This VOP opens a geometry file and return a list of points with the location P within radius, based on point positions found in Pchannel. Each of the points will be expanded by their RadChannel attribute, which will be dilated by radscale.
Using a radius channel allows intersection detection between spheres of varying radii. In this case you cannot use only your own sphere radius, as the intersecting sphere may have a much larger radius so not be in your search window. Because of this, it is also sensible to use a 0.0 radius with this function just find all the source spheres that your query position is inside of.
Only the maxpoints closest points within the given radius
will be returned. The file name may use the
op: syntax to reference SOP
geometry in the OP contexts. The Pchannel parameter indicates the
attribute which contains the positions to be searched.
The ptgroup is a point group that limits the points to search. This is a SOP-style group pattern, so can be something like
@Cd.x>0.5. A blank string is treated as matching all points.
The radius attribute and radius scale apply to the points being searched, not to the point you are doing the searching with!
If the radius attribute does not exist, this becomes equivalent to