Panda3D.Async

Zero-allocation async/await for the Panda3D C# bindings.

Heavily inspired by UniTask.

Provides:

• PandaTask / PandaTask<T> — a struct task type analogous to UniTask, with a pooled state-machine runner (no allocation for sync-completed awaits or per-frame yields).
• PandaTaskCompletionSource — safe to complete from any thread; backed by a native AsyncFuture so cross-thread signalling is handled by the existing atomic state machine.
• Chain-aware continuations — after await, control resumes on the same AsyncTaskChain it started on. ConfigureAwait(false) opts out.
• SynchronizationContext bridge — await httpClient.GetAsync(…) inside a coroutine automatically resumes on the originating chain, so scene-graph mutation after a network call is thread-safe.
• Interop with System.Threading.Tasks.Task via AsTask() / PandaTask.FromTask().

Depends on

• Panda3D.Interop 1.11.*

Nothing else. All native support (the ManagedAsyncTask class and the AsyncFuture C# extension methods) ships inside the existing Panda3D.Runtime.{rid} packages — Panda3D.Async is pure managed code.

Samples

• samples/asteroids-async — Asteroids ported to coroutines. Side-by-side with the imperative raw-asteroids sample, this is the minimal "look, the same game, but with await NextFrame() and await Delay()" comparison.

• samples/mission-control — interactive solar-system tech demo. Textured planets orbit a sun on per-planet coroutines while a HUD reflects what the engine is doing. Keys exercise the async features the asteroids sample doesn't:

  Key	Demonstrates
  F	Periodic + on-demand HTTP fetch — await httpClient.GetStringAsync(...) resumes on the scene chain via the SynchronizationContext bridge.
  P	One-shot HTTP ping with measured roundtrip.
  R	CPU offload — await PandaTask.SwitchToChain("workers") runs heavy compute on worker threads, hops back to "default" before mutating planet state.
  G	Native async asset load — loader.MakeAsyncRequest + await IAsyncFuture to splice a freshly-loaded model into the running scene.
  S / L	Save/load orbit state via File.WriteAllTextAsync / ReadAllTextAsync — Task awaited inside a PandaTask coroutine.
  C	Cooperative cancellation — replaces the in-flight CancellationTokenSource.
  ESC	Quit.

  Always-on background coroutines: per-planet orbit + axial spin, slowly-orbiting camera, periodic HTTP heartbeat, and a real Thread-backed sensor producer feeding a Channel — its startup is gated on a cross-thread PandaTaskCompletionSource the consumer awaits.

  Set MC_AUTOQUIT=N to auto-quit after N seconds (handy for smoke tests).