How to get the number of points in a primitive?

[magneto]

I am trying to create a primitive attribute for each primitive in my curve that will store the number of points in each primitive but I couldn't find anything for this in the help.

Any ideas?

Thanks

[zarti]

hi ,

a python script or a foreachSOP are the first things that come in my mind ..

[magneto]

Thanks zarti, I will try the foreach SOP. Was really hoping for an expression function for this

[zarti]

i cannot try it actually , but HOM seems to have something :

http://www.sidefx.com/docs/houdini11.1/hom/hou/Prim#numVertices

.. if you can 'pack-it' like an expression inside an attributeCreate SOP , that should be ( i guess ) .

Edited March 15, 2012 by zarti

[symek]

I am trying to create a primitive attribute for each primitive in my curve that will store the number of points in each primitive but I couldn't find anything for this in the help.

Any ideas?

Thanks

AttributeCreateSOP->Class:Primitive->Value:$NVTX

[magneto]

You amazed me once again How does $NVTX work but $NPT didn't? Don't they count it for the whole object in both cases?

Symek for the president

[graham]

NPT gives you the number of points for the whole geometry while NVTX gives you the number of vertices for the iterating primitive.

[symek]

You amazed me once again How does $NVTX work but $NPT didn't? Don't they count it for the whole object in both cases?

Symek for the president

Don't worry, I always felt like a president (which annoys most people), so I don't have to be one .

As to $NVTX versus $NPT, Houdini, unlike Max for example, strictly separates the concept of point and the concept of vertex. Vertices always belong to and exists with primitives, and as such, are indexed by its membership, not with its number in geometry (which is pretty much useless). So, as you see, $VTX/$NVTX does make sense only for per primitive basis.

[zarti]

@magneto :

ha-ha ! funny because when i read the docs about NVTX-es my atention made a 'ricochet' ( because of minimalistic description there ) from expressions to HOM and stopped there

maybe the same thing happend to you too ( referring to first post ) .

now that i remember , i have used once $VTX to select prims with less than 4 points .. and guess where i found that ? .. on forums

.. and guess who posted that ? im 90% sure it was ..

.. yeah , i too vote for Symek as president , but

he should promise a for Better Houdini Documentation once he gets elected . j/k

[magneto]

Thanks Symek for explaining it. It's more clear to me now.

I don't mind you being a president though. Hell I would even vote for you

EDIT:

@zarti, yeah I like the docs but sometimes I find certain things a little unclear. But that could be because certain Houdini stuff is foreign to me.

Either way if Symek makes commercial videos or books, I am pre-ordering it

Edited March 15, 2012 by magneto

[noWookies]

As a side note, you can find a pretty good run down of verts vs points etc in this doc:

http://files.patrick.janssen.name/2010b/Houdini_Modelling_101_v3.pdf

[magneto]

Thanks noWookies, looks like a good document, reading now