PurrDiction

Execution Flow

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This page clarifies when each override runs and how a tick proceeds from input → simulation → physics → networking → view.

At a Glance

flowchart TD
  A[Pre-Tick] --> B[Prepare Inputs]
  B --> C[Save Pre-Sim State]
  C --> D[Simulate]
  D --> E[Late Simulate]
  E --> F[Physics]
  F --> G[Save Post-Sim]
  G --> H[Networking]
  H --> I[PostSim]
  I --> J[Advance Tick]

Client reconciliation (when a verified frame arrives):

flowchart TD
  K[Verified Frame] --> L[Rollback to Tick]
  L --> M[Simulate Verified Tick]
  M --> N[Replay to Latest]
  N --> O[Update Interpolation]
  O --> P[Sync Transforms]

Per-frame view update (client):

flowchart LR
  Q[Update or LateUpdate] --> R[UpdateView per Identity]

Startup & Registration

  • PredictionManager.Awake
    • Registers instance per scene, sets Unity physics to script mode per provider, initializes pooling.
  • OnEarlySpawn
    • Registers built‑in systems (Hierarchy, Players, Physics2D/3D, Time).
    • Registers scene PredictedIdentity components and assigns IDs/owners.
  • PredictedIdentity.Setup
    • Called per identity with NetworkManager, PredictionManager, component ID, and owner.
    • On first spawn, calls LateAwake() once.

Per‑Tick (OnPreTick)

Order (server and client):

  1. Mark simulation context
  • isSimulating = true; on server, isVerified = true.
  1. Input preparation
  • Server: dequeues pending client input frames.
  • For each identity: PrepareInput(isServer, isController, localTick, extrapolate)
    • On local controller: calls your GetFinalInput, SanitizeInput, writes to history.
    • On server for remotes: consumes QueueInput or optionally extrapolates.
  1. Save pre‑simulation state
  • SaveStateInHistory(localTick) for non‑event identities.
  • Server: write initial frame payloads for state and inputs.
  1. Simulation passes
  • SimulateTick(localTick, delta) → your Simulate(...) implementation.
  • LateSimulateTick(delta) → your LateSimulate(...) implementation.
  • DoPhysicsPass() integrates Unity physics for the tick.
  1. Save post‑simulation state
  • SaveStateInHistory(localTick) for event‑handler identities.
  • Server: write event streams and send frames to clients.
  1. Post‑simulate & finish
  • PostSimulate() per identity for any finalization.
  • Finalize input/state per role (server vs client).
  • Advance localTick.
  • isSimulating = false.

Reconciliation (OnPostTick on client)

  • Receive verified server frames and compute a target tick to reconcile to.
  • Fire onStartingToRollback.
  • Perform one of:
    • In‑place: RollbackToFrame(tick) → SimulateFrameInPlace(tick) → SimulateFrame(tick, save=true)
    • From previous frame: RollbackToFrame(frame, stateTick, inputTick) → SimulateFrame(verifiedTick, save=true)
  • Mark isVerified = false, then replay to the latest local tick: ReplayToLatestTick(lastVerified + 1).
  • SyncTransforms() and UpdateInterpolation(accumulateError: true) to smooth visual corrections.
  • Fire onRollbackFinished.

View updates are not part of tick callbacks; see below.

View Update (Client)

  • PredictionManager.Update or LateUpdate (based on UpdateViewMode):
    • For each identity: UpdateView(Time.unscaledDeltaTime)
    • Identities compute/advance viewState and render visuals.
  • Ownership changes trigger OnViewOwnerChanged(old, new) inside UpdateView.

Override Cheat‑Sheet

  • Spawning/Pooling
    • OnPreSetup() — before Setup on server‑side systems.
    • LateAwake() — once on fresh spawn; view‑only setup.
    • ResetState() — clear owner/IDs and interpolation; called when reusing pooled instances.
    • Destroyed() — cleanup on despawn/unregister.
  • Input (on PredictedIdentity<INPUT, STATE>)
    • GetFinalInput(ref INPUT) — per tick, returns current frame input for the controller.
    • UpdateInput(ref INPUT) — per Unity frame; cache edge‑triggered inputs.
    • SanitizeInput(ref INPUT) — clamp/normalize before simulation.
    • ModifyExtrapolatedInput(ref INPUT) — strip non‑continuous inputs during remote extrapolation.
  • Simulation
    • SimulationStart() — before first Simulate for this identity.
    • Simulate(...) — deterministic tick logic; mutate only STATE.
    • LateSimulate(...) — optional second pass each tick.
    • PostSimulate() — finalize per tick.
  • State ↔ Unity
    • GetUnityState(ref STATE) — read Unity → state when needed.
    • SetUnityState(STATE) — apply rollback state → Unity.
  • Reconciliation / History
    • SaveStateInHistory(tick) — invoked by manager before/after simulation.
    • Rollback(tick) — restore snapshot and apply to Unity.
    • ClearFuture(tick) — drop states beyond a given tick.
    • GetLatestUnityState() — manager asks identities to resync after replays.
  • View & Interpolation
    • UpdateRollbackInterpolationState(delta, accumulateError) — accumulate/compute view corrections.
    • ResetInterpolation() — clear smoothing (e.g., teleports).
    • UpdateView(STATE viewState, STATE? verified) — render visuals.
    • OnViewOwnerChanged(old, new) — view‑only ownership transitions.