Class WheelComponent

Wheel node in the powertrain. Applies drive torque, distributes brake torque, and connects to the WheelController for physics simulation.

Inheritance
object
VehicleComponent
PowertrainComponent
WheelComponent
Inherited Members
Namespace: NWH.VehiclePhysics2.Powertrain
Assembly: NWH.VehiclePhysics2.dll
Syntax
[Serializable]
public class WheelComponent : PowertrainComponent

Fields

surfaceMapIndex

Index of the surface in the active SurfaceMap that the wheel is currently in contact with. -1 if the wheel is not grounded.

Declaration
[NonSerialized]
[ShowInTelemetry(NaN, NaN, null, null, 1)]
public int surfaceMapIndex
Field Value
Type Description
int

surfacePreset

The SurfacePreset of the surface the wheel is currently in contact with. Null if the wheel is not grounded.

Declaration
[ShowInTelemetry(NaN, NaN, null, null, 1)]
public SurfacePreset surfacePreset
Field Value
Type Description
SurfacePreset

wheelController

Reference to the WheelController that handles the physics simulation for this wheel.

Declaration
[FormerlySerializedAs("wheelUAPI")]
public WheelController wheelController
Field Value
Type Description
WheelController

wheelGroup

The WheelGroup this wheel belongs to. Set automatically when the wheel is assigned to a group.

Declaration
[NonSerialized]
public WheelGroup wheelGroup
Field Value
Type Description
WheelGroup

wheelGroupSelector

Selector for assigning this wheel to a specific WheelGroup. Used in the editor to organize wheels into axles/groups for differential and brake distribution.

Declaration
public WheelGroupSelector wheelGroupSelector
Field Value
Type Description
WheelGroupSelector

Methods

AddBrakeTorque(float, bool)

Adds brake torque to the wheel on top of the existing torque. The torque is multiplied by the wheel group's brake coefficient or handbrake coefficient. Final value is clamped to the vehicle's maximum brake torque.

Declaration
public void AddBrakeTorque(float torque, bool isHandbrake = false)
Parameters
Type Name Description
float torque

The brake torque to add in Nm. Negative values are ignored.
bool isHandbrake

If true, applies the handbrake coefficient instead of the brake coefficient.
Remarks

Writes the live WheelController field, which Brakes clears at the start of its VC_FixedUpdate. External systems should use Brakes.AddExternalBrakeTorque, which is buffered and applied after the service brake regardless of call order.

ApplyRollingResistanceMultiplier(float)

Applies a multiplier to the wheel's rolling resistance torque. Useful for simulating different surface conditions or temporary effects.

Declaration
public void ApplyRollingResistanceMultiplier(float multiplier)
Parameters
Type Name Description
float multiplier

The multiplier to apply to the initial rolling resistance. Values greater than 1 increase resistance, less than 1 decrease it.

ForwardStep(float, float, float)

Performs the forward pass of torque transmission through the powertrain chain.

Declaration
public override float ForwardStep(float torque, float inertiaSum, float DeltaTime)
Parameters
Type Name Description
float torque

The input torque in N⋅m.
float inertiaSum

The accumulated inertia of all upstream components in kg⋅m².
float DeltaTime

The simulation delta time in seconds.
Returns
Type Description
float

The final torque after processing through all connected components.
Overrides
Remarks

Part of solver pass 2: propagates torque from engine toward wheels. Components apply gear ratios, losses, etc. Returns input torque if no output connected. The engine discards this return value and reads QueryReturnTorque() after the wheels have stepped, so QueryReturnTorque() is the live reaction path; a new node must override that one to be felt upstream.

GetWorldPosition(VehicleController)

Gets the world position of the wheel component.

Declaration
public override Vector3 GetWorldPosition(VehicleController vc)
Parameters
Type Name Description
VehicleController vc

The vehicle controller.
Returns
Type Description
Vector3

Wheel position in world space.
Overrides

QueryAngularVelocity(float, float)

Queries and propagates angular velocity through the powertrain chain.

Declaration
public override float QueryAngularVelocity(float angularVelocity, float dt)
Parameters
Type Name Description
float angularVelocity

The input angular velocity in rad/s.
float dt

The simulation delta time in seconds.
Returns
Type Description
float

The final angular velocity after propagation through all connected components.
Overrides
Remarks

Part of solver pass 1: propagates angular velocity from wheels toward engine. Returns input velocity unchanged if no output is connected.

QueryInertia(float)

Queries and accumulates inertia values through the powertrain chain.

Declaration
public override float QueryInertia(float DeltaTime)
Parameters
Type Name Description
float DeltaTime

The simulation delta time in seconds.
Returns
Type Description
float

The total inertia of this component and all connected downstream components in kg⋅m².
Overrides
Remarks

Adds this component's inertia to downstream components' accumulated inertia. Higher total inertia = slower acceleration, lower = more responsive.

QueryReturnTorque()

Queries the return torque (counterTorque) from downstream components after wheels have been stepped. Called after ForwardStep and wheel SubStep to get fresh counterTorque values.

Declaration
public override float QueryReturnTorque()
Returns
Type Description
float

The accumulated return torque from all downstream components.
Overrides

SetWheelGroup(int)

Sets the wheel group index for this wheel component. This determines which WheelGroup the wheel belongs to for brake distribution and differential connections.

Declaration
public void SetWheelGroup(int wheelGroupIndex)
Parameters
Type Name Description
int wheelGroupIndex

The index of the WheelGroup in the powertrain's wheelGroups list.

VC_Disable(bool)

Disables the powertrain component and resets its operational values.

Declaration
public override bool VC_Disable(bool calledByParent)
Parameters
Type Name Description
bool calledByParent

True if this method was called by a parent component, false if called directly.
Returns
Type Description
bool

True if the component was successfully disabled, false otherwise.
Overrides
Remarks

Zeroes angular velocity and torque so the next enable starts clean.

VC_Initialize()

Initializes the powertrain component and establishes connections with other components.

Declaration
protected override void VC_Initialize()
Overrides
Remarks

Floors inertia at MIN_INERTIA and resolves the input and output links from persisted names.

VC_Validate(VehicleController)

Validates the powertrain component configuration and logs warnings for potential issues.

Declaration
public override void VC_Validate(VehicleController vc)
Parameters
Type Name Description
VehicleController vc

The vehicle controller that contains this component.
Overrides
Remarks

Checks inertia minimum (0.0001) and output connections. Called during vehicle validation.

See Also

WheelController