Bone Group · Region

Baseline: OverAnim 0.1.0 Beta · Unreal Engine 5.8
Headers: OverAnimation/Asset/OverAnimBoneGroupDesc.h, OverAnimation/Types/OverAnimRegionTypes.h

FOverAnimBoneGroupDesc represents one Region and that Region's Module Stack. Bone Group is the structure authored in Details; runtime Bone Group instances are not part of the public integration surface.

FOverAnimBoneGroupDesc

Details UI Name	C++ Property	Default · Range	Effect · Relationship
`Group Id`	`GroupId`	GUID for each new Group	The Notify's `BoneGroupIds` uses this identifier. Do not change it manually except through duplication or deletion.
`Group Name`	`GroupName`	`None`	A Response Rule's `BoneGroupName` route uses this value. It must be unique within the asset.
`Always Active`	`bIsAlwaysEnable`	`false`	Keeps the Region active without a Response/Activation Window. Disable it for response-only Regions.
`Affected Bones`	`AffectedBoneGroup`	Empty array	The skin weights of these bones form the basis of the Region mask. Root/Leaf expansion is applied after this array.
`Expand Toward Root`	`ExpandTowardsRoot`	`0`, `0+`	Adds parents of each Affected Bone up to the specified depth.
`Expand Toward Leaves`	`ExpandTowardsLeaf`	`0`, `-1` or `0+`	Adds descendants of each Affected Bone. `-1` includes the entire descendant branch.
Region Mask	`MaskPolicy`	Structure defaults below	Defines vertex-weight falloff and the 0/1 ranges.
LOD Policy	`LodPolicy`	`WarnIfInactive`	Determines whether missing Region influence bones at the current LOD are allowed, warned about, or required for coverage.
`Region Camera Readability`	`ViewStylization`	Enabled, importance `1`	Per-Region permission and strength for Camera Readability. Used together with the Component's master correction.
`Action Group`	`AutomaticActionGroup`	`None`	Under `Analyze Any Active Animation`, selects one Region among those with the same name. Under `Only Selected Animations`, shares one detected Stage among matching Regions. An empty value makes the Region independent.
`Analyze Animations`	`AutomaticPhaseAnimationRouting`	`Analyze Any Active Animation`	Selects Animation routing for Automatic Stage. See the enum table below for each value's contract.
`Allowed Animations`	`AutomaticPhaseAnimations`	Empty array	Displayed only for `Only Selected Animations`. Every Animation must also be in the Asset's `AppliedAnimations`.
`Authored Stage Curve`	`AuthoredMotionPhaseCurveName`	`None`	Optional six-stage curve. The integer portion is the Stage and the fractional portion is Stage progress. Takes priority over Markers and automatic analysis.
`Authored Curve Blend Weight`	`AuthoredMotionPhaseCurveWeightName`	`None`	Companion curve that removes animation blend-weight attenuation from the Stage Curve. A validation error occurs if no Stage Curve is set.
`Analysis Method`	`AutomaticActionMotionAnalysis`	`Primary Chain (Recommended)`	Automatic Region motion analysis scope used when Fixed Analysis Bone is empty.
`Fixed Analysis Bone`	`MotionSampleBone`	`None`	Optional fixed reference bone. If `None`, `Analysis Method` resolves an analysis bone or weighted chain.
Module Stack	`Modules`	Empty array	Array of instanced `UOverAnimDeformerModule` objects. See Effect Modules.

FOverAnimRegionMaskPolicy

Details UI Name	C++ Property	Default · Range	Effect · Relationship
Falloff Mode	`FalloffMode`	`SmoothStep`	Selects the mask-weight curve from `Linear`, `SmoothStep`, and `Power`.
Zero Weight	`ZeroWeight`	`0`, `0..1`	The Region effect is 0 at or below this skin weight.
Full Weight	`FullWeight`	`1`, `0..1`	The Region effect is full at or above this skin weight. Must be greater than `ZeroWeight`.
Falloff Exponent	`FalloffExponent`	`1`, `0.01+`	Curvature of `Power` falloff. Other Modes retain the UI value but do not use it in the result.

Region Enums

Enum	Value	Meaning · Compatibility
`EOverAnimRegionFalloffMode`	`Linear`	Linearly interpolates between 0 and full.
	`SmoothStep`	Smooth interpolation at both ends. This is the default.
	`Power`	Changes the weight distribution using `FalloffExponent`.
`EOverAnimRegionLodPolicy`	`AllowInactive`	Allows the Region to have no coverage at this LOD. The effect may not be visible.
	`WarnIfInactive`	Reports insufficient coverage as a warning.
	`RequireCoverage`	Missing coverage is contractually incomplete. Attachment dependencies require coverage regardless of this policy.
`EOverAnimRegionCompositionPolicy`	`AdditiveClamped` (`Additive Delta`)	Adds overlapping Region deltas and constrains them to the safety range.
	`StrongestDelta` (`Strongest Delta`)	Selects the single strongest delta at each overlapping position.

Automatic Region Motion Enums

Enum	C++ Value	Editor UI	Meaning · Compatibility
`EOverAnimAutomaticActionMotionAnalysis`	`PrimaryGuideChain`	`Primary Chain (Recommended)`	Analyzes a connected chain of explicit Affected Bones and excludes helper branches. A usable chain requires at least two bones.
	`AllAffectedBones`	`All Affected Bones`	Analyzes all affected motion across multiple branches. Intended for specialized multi-branch actions.
`EOverAnimAutomaticPhaseAnimationRouting`	`Automatic`	`Analyze Any Active Animation`	Does not restrict active Animations; Regions in the same Action Group compete.
	`SelectedAppliedAnimations`	`Only Selected Animations`	Shares the detected Stage among Regions on the same route when the current Animation matches `Allowed Animations`.
	`Disabled`	`Do Not Analyze Automatic Stages`	Does not perform automatic stage analysis for this Region. Gameplay Signals and Notifies have separate contracts.

Stage timing priority is Authored Stage Curve > OverAnim Motion Stage Marker > Animation routing/automatic analysis. Resolved Analysis and Phase Timing Priority in the Details customization are editor-only rows that display this resolution; they are not serialized properties.

FOverAnimRegionViewStylizationSettings

Details UI Name	C++ Property	Default · Range	Effect · Relationship
`Allow Camera Readability Correction`	`bEnabled`	`true`	Allows this Region to receive camera correction. It does not operate when the Component's `Enable Camera Readability Correction` is disabled.
`Region Readability Strength`	`Importance`	`1`, `0..1`	Per-Region multiplier for depth-action reveal and screen-thickness protection. It does not create deformation when there is no active Module response.
`Action Direction Used by Camera`	`ActionAxisSource`	`Automatic`	Source of the action direction used by the camera to identify hidden depth motion.

EOverAnimViewActionAxisSource values are Automatic, ActiveResponse, SourceMotion, SimulatedGuideMotion, and PoseChain. Automatic selects the first available direction in this order: active response, source animation motion, simulated guide motion, then current pose chain.

Region names and IDs

Response Rules route by GroupName and ModuleName, while the OverAnim Bone Group Control Notify uses GroupId, which is an FGuid. Renaming does not change the Notify's target ID, but the Rule route must be updated to match the new name.