Identify open surfaces

[Mzigaib]

I am sure this is an old issue but I could not find any threads about it.

I am trying to mark or identify open connected geometry with an attribute but I am having failed miserably.

I am trying this but I cant figure out how to mark the whole object soon as if it finds points with less than 3 neighbors, but I think my logic can be flawed.

int npts=npoints(0);

for(int pt=0;pt<npts;pt++){
    int nei = neighbourcount(0,@ptnum);
    setpointattrib(0,"nei",@ptnum,nei);
        if(nei<4){
            setprimattrib(0,"open",@primnum,1);
        }
}

I am running this on primitives in a for each loop, so the idea is if it finds any points with less than 4 connection it should mark the whole connected piece as "open", but it isn't work as I expect I am having some faces in the middle of the connected pieces with different values.

I hope it makes sense.

Any tips?

Thanks in advance.

[Aizatulin]

Hi,

I think an open surface must contain at least one half edge (unshared edge). You can use the group node to get them.

 

 

half_edges_in_geo.hipnc

[Mzigaib]

That is actually a great idea!

I am going to try that.

Thank you dude!

[Benyee]

and there is a little node 'labs distance from border', zero 'radius'

[vinyvince]

measure area non equal to zero?

Edited July 23, 2022 by vinyvince

[Mzigaib]

I think that would work with individual faces but not with connected faces which which is my idea, using groups seems to be working really well.