Components

BuoyancyComponent

UDRW_BuoyancyComponent

Purpose: Simulates physically accurate buoyancy with per-shape force calculation. Buoyant force is integrated against water heights sampled non-blocking from the GPU, so gameplay reads never stall the main thread.

Attach To: Any actor with a physics-simulating mesh (static mesh, skeletal mesh).

Required Components: PhysicsBodyComponent (defines shapes).

Properties

Property	Type	Default	Description
Setup
WaterHeightmapRenderTarget	RenderTarget2D	:	Heightmap RT (auto-assigned by GridManager).
WaterDepthmapRenderTarget	RenderTarget2D	:	Depth map RT (auto-assigned by GridManager).
bEnableMultiplayerSupport	bool	true	Enable replication.
bPlayableCharacter	bool	false	Character mode (different force application).
Water properties
WaterDensity	float	1025.0	Water density kg/m³. Range: 900–1100.
WaterViscosity	float	0.01	Viscosity Pa·s. Range: 0.001–0.1.
InWaterThreshold	float	0.01	Min submersion ratio for bIsInWater. Range: 0.001–0.5.
Simulation
UpdateMode	EDRWBuoyancyUpdateMode	FixedOnly	EventTick, FixedSubstep (WIP), or FixedOnly (recommended).
CalculationRateHz	float	30.0	Fixed timestep rate. Range: 1–120.
InterpolationStrength	float	0.15	Smoothing between snapshots. Range: 0–1.
PhysicsQuality	EDRWPhysicsQuality	Async	Async, Mixed, or Runtime: see Physics quality modes.
InteractionHeightMultiplier	float	1.0	Contribution of interaction effects (wakes, ripples) to buoyancy sampling. Set to 0 to make ripples visual-only.
Velocity limits
MaxLinearSpeed	float	50.0	Max speed before damping (m/s). Range: 1–100.
MaxAngularSpeed	float	10.0	Max angular speed (rad/s). Range: 0.5–20.
VelocityDampingStrength	float	0.1	Damping aggressiveness. Range: 0.01–1.
Rotational damping
PitchRollDampingMultiplier	float	1.0	Multiplier on pitch/roll damping.
YawDampingMultiplier	float	1.0	Multiplier on yaw damping.
Heave damping
bEnableHeaveDamping	bool	true	Vertical oscillation damping.
HeaveDampingCoefficient	float	0.7	Fraction of critical damping. Range: 0.1–2.
HeaveAddedMassCoefficient	float	1.0	Vertical added mass. Range: 0.3–2.
HeaveVelocityThreshold	float	5.0	Below this vertical speed (cm/s), heave damping tapers off. Range: 0.5–30.
Lateral added mass
bEnableLateralAddedMass	bool	true	Apply added-mass effects to surge and sway motion (resists drifting and longitudinal acceleration).
SurgeAddedMassCoefficient	float	0.1	Forward / backward added-mass fraction. Typically small (streamlined hulls 0.05–0.15, blunt objects up to 0.5).
SwayAddedMassCoefficient	float	0.8	Sideways added-mass fraction. Typically large for ship hulls: this is the main “doesn’t slide sideways” knob.
Slamming
bEnableSlamming	bool	true	Impact forces when entering water.
SlammingCoefficient	float	1.0	Slamming intensity. Range: 0.1–5.
SlammingVelocityThreshold	float	5.0	Min vertical speed for slam (cm/s). Range: 10–500.
bEnableExitDamping	bool	true	Damp exit velocity when a hull breaches above the surface to avoid unrealistic ejection.
ExitDampingRatio	float	0.7	Fraction of vertical velocity preserved when exiting. Range: 0.1–1.
Advanced
bEnablePrediction	bool	true	Predict water heights one frame ahead: smoother buoyancy on remote clients.
HeightmapHistorySize	int32	4	Snapshot buffer depth used for prediction.

Blueprint API

Function	Returns	Description
CalculateBuoyancyOutput()	void	Force recalculation.
GetInterpolatedOutput(BodyIndex)	BuoyancyOutput	Per-body interpolated state.
IsInWaterBody()	bool	True if in a discrete water body.
GetWaterBody()	WaterBody	Current overlapping water body.

Delegates

Delegate	Signature	Fires when
OnBuoyancyOutputsUpdated	(UpdatedOutputs : Array<BuoyancyOutput>)	Each time the buoyancy snapshot updates. Recommended hook for swimming, animation, audio.

