to: CollisionEvents.Began.self, on: floor) { collisionEvent in
    collisionEvent.entityB.playAudio(collisionAudio)
}

The important detail here is that we can have entity.playAudio(audioFile) play the sound where needed.