Free Electron Documented Operators
Common Operator Info
FE SpineFitOp

blue feedback demonstrates adaptive subdivision


Curves are created to best represent the primitives of an arbitrary surface.

The current role of this operator is to create simulation spines for geometric grass. Further roles will probably involve expansion of the feature set.


Generally, the Input Surface needs to be compatible with the common search algorithms (currently, this requires triangular faces with normals).


A curve is created for each input primitive with a vertex count of Samples. The first vertex of each curve is placed at the first vertex of each primitive. The last vertex of each curve is placed at the further vertex of the primitive. For each sample between the two end points, an initial point is determined by simple interpolation, then that point is moved to the nearest point on the input surface.

The Refinement limits the adaptive subdivision that can control improved curvature in the nearest point algorithms. Increased refinement can affect performance.

An attribute named by Facing will be added to the output curves to provide a rotational alignment. This may be important for binding and wrapping operations further in the graph.

A simplified Fast Snap mode does not use the general search algorithm and should work on any collection of points. However, this mode will only assign output curve vertices to exact point locations of the input surface. If the input surface is coarse, the output curves will be of similar coarseness and it is very possible that some of those output curve vertices will be coincident.


tested in Houdini and Maya

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