Documentation / Node reference / geo nodes

geo/AttributeExpand

Writes a float point attribute that expands from a group: a weight falling off with the distance along the mesh, or that distance itself.

Attributes

geo/groupExpand grows a group by rings, so a point is either in or out. This node measures instead. Every point gets its distance from the group, walked along the connected points with each connection's real length, so the distance follows the surface and never jumps across a gap. It then writes either a WEIGHT, 1 on the group and falling off to 0 at the radius (the same ramp geo/softTransform uses), or the DISTANCE itself, unbounded, for a geo/PointBuilder to remap any way it likes.

The use it was built for is weighting regions on a mesh from selections rather than from painting: a geo/groupCreate per region (a sphere or a box around the jaw, the brow, the back of a head), an attributeExpand per region writing its own attribute, and a geo/PointBuilder that pushes or scales each region by its attribute. A selection survives a change of topology; a painted attribute does not.

A primitive group is resolved to the points its primitives touch. Points the walk never reaches, in a disconnected piece or past the radius, get a weight of 0, and a distance of -1 in DISTANCE mode. The walk follows the mesh edges (and the diagonals inside a quad), so on a coarse grid it slightly overestimates the true surface distance; a finer mesh brings it closer. An object on which the group has no point gets the attribute all unreached, so the stage carries it uniformly; the node errors only when the group has no point on any object, or when the group is left empty. Geometry with no point buffer (a solid, a volume, a field, a NURBS net) is skipped with a warning.

Parameters

Name Type What it does
group String The point or primitive group to expand from. Its points are at distance 0 and get weight 1. An object on which it has no point gets the attribute all unreached.
attribute AttributeName The float POINT attribute to write. It is created when missing and overwritten when present.
output UInt8 WEIGHT · DISTANCE WEIGHT writes 1 on the group falling off to 0 at the radius. DISTANCE writes the distance along the mesh from the group, in world units, with no cap.
radius Float How far from the group the weight reaches, measured along the mesh. At the radius and beyond the weight is 0.
falloff UInt8 SMOOTH · LINEAR The shape of the ramp from 1 to 0. SMOOTH eases in and out; LINEAR is a straight line.

Examples

Scenes you can open in the editor that teach this node.

See also

This page is generated from the engine, so it describes the release you can download. The same text is in the editor's Help panel next to the node itself.