Subsystems

InteractionSubsystem

UDRW_InteractionSubsystem (UWorldSubsystem)

Purpose: Manages ocean water interaction effects (ripples, wakes, foam): tracks active sources and renders them into a scrolling buffer that follows the camera. Buffer resolution is configurable via RTResolution.

Access: GetWorld()->GetSubsystem<UDRW_InteractionSubsystem>()

Properties

Property	Type	Default	Description
RTResolution	int32	2048	Render target resolution. Range: 512–4096.
WorldCoverage	float	51200.0	World-space coverage (cm). Range: 1000–200000.
DecayRate	float	0.2	Effect fade rate. Range: 0.01–5.
AdvectionStrength	float	0.5	Wake propagation. Range: 0–1.
DiffusionStrength	float	0.5	Wake spread. Range: 0–1.
MaxSourcesPerFrame	int32	100	Performance cap. Range: 1–500.
FixedUpdateRateHz	float	30.0	Update rate. Range: 10–60.
bEnabled	bool	true	Master enable.
DefaultInteractionDataAsset	InteractionDataAsset	:	When assigned, overrides the per-property defaults below with the asset’s values.
Performance
MinScreenSizeThreshold	float	0.002	Sources whose Radius / Distance falls below this are culled. Higher = more aggressive culling. Range: 0–0.1.
MaxInteractionDistance	float	100000.0	Sources beyond this distance (cm) are culled regardless of size. Set to 0 to disable.
Thresholds
MinSpeedForRipple	float	15.0	Minimum horizontal speed (cm/s) to generate ripples. Range: 1–100.
MinSpeedForWake	float	200.0	Minimum horizontal speed (cm/s) for wake generation. Range: 50–500.
MinRadiusForWake	float	100.0	Minimum object radius (cm) to generate wakes. Range: 10–500.
MinVerticalSpeedForSplash	float	30.0	Minimum vertical speed (cm/s) to register an impact splash. Range: 10–200.
ImpactSplashDuration	float	3.0	Seconds an impact splash remains active. Range: 0.5–10.

Blueprint API

Function	Returns	Description
RegisterInteractionSource(PhysicsBody)	void	Register a physics body.
UnregisterInteractionSource(PhysicsBody)	void	Unregister.
SpawnSplashAtLocation(Position, Radius, Intensity)	void	Manual splash spawn.
SetEnabled(bEnabled)	void	Toggle system.
SetGridManager(GridManager)	void	Wire up the grid manager (called automatically by BP_DynamicRealWater).
ClearInteractions()	void	Clear all effects.
GetInteractionRT()	RenderTarget2D	Current interaction RT.
GetRTWorldCenter()	FVector2D	World-space centre of the scrolling buffer.
GetWorldCoverage()	float	World-space extent (cm).
IsInteractionEnabled()	bool	True when the subsystem is enabled and the RT is initialised.
GetRegisteredSourceCount() / GetActiveSourceCount()	int32	Source metrics.

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DebugSubsystem

UDRW_DebugSubsystem (UWorldSubsystem)

Purpose: Centralized debug visualization for all DRW physics systems. Handles force arrows, velocity vectors, on-screen stats, and shape visualization.

Access:

UDRW_DebugSubsystem* Debug = GetWorld()->GetSubsystem<UDRW_DebugSubsystem>();
Debug->AddForce(TEXT("Buoyancy"), Force, Location, EDRW_DebugCategory::Buoyancy, this);

Console variables

Runtime toggles for the visualization. Set from the in-editor console (~) or from any Exec node.

Property	Type	Description
DRW.Debug	bool	Master toggle for all debug visualization.
DRW.Debug.cat	int32 (bitmask)	Categories to display (bitmask).
DRW.Debug.filter	bool	Filter debug to specific actor.
DRW.Debug.help	bool	Show all debug commands.
DRW.Debug.net	bool	Show net force arrow.
DRW.Debug.preset	bool	Apply debug preset.
DRW.Debug.scale	float	Arrow length scale.
DRW.Debug.shapes	float	Draw a debug shape (box, sphere, capsule) with optional label.
DRW.Debug.stats	float	Show on screen text stats.
DRW.Debug.status	bool	Show current debug settings.
DRW.Debug.thickness	float	Arrow thickness.
DRW.Debug.threshold	float	Minimum force (N) to display.

Subsystem properties

The same settings exposed as C++ properties on the subsystem: set programmatically when you don’t want to type a console command.

Property	Type	Default	Description
bEnabled	bool	false	Master toggle.
EnabledCategories	int32 (bitmask)	All	Buoyancy, Gravity, Damping, Drag, Thrust, Steering, Stability, Velocity.
bShowPerShape	bool	true	Per-shape vs aggregate forces.
bShowOnScreenStats	bool	true	On-screen text overlay.
bShowNetForce	bool	true	Show the per-actor net-force vector.
Display
ArrowScale	float	0.05	Force arrow length scale. Range: 0.0001–1.
ArrowThickness	float	5.0	Force arrow line thickness. Range: 0.5–10.
MinForceThreshold	float	0.1	Min force to display (N).
TextScale	float	1.25	On-screen text scale. Range: 0.5–3.
DrawDuration	float	0.0	Persistence per draw call (seconds). 0 = single frame.
bOffsetOverlappingVectors	bool	true	Spread arrows that overlap in world space so they’re individually readable.
OverlapOffsetSpacingCm	float	50.0	Spacing between offset arrows (cm).
OverlapLocationQuantizeCm	float	5.0	Position-quantisation tolerance for grouping overlapping arrows.

Usage: DRW components push debug data into this subsystem automatically while their physics tick runs. Users interact with the subsystem through its properties: toggling categories at runtime, changing arrow scale, filtering to specific actors. The push API is C++-only.