# PurrNet - Overview

A concrete `NetworkTransportBridge` implementation that wires the Game Creator 2 Networking Layer on top of **PurrNet**.

{% embed url="<https://www.youtube.com/watch?v=5LlXQH1y_1Y>" %}

### Layout

* `PurrNetTransportBridge.cs` - `NetworkTransportBridge` implementation.
* `PurrNetNetworkMessages.cs` - `GC2InputBroadcast` / `GC2StateBroadcast` packets (both `IPackedAuto`, auto-serialized by PurrNet).
* `PurrNetDemoCanvasUI.cs` - generated UGUI host/join/disconnect overlay used by the PurrNet wizard and demo scenes. Reflectively reads/writes `address` / `serverPort` on the active transport (UDP, WebTransport, ...), so no transport plumbing is needed.
* `PurrNetHostJoinUI.cs` - older lightweight IMGUI host/join overlay for manual scenes that do not want generated UGUI.
* `Arawn.GameCreator2.Networking.Transport.PurrNet.asmdef` - isolated asmdef so the core GC2 networking assembly stays transport-agnostic.
* Editor companion: `Assets/Arawn/NetworkingLayerForGC2/Editor/Transport/PurrNet/` contains `PurrNetSceneSetupWizard` (menu: `Game Creator > Networking Layer > PurrNet Scene Setup Wizard`) and an isolated editor asmdef.

### Scene setup (automated)

<figure><img src="/files/YJ1FWtBWFh1wghhLILIL" alt=""><figcaption></figcaption></figure>

Open `Game Creator > Networking Layer > PurrNet Scene Setup Wizard`. It will:

* Create or reuse a PurrNet `NetworkManager`.
* Add the selected transport (UDP / WebTransport / Local / keep existing) and write the default address/port into supported transports.
* Create or reuse the core GC2 networking managers: `NetworkSecurityManager`, `NetworkCoreManager`, `NetworkAnimationManager`, `NetworkMotionManager`, and `NetworkVariableManager`.
* Create or reuse the core PurrNet bridges: `PurrNetTransportBridge`, `PurrNetVariableTransportBridge`, and `PurrNetAnimationMotionTransportBridge`.
* Create or reuse selected module managers and PurrNet module bridges for Stats, Inventory, Melee, Shooter, Quests, Dialogue, Traversal, and Abilities.
* When Shooter is selected, require the GC2 Shooter Sight hook patch before setup continues. This patch can also be applied manually from `Game Creator > Networking Layer > Patches > Shooter Sight > Patch (Remote Camera Safety)`.
* Optionally create a `NetworkSessionProfile`, `NetworkPrefabs` asset, `PurrNetDemoPlayerSpawner`, demo runtime UI, and demo controls UI.
* Optionally prepare an assigned Player Prefab with `NetworkIdentity`, `NetworkCharacter`, `PurrNetNetworkCharacterAuto`, selected module controllers, local variable sync, and pre-registered Network Dash/Gesture animation clips.
* Parent generated scene helpers under a single session root for scene hygiene.

The wizard has six pages:

<figure><img src="/files/AQNdys6DQRRK5nsqw5Ed" alt=""><figcaption></figcaption></figure>

1. **Project** - choose a project template and expected player count. Non-Custom templates immediately apply recommended modules, tick-rate, session preset, and helper defaults. Custom keeps current manual settings unchanged.
2. **Modules** - choose which GC2 modules should replicate over PurrNet. Core, Variables, Animation, and Motion are always included.
3. **Transport** - choose UDP, WebTransport, Local, or existing/manual transport setup.
4. **Core** - review generated managers, bridges, NetworkManager settings, session profile generation, and Custom session fields.
5. **Scene** - assign and optionally prepare the Player Prefab, create NetworkPrefabs, register network instruction animation clips, and choose helper UI.
6. **Review** - inspect the final setup before applying it.

### Scene setup (manual)

1. Add a `NetworkManager` (PurrNet) to the scene with its transport of choice (UDP, Steam, UTP, WebTransport, etc.).<br>

   <div data-with-frame="true"><figure><img src="/files/THCuXnCO2USBLbldo0QE" alt=""><figcaption></figcaption></figure></div>
2. Add `PurrNetTransportBridge`, `PurrNetVariableTransportBridge`, and `PurrNetAnimationMotionTransportBridge` to the scene.<br>

   <div data-with-frame="true"><figure><img src="/files/YMQUnUGapFRuoiMv35Dz" alt=""><figcaption></figcaption></figure></div>

   <div data-with-frame="true"><figure><img src="/files/ulo0Gfl6X07hDbHHewg9" alt=""><figcaption></figcaption></figure></div>

   <div data-with-frame="true"><figure><img src="/files/MvjDPgUmwqsrTdvmH5Fj" alt=""><figcaption></figcaption></figure></div>
3. Add the shared managers used by your project, at minimum `NetworkSecurityManager`, `NetworkCoreManager`, `NetworkAnimationManager`, `NetworkMotionManager`, and `NetworkVariableManager`.<br>

   <div data-with-frame="true"><figure><img src="/files/KR936I0YYKmaCbWjkWEn" alt=""><figcaption></figcaption></figure></div>