Multiplayer: BuoyancyOutputs array replicated with RepNotify. bIsInWater replicated. Server calculates, clients receive results.

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PhysicsBodyComponent

UDRW_PhysicsBodyComponent

Purpose: Defines collision shapes (box, sphere, capsule) for buoyancy calculation. Computes total mass, volume, and center of mass.

Attach To: Any actor that needs buoyancy.

Required Components: None (but BuoyancyComponent reads from this).

Properties

Property	Type	Default	Description
TargetComponentName	FName	:	Name of the mesh component to attach shapes to.
MainMaterialType	EDRW_MaterialType	Wood	Default material (determines density).
bEnableWaterInteraction	bool	true	Generate water interaction effects from this body.
Boxes	Array<BoxShape>	:	Box collision shapes.
Spheres	Array<SphereShape>	:	Sphere collision shapes.
Capsules	Array<CapsuleShape>	:	Capsule collision shapes.
bUseCustomCenterOfMass	bool	false	Use shape-based CoM instead of physics engine CoM.
CenterOfMassOffset	FVector	(0,0,0)	Manual CoM offset.
Interaction override
bOverrideInteractionBounds	bool	false	Override auto-derived bounds.
InteractionRadius	float	100.0	Override radius (cm).
InteractionHullLength	float	200.0	Override hull length (cm).
InteractionHullWidth	float	100.0	Override hull width (cm).

Blueprint API

Function	Returns	Description
DebugDrawShapes()	void	Draw shape wireframes.

Shape types

Each shape inherits a common base (Transform, MaterialType, Name, TargetBoneName, bEnableWaterInteraction) plus its own geometry:

• Box: Extents (FVector half-size in cm).
• Sphere: Radius (cm).
• Capsule: Radius and HalfHeight (cm).

A shape becomes “subtractive” (carves volume rather than adding it) automatically when MaterialType = Air. There’s no manual subtract toggle: material drives operation.

Each shape can be additive (contributes volume) or subtractive (hollows out volume, e.g. cabin). Material types include Wood (800), Steel (7850), Aluminum (2700), HighDensityFoam (450), and 30+ others.

See the hull approximation guide for the workflow.

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SmoothReplicationComponent

UDRW_SmoothReplicationComponent

Purpose: Client-side transform interpolation / extrapolation for networked actors. Maintains a state buffer and reconstructs smooth movement on remote clients.

Attach To: Any networked actor with a static-mesh root (vessels, floating objects).

Required Components: None.

Caution

Designed for static-mesh root components with simple physics. Do not use on skeletal-mesh roots or actors with complex multi-body physics setups: the component samples and replays a single transform, which doesn’t represent those cases correctly.

Properties

Property	Type	Default	Description
Core
bEnableSmoothing	bool	true	Master enable.
bUsePollBasedDetection	bool	true	Poll for state changes vs explicit notification.
Timing
InterpolationRelativeTime	float	0.1	Render delay from owner time (seconds). Range: 0–0.5.
TimeSmoothing	float	2.0	Time offset smoothing (seconds). Range: 0–5.
SendRateHz	float	30.0	Expected send rate. Range: 1–120.
bUseHermiteInterpolation	bool	true	Hermite spline for smoother curves.
Lerp
PositionLerpSpeed	float	0.85	Position lerp per frame. Range: 0–1.
RotationLerpSpeed	float	0.85	Rotation lerp per frame. Range: 0–1.
ScaleLerpSpeed	float	0.85	Scale lerp per frame. Range: 0–1.
VelocitySmoothingRate	float	10.0	Smoothing rate for the calculated velocity outputs (per second). Range: 1–30.
Thresholds
ReceivedPositionThreshold	float	0.0	Drop position updates that differ by less than this (cm). Set to 0 to always update.
ReceivedRotationThreshold	float	0.0	Drop rotation updates that differ by less than this (degrees). Set to 0 to always update.
Extrapolation
bEnableExtrapolation	bool	true	Extrapolate when buffer runs out.
ExtrapolationTimeLimit	float	0.5	Max extrapolation time (seconds). Range: 0–2.
ExtrapolationDistanceLimit	float	500.0	Max extrapolation distance (cm).
Snap
PositionSnapThreshold	float	500.0	Snap if error exceeds this (cm). 0 = disabled.
RotationSnapThreshold	float	90.0	Snap if angle exceeds this (degrees).

