Spring IK | Unreal Engine 5.7 Documentation

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Description

The Spring IK solver uses a verlet integrator to perform an IK solve. It support custom constraints including distance, length etc. Note: This node operates in world space!

Information

Plugin	ControlRig
Category	Hierarchy
Tags	IK
Type	FRigUnit_SpringIK

IO

Name	Description	Permitted Types	Default Value
ExecutePin	This property is used to chain multiple mutable units together	Execute Context

Inputs

Name	Description	Permitted Types	Default Value
StartBone	The name of the first bone to solve	FName	None
EndBone	The name of the second bone to solve	FName	None
HierarchyStrength	Sets the coefficient of the springs along the hierarchy. Values between 1 and 2048 are common.	float	256.000000
EffectorStrength	Sets the coefficient of the springs towards the effector. Values between 1 and 2048 are common.	float	64.000000
EffectorRatio	Defines the equilibrium of the effector springs. This value ranges from 0.0 (zero distance) to 1.0 (distance in initial pose)	float	0.500000
RootStrength	Sets the coefficient of the springs towards the root. Values between 1 and 2048 are common.	float	64.000000
RootRatio	Defines the equilibrium of the root springs. This value ranges from 0.0 (zero distance) to 1.0 (distance in initial pose)	float	0.500000
Damping	The higher the value to more quickly the simulation calms down. Values between 0.0001 and 0.75 are common.	float	0.400000
PoleVector	The polevector to use for the IK solver This can be a location or direction.	Vector	(X=0.000000,Y=0.000000,Z=1.000000)
bFlipPolePlane	If set to true the pole plane will be flipped	bool	False
PoleVectorKind	The kind of pole vector this is representing - can be a direction or a location	Control Rig Vector Kind	Direction
PoleVectorSpace	The space in which the pole vector is expressed	FName	None
PrimaryAxis	The major axis being aligned - along the bone	Vector	(X=1.000000,Y=0.000000,Z=0.000000)
SecondaryAxis	The minor axis being aligned - towards the pole vector	Vector	(X=0.000000,Y=1.000000,Z=0.000000)
bLiveSimulation	If set to true simulation will continue for all intermediate bones over time.	bool	False
Iterations	Drives how precise the solver operates. Values between 4 and 24 are common. This is only used if the simulation is not live (bLiveSimulation setting).	int32	10
bLimitLocalPosition	If set to true bones are placed within the original distance of the previous local transform. This can be used to avoid stretch.	bool	True
bPropagateToChildren	If set to true all of the global transforms of the children of this bone will be recalculated based on their local transforms. Note: This is computationally more expensive than turning it off.	bool	True
DebugSettings	The debug setting for the node	Rig Unit Spring IK Debug Settings	(bEnabled=False,Scale=1.000000,Color=(R=0.000000,G=0.000000,B=1.000000,A=1.000000),WorldOffset=(Rotation=(X=0.000000,Y=0.000000,Z=0.000000,W=1.000000),Translation=(X=0.000000,Y=0.000000,Z=0.000000),Scale3D=(X=1.000000,Y=1.000000,Z=1.000000)))