   <div data-with-frame="true"><figure><img src="/files/BgZwSk1BLLizJ2kovtwl" alt=""><figcaption></figcaption></figure></div>

   <div data-with-frame="true"><figure><img src="/files/VxEZCs9yHEsH0mfY2JgH" alt=""><figcaption></figcaption></figure></div>

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   <div data-with-frame="true"><figure><img src="/files/VLQpzB2fPImFUKuuTqAG" alt=""><figcaption></figcaption></figure></div>
4. Add each selected module manager and matching PurrNet module bridge (`PurrNetMeleeTransportBridge`, `PurrNetShooterTransportBridge`, etc.).
5. Initialize the GC2 managers when PurrNet starts. The bridge components do this automatically when configured like the wizard output; custom manual setups should follow [`PurrnNet Quickstart`](/networking-layer-for-gc2/purrnet-overview.md).
6. Prepare spawned player prefabs with `NetworkIdentity`, `NetworkCharacter`, `PurrNetNetworkCharacterAuto`, and selected per-player module controllers. Add `NetworkVariableController` only when the prefab uses local GC2 variables that must synchronize.<br>

   <div data-with-frame="true"><figure><img src="/files/EljGwZevAswBrnsSsjss" alt=""><figcaption></figcaption></figure></div>

   <div data-with-frame="true"><figure><img src="/files/WUR9IVppm3SaUxd6DU64" alt=""><figcaption></figcaption></figure></div>

   <div data-with-frame="true"><figure><img src="/files/Gczfvx2wOB8P6porc7BZ" alt=""><figcaption></figcaption></figure></div>

### Host / Join overlay

<figure><img src="/files/fTGjSiRMxoT8lAQ23xUu" alt=""><figcaption></figcaption></figure>

The wizard-created `PurrNetDemoCanvasUI` builds a UGUI panel at runtime with Host, Join by IP, Disconnect, role, and connection-state controls. This is the default quick-start UI for direct-connect tests: Player A clicks Host, Player B enters Player A's LAN/public IP and port, then clicks Join.

The optional `PurrNetHostJoinUI` component remains available for manual scenes that prefer a tiny IMGUI overlay with no generated Canvas. Replace either helper with your own menu UI for production builds; both are validation/front-end starters, not a finished game menu.

### Packet flow

* Client input: `SendToServer(characterId, inputs[])` → `GC2InputBroadcast` over `UnreliableSequenced` (configurable) → server subscribes and raises `OnInputReceivedServer(senderClientId, characterId, inputs)`.
* Server state: `SendToOwner(...)` / `Broadcast(...)` → `GC2StateBroadcast` over `UnreliableSequenced` → clients raise `OnStateReceivedClient(...)`.

Host-local input is short-circuited: when running as host, the bridge dispatches input through the server pipeline directly instead of round-tripping the transport.

### Motion smoothing and localhost tests

Most first tests run as two local game instances connected to `127.0.0.1`. That setup has very low latency, but remote characters can still look uneven if the state stream is sampled too sparsely or if snapshots are filtered twice. The PurrNet demo scene uses the `Duel` session preset and a 60 Hz PurrNet tick rate so local testing has a high-quality baseline.

For `NetworkCharacter` players, let the GC2 networking driver own motion presentation. Do not add a PurrNet `NetworkTransform` to the same player root, because both systems will try to write position/rotation. Use the `NetworkSessionProfile` to tune `serverStateBroadcastRate`, `stateApplyRate`, and `interpolationDelay` for your target game.

Owner-side reconciliation corrects the authoritative root immediately and smooths the visible GC2 model through `UnitDriverNetworkClient`. If a custom camera follows the character root directly and still shows correction bumps, offset the camera target using `ReconciliationVisualOffset` while `IsReconciling` is true, or follow the model/mannequin instead of the root.

Lag compensation is separate from visual smoothing. The `LagCompensationManager` records historical server-side positions so hitscan, projectile, melee, and ability hit validation can rewind targets to the time a client acted. It does not make remote transforms render more smoothly.

### Ownership

* Automatic: if the spawned `NetworkCharacter` (or any parent) has a PurrNet `NetworkIdentity`, ownership is read from `identity.owner` and mapped via `SetCharacterOwner(networkId, ownerClientId)`.
* Manual: call `SetCharacterOwner(networkId, ownerClientId)` yourself if you spawn characters outside PurrNet's ownership system. `PlayerID.id` values fit in `uint` in practice, so they can be used directly as `ownerClientId`.

### Channels

Defaults are `UnreliableSequenced` for both input and state streams. Flip them to `ReliableOrdered` from the inspector if your project needs guaranteed delivery at the cost of latency.

### Module wiring

The PurrNet integration includes bridge components for the core layer and each supported optional module. When a module is selected in the PurrNet Scene Setup Wizard, the wizard creates/reuses both the GC2 module manager and the PurrNet bridge for that module.

Custom transports or hand-written PurrNet setups should still follow the public transport contract in `Documentation/TRANSPORT_QUICKSTART.md`: wire outbound manager/controller delegates to transport sends and route inbound packets to the matching `Receive*` APIs.


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