Blueprint API

Function	Returns	Description
ReceiveNetworkState(…)	void	Feed a new state from the network.
NotifyReplicatedMovementUpdate()	void	Notify that replicated movement changed (poll mode).
SnapToReplicatedTransform()	void	Instant snap.
ClearBuffer()	void	Clear state buffer.
Teleport()	void	Mark next transition as teleport.
GetSmoothedTransform()	FTransform	Current interpolated transform.
IsSmoothing() / IsExtrapolating()	bool	State queries.
GetJitterStats()	JitterStats	Network jitter metrics.
GetInterpolationTime()	float	Current interpolation render-time offset.
GetOwnerTime()	float	Owner-time at the latest received state.

Calculated outputs (BlueprintReadOnly)

These are written each tick and useful for animation / audio / HUD:

Property	Type	Description
CalculatedVelocity	FVector	Linear velocity derived from smoothed transform.
CalculatedAngularVelocity	FVector	Angular velocity derived from smoothed transform.
CalculatedAcceleration	FVector	Linear acceleration.
CalculatedSpeed	float	Linear speed (cm/s).
CalculatedAngularSpeed	float	Angular speed magnitude.

Delegates

Delegate	Signature	Fires when
OnTeleport	(ErrorMagnitude : float)	A snap (rather than smooth interpolation) was applied: useful to gate UI hints or motion blur.

Multiplayer: Client-side only. Does not replicate: reads from replicated actor properties.

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VesselMovementComponent

UDRW_VesselMovementComponent

Purpose: Calculates propulsion, control surface, and resistance forces for vessels. BuoyancyComponent handles buoyancy; this handles everything else.

Attach To: Vessel or VesselPawn.

Required Components: BuoyancyComponent (for water state), a physics-simulating root component.

Properties

Property	Type	Default	Description
CalculationRateHz	float	30.0	Fixed timestep rate. Range: 1–120.
InterpolationStrength	float	0.85	Force smoothing. Range: 0–1.
ForceMultiplier	float	1.0	Global force scale. Range: 0.1–10.
TurnAssistMultiplier	float	1.0	Yaw torque boost. Range: 1–50. Default 1.0 is physically accurate; large vessels often need 5–20.
TrueWindVelocity	FVector	(0,0,0)	World wind for sail calculations (cm/s).
bEnableWindage	bool	true	Air resistance calculation.
WindageFrontalArea	float	0.0	Frontal area for air drag (cm²).
WindageLateralArea	float	0.0	Lateral area for crosswind drag (cm²).
WindageDragCoefficient	float	0.8	Multiplier on computed windage forces.

Blueprint API

Function	Returns	Description
Initialize(VesselData, PhysicsRoot, Buoyancy)	void	Initialize with data.
SetInput(VesselInput)	void	Apply control input.
GetMovementOutput()	VesselMovementOutput	Latest computed movement output (forces, state, lift).
GetMovementState()	MovementState	Displacement, Transition, Planing, or Foiling.
GetPropulsionState(Index, OutState)	bool	Per-propulsion live state (RPM, throttle, thrust). False if index invalid.
GetControlSurfaceState(Index, OutState)	bool	Per-control-surface live state (deflection, lift, stalled).
GetSpeed() / GetSpeedKnots()	float	Current speed.
GetFroudeNumber()	float	Hull Froude number.
IsPlaning() / IsFoiling()	bool	State queries.
SetWindVelocity(WindCmPerSec)	void	Set wind for sails.
GetApparentWind()	FVector	Apparent wind relative to vessel.

Delegates

Delegate	Signature	Fires when
OnMovementStateChanged	(NewState : EDRW_VesselMovementState)	Hull regime changes: Displacement / Transition / Planing / Foiling. Use to trigger audio, FX, camera FOV cues.

Multiplayer: MovementOutput replicated with RepNotify.

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VesselInputComponent

UDRW_VesselInputComponent

Purpose: Enhanced Input handling for vessel control with automatic keyboard / gamepad binding and network replication.

Attach To: VesselPawn or any pawn controlling a vessel.

Required Components: None. Optionally works with VesselCameraComponent.

