State Handling

STATE is the single source of truth for your simulation. PurrDiction records, reconciles, and interpolates states so clients stay responsive while remaining consistent with server authority.

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Requirements

• STATE must be a struct implementing IPredictedData<STATE> (which extends IMath<STATE> and IPackedAuto).
• Provide deterministic math on your state via IMath<T> methods (the default linear interpolation uses Add, Scale, Negate).

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What Goes in STATE

• Simulation‑critical data only: positions, rotations, velocities, timers, flags; anything that affects future ticks.
• Do not store transient view data; compute those in UpdateView.

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Lifecycle and Reconciliation

• Simulation loop writes currentState each tick.
• PurrDiction saves snapshots and reconciles against server frames as they arrive.
• On rollback:
  • ReadState loads the verified snapshot.
  • Rollback(tick) applies it and calls SetUnityState(state) for external components.
  • UpdateRollbackInterpolationState(delta, accumulateError) adjusts view smoothing.

Unity bridging:

• protected override void GetUnityState(ref STATE state) — Read Unity → STATE when needed.
• protected override void SetUnityState(STATE state) — Write STATE → Unity on rollback.

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View vs Verified

• viewState is the smoothed state to render this frame.
• verifiedState exposes the most recent authoritative snapshot, when present.
• Override UpdateView(STATE viewState, STATE? verified) to drive visuals.
• Call ResetInterpolation() to clear accumulated error (e.g., teleports).

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Example: Minimal STATE

public struct MyState : IPredictedData<MyState>
{
    public Vector3 pos; public Quaternion rot;
    public void Dispose() {}
    // IMath<MyState> default ops come from packer codegen; override Interpolate if non-linear
}

public class Mover : PredictedIdentity<MyState>
{
    protected override MyState GetInitialState() => new MyState { pos = transform.position, rot = transform.rotation };
    protected override void GetUnityState(ref MyState s) { s.pos = transform.position; s.rot = transform.rotation; }
    protected override void SetUnityState(MyState s) { transform.SetPositionAndRotation(s.pos, s.rot); }
    protected override void Simulate(ref MyState s, float dt) { /* mutate s deterministically */ }
    protected override void UpdateView(MyState view, MyState? verified) { transform.SetPositionAndRotation(view.pos, view.rot); }
}