Free Electron Documented Operators
Common Operator Info
FE GroupOp


A subset of the input surface is assigned to a group.

Membership in groups is not exclusive, so the contents of different groups on one surface may overlap.

This operator is neither a strict subset or superset of the Houdini 'Group' operator, but it serves a similar role. For matching operations, the operators should produce compatible results.


The Input Surface is changed to store membership of elements in groups. An optional Bounding Surface can be used as a distinguishing spatial container.


If Input Groups is specified, those only elements in those groups are considered for the new group. Each space-delimited substring is a pattern to match, optionally as Regex or otherwise using globbing.

A group is created by with the given default Group Name for an Element of either Point or Primitive. If From Attribute is specified, the group name is taken from that string attribute if it exists and is set for a particular point or primitive. In other cases, the default is used, or if that is not set, the element is not added to a group.

Under Bounds, if Enable is on, membership is limited by a bounding Shape which can be a Box, Sphere, or Surface. A box or sphere is defined directly with the Center and Size (width or diameter). The surface mode uses the optional Bounding Surface input. With any of these shapes, the Inverse will choose all the points not inside the shape. For surfaces, Displace Surface will apply Center as a translation and Scale Surface will apply Size as a scaling factor.

There is no dictated behavior for surfaces that are not closed, but a reasonable solution may be attempted.


tested in Houdini and Maya

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