Hi guys! Having lots of fun with Houdini lately

How do I go about grouping/selecting only those points (or those edges) that are the outer boundary of a primitive?

Thanks!
Gon

Manually, assuming points are fused, loop-select (shift-L) should do. Otherwise you can try to build simple VOPsop to store neighbours count in a new attribute. In the next step use expression in groupSOP to select those points which have attribute value less or equal 3. Example attached.

You can also use the groupSOP and set it to select points and “unshared edges” on the Edges tab.

Hi Georg, hi Kuba,

thanks so much for the answers, yet in Kuba's VOP SOP (in which I nevertheless learn allot!) it doesn't work in all cases (i.e. points that have 4 neighbours can be border points too) and in Georg's GROUP SOP it just doesn't do it (even though I have a CLEAN and a FUSE prior in the network)…

What to do? Wouldn't it be interesting to write such a SOP in the main library?

What I did for now is to use AttribTransfer from the primitives at the other side of the border to spill over and colour the border points, then I group-select by colour.

Thanks for your time!
Gon

hm.
well.
It always depends on your geometry …