Properties

Property	Type	Default	Description
InputSource	EDRW_VesselInputSource	AutoKeyboardMouse	Auto keyboard, auto gamepad, auto both, custom config, or custom actions.
InputConfig	VesselInputConfig	:	Custom input config data asset.
InputSmoothing	float	0.0	Analog smoothing. Range: 0–0.99.
DeadZone	float	0.1	Analog dead zone. Range: 0–0.5.
InputSendRate	float	30.0	Client→server send rate (Hz). Range: 1–60.
InputChangeTolerance	float	0.01	Min change to trigger send. Range: 0.001–0.1.
bSendPeriodicFullState	bool	true	Periodic full state for reliability.
Camera
bInvertCameraY	bool	false	Invert Y axis.
CameraLookSensitivity	float	1.0	Look sensitivity. Range: 0.1–5.
CameraZoomSensitivity	float	1.0	Zoom sensitivity. Range: 0.1–5.

Blueprint API

Function	Returns	Description
GetLocalInput()	VesselInput	Current local input state.
IsProcessingInput()	bool	True if input is active.
ForceReplicateInput()	void	Force immediate network send.

Multiplayer: Input is replicated to the server with reliability tuned per signal: frequent analog updates use unreliable channels, zero-input and critical state use reliable. Input is quantized for bandwidth efficiency on the wire.

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VesselCameraComponent

UDRW_VesselCameraComponent

Purpose: Vessel camera with horizon stabilization, speed-based effects, and collision. The boat-camera feel is mostly tuned through the three sub-structs below.

Attach To: VesselPawn or any vessel actor.

Required Components: None. Creates SpringArm and Camera as children.

Note

In this version, only third-person mode is functional. First-person and orbit modes are reserved for a future release.

Properties: top level

Property	Type	Default	Description
ZoomSpeed	float	500.0	Arm length change per second per unit of input.
LookSensitivity	float	0.5	Look input multiplier.
RecenterSpeed	float	1.0	Camera recenter speed (deg/sec).
MinPitchOffset / MaxPitchOffset	float	-45 / 30	Pitch clamp (degrees).
bDoCollisionTest	bool	true	Enable camera collision.
CollisionProbeSize	float	12.0	Probe radius for collision tests.
CollisionChannel	ECollisionChannel	Camera	Trace channel for collision.
CollisionSmoothSpeed	float	10.0	How quickly the camera retracts on collision.
bInvertLookX / bInvertLookY	bool	false	Axis inversion.

Properties: Config (spring-arm geometry)

Property	Default	Description
ArmLength	800	Default spring-arm length (cm).
MinArmLength	200	Minimum on zoom in.
MaxArmLength	2000	Maximum on zoom out.
SocketOffset	(0, 0, 100)	Boom offset from the spring-arm tip (local space).
TargetOffset	(0, 0, 50)	Look-at offset from the vessel (local space).
BasePitch	-15°	Initial pitch on possession.
OrbitSpeed	120	Orbit yaw rate (deg/sec per input unit).

Properties: Stabilization (horizon damping)

Property	Default	Description
bStabilizeHorizon	true	Hold the horizon steady against vessel roll / pitch.
RollDampening	0.7	How much vessel roll the camera filters (0 = follow fully, 1 = perfectly level).
PitchDampening	0.5	Same, for pitch.
StabilizationSpeed	5.0	Stabilization response rate (lower = smoother but more lag).
bSmoothPosition	true	Apply position lag for cinematic feel.
PositionLag	0.15	Position lag (seconds): higher = smoother but more delayed.
MaxPositionOffset	500.0	Maximum position offset (cm) before snapping.
YawFollowSpeed	3.0	How quickly the camera yaw catches up to vessel heading.

Properties: SpeedEffects (FOV / zoom out)

Property	Default	Description
bSpeedFOV	true	Widen FOV with speed for the “fast feel”.
BaseFOV	90°	FOV at zero speed.
MaxSpeedFOV	105°	FOV at MaxSpeedThreshold.
MaxSpeedThreshold	30	Speed (m/s) at which MaxSpeedFOV is reached.
FOVInterpSpeed	2.0	FOV interpolation rate.
bSpeedZoomOut	true	Pull spring-arm back at high speed.
MaxSpeedArmLengthAdd	200	Max additional arm length at top speed (cm).

