Check mesh for holes

[FromHell]

Hello!

Is it possible in houdini to check a model for holes or open edges ?

[eetu]

Group SOP -> Edges tab -> Unshared Edges?

[anim]

or Divide SOP with Remove Shared Edges option

then nprims("../divide1") will give you exact number of holes in your mesh

and since the divide will already contain caps for the holes you can just merge it with original mesh and fuse to close those holes (you will need to use reverse right after divide and before merge though to get correct result)

[Erik_JE]

or Divide SOP with Remove Shared Edges option

then nprims("../divide1") will give you exact number of holes in your mesh

and since the divide will already contain caps for the holes you can just merge it with original mesh and fuse to close those holes (you will need to use reverse right after divide and before merge though to get correct result)

Very neat trick.

[FromHell]

thanks guys, that was it!

Tomas, where do I have to put the nprims("../divide1") expression?

Edited January 15, 2013 by FromHell

[zarti]

or Divide SOP with Remove Shared Edges option

then nprims("../divide1") will give you exact number of holes in your mesh

and since the divide will already contain caps for the holes you can just merge it with original mesh and fuse to close those holes (you will need to use reverse right after divide and before merge though to get correct result)

thanks for the tip !

just one note ; if the geometry isnt 'self-enclosed' ( sorry cant find the word in english ) an extra polygon remains . the big silhouete ..

so , it works as you described over a torus , but not exactly over a grid .

.cheers

[anim]

...

Tomas, where do I have to put the nprims("../divide1") expression?

...

anywhere you want

you need to put correct path to divide node, or branch containing primitives created by divide, this expression will simply count them

so for example put it is the switch sop input parameter as a condition like:

nprims("path/to/geo") > 0

it's up to you what you want to do with that information, it will simply tell you if that geo has holes or not and how many if you want. and be careful about what zarti said about open geometries like grid

@zarti: sure, but you cannot consider grid as watertight geometry, so essentially outside border is a hole, you just need to keep in mind how it works

Edited January 16, 2013 by anim

[FromHell]

Hey, thanks for the help.

[frank_13847]

Just to contribute to the conversation, here's another neat way:

- SOP Group with 'Unshared edges' checked

- Loop over connected or named primitive

-Detail wrangle:

int count = 0;

for(int i = 0; i < nprimitives(0); i++)
{
    if(inprimgroup(0, 'edge', i) == 1) count ++;
}

f@count = count;

if(count > 0.0)
{
    for(int p = 0; p< nprimitives(0); p++)
    {
        setprimgroup(0, 'open', p, 1, 'set');
    }
}

 

Cheers!

Edited May 17 by frank_13847

[Librarian]

checkMesh_v003.hipnc