Bone Driven Controller

Describes the Bone Driven Controller node which allows a 'Driver' bone to dynamically affect the motion of one or more 'Driven' bones.

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The Bone Driven Controller allows a "Driver" bone to dynamically affect the motion of one or more "Driven" bones. This is useful for characters that have accessories attached as you can use this to avoid geometry from intersecting during an animation, even when a lot of blending is being used.

You can either set the "Driver" value directly with a Multiplier , remap it to a whole new range, or use a Curve asset to drive the motion. Using a Curve is usually the best approach as it lest you define the response naturally and interactively tweak points/tangents while seeing the changes reflected in real-time.

In the example below, the attached accessory (green) has no authored animations, and is being driven in two axes as a function of the character's thigh bone. This is all calculated at runtime, so a blend of animations ends up working quite well here, even without hand-authored tweaking.

Property

Description

Source (Driver)

Source Bone

The Bone to use as the controller input.

Source Component

The Transform component to use as input.

Mapping

Driving Curve

Curve used to map from the source attribute to the driven attributes if present (otherwise the Multiplier will be used).

Remap Source

Whether or not to clamp the driver value and remap it before scaling it.

Multiplier

Multiplier to apply to the input value (Ignored when a Curve is used).

Destination (Driven)

Target Bone

Bone to drive using controller input.

Target Component Space

The Parent Bone Space used.


Value	Effect
Translation	The XYZ component of translation on the target bone.
Rotation	The XYZ component of rotation on the target bone.
Scale	The XYZ component of scale on the target bone.

Modification Mode

Set the type of modification to make to the destination component(s).


Value	Effect
Add to Input	Add the driven value to the input component value(s).
Replace Component	Replace the input component value(s) with the driven value.
Add to Ref Pose	Add the driven value to the reference pose value.

Settings

(As Pin) Alpha

Enable/Disable the display of the Alpha pin on the node.

Alpha Scale Bias

Set the minimal and maximal input scaling values.

Bone Driven Controller nodes are also affected by the LOD Threshold system introduced in 4.11. You can find the setting for this in the Details Panel for the Bone Driven Controller node.


Property	Description
LOD Threshold	This is the max Level of Detail (LOD) that this node is permitted to run on. For example: if you have LOD Threshold set to 2, it will run until LOD 2, but disable itself once the component's LOD becomes 3.