Blueprint API

Function	Returns	Description
AddLookInput(Input)	void	Feed look input (2D).
AddZoomInput(Input)	void	Feed zoom input (1D).
InitializeForPossession()	void	Reset camera state for new possession.
GetCamera()	CameraComponent	Main camera.
GetSpringArm()	SpringArmComponent	Underlying spring arm.
GetCurrentFOV()	float	Current field of view.
GetSmoothedLocation()	FVector	Smoothed camera world location.
GetSmoothedRotation()	FRotator	Smoothed camera world rotation.

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SeatOccupantComponent

UDRW_SeatOccupantComponent

Purpose: Enables any pawn to occupy vessel seats. Handles seat discovery, occupation requests, and input relay.

Attach To: Any Pawn or Character.

Required Components: None.

Properties

Property	Type	Description
OnSeatEntered	Delegate (Component, Seat)	Fires when occupant enters a seat.
OnSeatExited	Delegate (Component, Seat)	Fires when occupant exits a seat.

Blueprint API

Function	Returns	Description
RequestOccupySeat(Seat)	void	Request to sit in a seat (sends server RPC).
RequestVacateSeat()	void	Request to leave current seat.
FindNearestSeat(Range)	VesselSeat	Find nearest unoccupied seat within range (cm). Default: 500.
GetCurrentSeat()	VesselSeat	Current confirmed seat.
GetTargetOrCurrentSeat()	VesselSeat	Handles replication delay: returns TargetSeat if CurrentSeat not yet confirmed.
IsInSeat() / IsInSeatOrPending()	bool	Occupation state.
GetCurrentVessel()	Vessel	Vessel of current seat.

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VesselPossessionComponent

UDRW_VesselPossessionComponent

Purpose: Enables any pawn to directly possess VesselPawn actors via controller swap.

Attach To: Any Pawn or Character.

Required Components: None.

Properties

Property	Type	Default	Description
SearchRange	float	500.0	Default search range for FindNearestVesselPawnDefault (cm).
OnVesselPossessed	Delegate	:	Fires when controller moves to vessel.
OnReturnedFromVessel	Delegate	:	Fires when controller returns to this pawn.

Blueprint API

Function	Returns	Description
RequestPossessVessel(VesselPawn)	bool	Possess a vessel (sends server RPC).
FindNearestVesselPawn(Range)	VesselPawn	Find nearest unpossessed vessel within range.
FindNearestVesselPawnDefault()	VesselPawn	Uses SearchRange property.

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SurfaceMaskComponent

UDRW_SurfaceMaskComponent

Purpose: Per-actor water surface masking. Creates a proxy mesh for capture and an optional buoyancy mask box.

Attach To: Any actor that should mask the water surface (bridges, docks, platforms).

Required Components: None. Works with WaterMaskingManager.

Note

Surface masking is functional and used in shipped demo content, but is still considered a work-in-progress feature: minor visual glitches at mask edges are possible. File anything you hit on Discord.

Properties

Property	Type	Default	Description
MaskMesh	StaticMesh	:	Mesh defining mask shape.
bEnabled	bool	true	Enable / disable mask.
bMaskBuoyancy	bool	true	Suppress buoyancy in masked region.
bMaskUnderwaterEffects	bool	false	Include in cave mask for underwater shader.
BuoyancyMaskDepth	float	500.0	Depth of buoyancy mask box (cm). Min: 10.
ShapeBuoyancyThreshold	float	0.25	Per-shape coverage to mask. Range: 0–1.
TotalBuoyancyThreshold	float	0.70	Average coverage to mask all. Range: 0–1.

Blueprint API

Function	Returns	Description
SetMaskEnabled(bEnabled)	void	Toggle mask at runtime.

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WaterlineComponent

UDRW_WaterlineComponent

Purpose: Creates a render target-based waterline mask for per-character underwater effects. Useful in split-screen or multiplayer when each player needs an independent underwater view.

Attach To: Player characters or any actor needing individual underwater visualization.

Required Components: None.

Properties

Property	Type	Default	Description
bCanInteractWithWater	bool	true	Whether this waterline contributes to water interaction.
WaterlineCubeMesh	StaticMesh	:	Capture proxy mesh for the waterline boundary.
WaterlineMaskRT	RenderTarget2D	:	Output mask render target.
UnderwaterMaterial	MaterialInterface	:	Underwater post-process material driven by this waterline.

The component initializes itself automatically when its owning actor becomes the local player’s view target: no Blueprint setup required.