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Async / Await

Documentation version: 0.3.6

LCGUdonSharp lowers async/await at build time to frame-pool continuations — no runtime task machinery. Supported awaits: parameterless async void methods, straight-line await Task.Yield(), constant positive await Task.Delay(int), and one VRChat SDK await per behaviour.

Basic usage​

public override async void Interact()
{
    Debug.Log("[Async/Await] Interact started.");

    await Task.Yield();
    Debug.Log("[Async/Await] Continued on the next frame.");

    await Task.Delay(1000);
    Debug.Log("[Async/Await] Continued after one second.");
}

VRChat SDK awaits​

SDK awaits keep the traditional callbacks — the legacy callback body runs first, then the generated continuation runs afterward:

public override async void Interact()
{
    await VRCAsync.LoadImageAsync(_downloader, imageUrl, targetMaterial);
    // Runs after OnImageLoadSuccess/OnImageLoadError:
    Debug.Log("Texture: " + _lastDownloadedTexture);
}

public override void OnImageLoadSuccess(IVRCImageDownload result)
{
    _lastDownloadedTexture = result.Result;   // store the SDK result here
}

Supported SDK awaits​

AwaitExample
VRCAsync.LoadStringAsync(url, out result)AsyncStringDownloadExample — the out overload copies the SDK result into an instance field before the continuation.
VRCAsync.LoadImageAsync(...)AsyncImageDownloadExample — correlated by IVRCImageDownload request identity.
VRCAsync.LoadVideoAsync / WaitForVideoEndAsyncAsyncVideoLoadExample, AsyncVideoEndExample
VRCAsync.RequestGPUReadbackAsyncAsyncGpuReadbackExample
VRCAsync.RequestSerializationAsyncAsyncSerializationExample
Creator Economy listsAsyncAvailableProductsExample, AsyncPurchasesExample, AsyncProductOwnersExample

Constraints​

  • Each async method is single-flight — a second call while the continuation is pending is ignored.
  • String completion is correlated by URL — don't start another request with the same URL on the behaviour while one is pending.
  • Locals, parameters, nested awaits, explicit returns, and assigning Task<T> results directly still produce build diagnostics.

Full details in Example/AsyncAwait/README.md.

See also​