Hello All
Usually I use Sopcreate for my workflow, but this time, I try to use the Component builder and I have a problem :

I'm used to create an "attribute create" node to specify which object should be subdivide and wich is not.
Then, in lop context, I just check "USD Custom Attributes" and type "subdivisionScheme" and everything works fine (like in my two screencapture bellow).

But, if I use the component builder, there is no "USD Custom Attributes"...

When I leave my mouse on top of "Treat Polygons as Subdivision Surfaces" it says "Any polygon meshes not already tagged as subdivs, set the subdivisionScheme to 'catmullClark'."

But how can I tagged as subdivs ?

I'm just wondering, what is the advantage of this approach over immediately doing a subdivide in SOP?

philippepetitpas
But, if I use the component builder, there is no "USD Custom Attributes"...

When I leave my mouse on top of "Treat Polygons as Subdivision Surfaces" it says "Any polygon meshes not already tagged as subdivs, set the subdivisionScheme to 'catmullClark'."

Hmm it seems the way the componentbuilder HDA is constructed makes it hard to have a mix of subdiv and mesh geometry. The good news is that the component builder is just an HDA using a sopimport, so you can unlock and jump in and enable "USD Custom Attributes" on node "base_geo" and it should work. The other limitation I spotted is that the component builders internal sop network overrides the __subdiv__ primitive group, which is the other mechanism sopimport uses to determine which faces do/don't get catmullclark subdivision.

RGaal
I'm just wondering, what is the advantage of this approach over immediately doing a subdivide in SOP?

A subdivide sop just applies one or more iterations of subdivision to a polygon mesh. In the end you will still have a polygon mesh though, which is now heavier and still may not be smooth enough depending on camera angle etc.

A subdivision surface on the other hand is perfectly smooth, kind of like if an infinite number of subdivision iterations had been applied. Given a subdivision surface at render time, Karma figures out how many polygons to use to approximate the surface smoothly based on the camera position/angle. Every face will get diced into small pixel-size micro-polygons based on its size on screen and so always look perfectly smooth.

Another advantage of subdivision surfaces is you don't need to generate normals - subdivision surfaces generate perfectly correct and smooth normals automatically.

Yeah Component Builder is intentionally simple/broad. Usually what I've seen is people do when they need mixed subdivs/meshes, is to append an Edit Mesh LOP [www.sidefx.com] after Component Geometry, to mark their subdivs. In the Scene Graph Tree, if you RMB on meshes, you can select Edit Primitive with New Node, which will create a Mesh LOP in edit mode.

You could also set osd_schemeSOP Attribute to define which parts are subdivs. We'd like to make this easier in a future release, but see this doc here for more info about the prim attributes: https://www.sidefx.com/docs/houdini/solaris/sop_import.html#subd [www.sidefx.com]

Thank you all for the moment I use the « edit mesh » solution