Views and Interpolation

PurrDiction separates simulation state from presentation. You simulate and reconcile state deterministically, then render a smooth view from that state. This page explains the view pipeline, interpolation, and how to customize smoothing and snapping.

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Update Flow

• Simulation runs at the network tick rate, including local prediction and server‑verified replays.

• Each frame, the Prediction Manager calls UpdateView(deltaTime) on predicted identities in either Update or LateUpdate based on the Update View Mode setting.

• For PredictedIdentity<STATE>:

  • A small interpolation buffer smooths from the last verified state toward the latest predicted state.

  • UpdateView(STATE viewState, STATE? verified) receives the interpolated view plus the most recent verified snapshot, if available.

Key APIs on PredictedIdentity<STATE>:

• public override void ResetInterpolation()

• public override void UpdateRollbackInterpolationState(float delta, bool accumulateError)

• protected virtual void ModifyRollbackViewState(ref STATE state, float delta, bool accumulateError)

• protected virtual void UpdateView(STATE viewState, STATE? verified)

Terminology:

• viewState: The state you should render this frame (often interpolated and error‑corrected).

• verified: The last server‑verified state if present, otherwise null.

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Interpolation Buffer

• A per‑identity interpolation helper buffers several ticks (~tickRate/10, min 2) to absorb jitter.

• Default interpolation blends linearly: IMath<T>.Add/Scale/Negate on STATE. You can override Interpolate(STATE from, STATE to, float t).

• When reconciliation happens, the system snapshots and adjusts the buffer to smoothly approach the corrected timeline.

Tip: If your STATE contains non‑linear fields (e.g., quaternions), override Interpolate and use slerp or domain‑specific blending.

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PredictedTransform

PredictedTransform demonstrates a robust, out‑of‑the‑box interpolation and correction strategy:

• Uses TransformInterpolationSettings to control smoothing and snap thresholds for both position and rotation.

• Accumulates error on reconcile and gradually corrects it over multiple frames.

• Snaps (teleports) when error exceeds an upper threshold; skips correction when below a lower threshold.

Adjustable settings via TransformInterpolationSettings:

• useInterpolation: Toggle smoothing corrections.

• positionInterpolation and rotationInterpolation (PredictedInterpolation):

  • correctionRateMinMax: Base correction speed range.

  • correctionBlendMinMax: Scales correction rate based on error magnitude.

  • teleportThresholdMinMax: Lower bound to ignore tiny error; upper bound to snap immediately.

When you need to reset visual drift (e.g., teleporting gameplay), call ResetInterpolation() to clear accumulated error and re‑align view with prediction.

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Owner vs. Controller

• isOwner: True when the identity’s owner matches PredictionManager.localPlayer.

• isController: True for the owner on clients; on server, also true for bots/AI.

• Views should be purely visual; avoid branching simulation on these flags. Use them to toggle camera, UI, or local effects.

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Tuning and Debugging

• Choose Update vs LateUpdate from the Prediction Manager (Update View Mode) if visuals depend on post‑physics order.

• Log and compare viewState against verified to validate correction behavior.

• If you see oscillation, widen lower thresholds or increase correction rate.

• For large warps (portals, respawns), prefer snapping by calling ResetInterpolation().