#include <ComposableCameraComputeNodeBase.h>

Inherits: UComposableCameraCameraNodeBase Subclassed by: UComposableCameraComputeDistanceToActorNode

Base class for one-shot compute nodes that run on the BeginPlay chain.

Compute nodes are NOT camera nodes in the per-frame-evaluated sense. They run exactly once, between per-node Initialize and the first TickCamera, and their job is to perform arbitrary math / data shaping in C++ and publish the result to camera-level internal variables (or to output pins that are then plumbed through the graph).

Why a dedicated base class instead of "just use a camera node"? ──────────────────────────────────────────────────────────────

• Camera nodes are walked per-frame by TickCamera and multicast through OnPreTick / OnPostTick. A compute node must not touch any of that — it would otherwise burn hot-path time on values that never change.

• Compute nodes still need the pin system (GetInputPinValue / SetOutputPinValue / Set/GetInternalVariable), which only lives on UComposableCameraCameraNodeBase. Inheriting from it is the cheapest way to get that plumbing without duplicating the RuntimeDataBlock wiring.

• The editor-side graph hosts these on a separate BeginPlay chain rooted at UComposableCameraBeginPlayStartGraphNode, parallel to how regular camera nodes wire off the main Start sentinel. The sync/rebuild phases classify a UComposableCameraNodeGraphNode as camera-chain vs compute-chain by testing IsA on its underlying NodeTemplate, which is exactly this base class — so the runtime discriminator "this belongs on the BeginPlay chain" is the same type check the editor uses.

Why a dedicated class instead of UObject? ─────────────────────────────────────────

• K2 math graph nodes from the BlueprintGraph module do not work in our custom UEdGraph without significant engineering. The pragmatic Option B is: author a compute node in C++, use FMath / FVector / FQuat / UKismetMathLibrary directly, publish the result to internal variables, and let downstream camera nodes consume them.

• Subclasses describe their inputs and outputs with the same pin declaration system as camera nodes (GetPinDeclarations), which keeps editor palette / pin rendering / type-asset authoring uniform.

Lifecycle ─────────

1. Camera activation fires AComposableCameraCameraBase::InitializeNodes.

2. Each compute node has OnInitialize_Implementation invoked via the inherited Initialize() path (same machinery camera nodes use). This is where one-time setup, ref caching, and exposed-parameter reads belong.

3. AActor::BeginPlay fires, which calls AComposableCameraCameraBase::BeginPlayCamera(), which walks the ComputeNodes array in order and calls ExecuteBeginPlay() on each.

4. First TickCamera then runs with whatever internal variables / output pins the compute chain published.

Compute nodes must NOT register for OnPreTick / OnPostTick and must NOT override OnTickNode_Implementation — they are not per-frame nodes. The camera's InitializeNodes loop intentionally skips tick-delegate wiring for compute nodes for exactly this reason.

Public Methods¶

ExecuteBeginPlay¶

virtual inline

virtual inline void ExecuteBeginPlay()

Execute this compute node's one-shot work.

Called from AComposableCameraCameraBase::BeginPlayCamera, after every node on the camera (both camera nodes and compute nodes) has already had Initialize() / OnInitialize_Implementation() run. By the time this fires, OwningCamera / OwningPlayerCameraManager / RuntimeDataBlock are all wired, so GetInputPinValue / SetOutputPinValue / Get/SetInternalVariable are all safe to use.

The outgoing camera pose (the pose the previous camera was evaluating before this one became active) is available via OwningPlayerCameraManager->GetCurrentCameraPose() — this is the same value AActor::BeginPlay used to pass into BeginPlayCamera as a parameter before Step 4a removed that argument.

Plain virtual (not a BlueprintNativeEvent) for 4a. If Blueprint authoring of compute nodes becomes a requirement later, promote this to a BlueprintNativeEvent following the same OnFoo / OnFoo_Implementation pattern used by OnInitialize and OnTickNode on the parent class.