Hi,

I'm trying to wrap my head around groups and materials.

In Softimage there's clusters (groups of faces), where one can assign shaders too. Removing or adding faces to a group is quite simple, and so change the rendered image.

In Houdini I got so far that I can add a group to a face selection, and create and add a material to the group. I end up witch a bunch of groups with materials applied to them.
So far so good….

What I cannot seem to do is remove or add faces to a excisting group. I tried all dropdown options in the group node, but it seems Houdini doesn't reflect these changes in the viewport.
So I must be doing something wrong, but what?

Also, when I render the object, only some of the faces per shaded group are actually rendered correctly, the rest of the faces stay gray?
So again, I'm probably doing something wrong…

Any help on this is much appreciated!

If this is not the correct way of setting up different shaders on a geo object, I'm all ears for the proper Houdini one ;-)

rob

RobW
Hi,

I'm trying to wrap my head around groups and materials.

In Softimage there's clusters (groups of faces), where one can assign shaders too. Removing or adding faces to a group is quite simple, and so change the rendered image.

In Houdini I got so far that I can add a group to a face selection, and create and add a material to the group. I end up witch a bunch of groups with materials applied to them.
So far so good….

What I cannot seem to do is remove or add faces to a excisting group. I tried all dropdown options in the group node, but it seems Houdini doesn't reflect these changes in the viewport.
So I must be doing something wrong, but what?

you can do it manually removing the faces by number or even combining groups (boolean operations).

RobW
Also, when I render the object, only some of the faces per shaded group are actually rendered correctly, the rest of the faces stay gray?
So again, I'm probably doing something wrong…

check your normals, you should try to refresh them using the facet SOP for example.

RobW
Any help on this is much appreciated!

If this is not the correct way of setting up different shaders on a geo object, I'm all ears for the proper Houdini one ;-)

rob

well, regarding different shader for one single object, I tend to avoid it and have one single object per shader as it is easier to manage a complex scene but that is simply a matter of taste.

For example, you could have a wheel with the tyre, the bolts, the rim, etc… in one single objects but you could separate it and manipulate these independently for both rendering and everything else. Ultimately you will end up using subnetworks to have a clean and meaninful hierarchy like you would probably have in XSI. Specially if you want to have level of detail it is really helpful, therefore I try always to have one object per OBJ node.

Plus houdini drag and drop works on object level rather than SOP level so it is also faster to author your look development this way.

hope it helps.

Hi Jordi,

Thanks for the reply! I'm working my way through your PDF's atm, they're a great help for sure :-)

You're right about the clusters/materials thingy, but sometimes it's handy to have it in the workflow.
Sometimes it's just a pain to import that piece of geometry, and have to break it up into a gazillion pieces to get started on shading. Clusters will be faster at that point.

But if there's a quick way in Houdini to split up face selections on a geo model I'm happy too.

And I tried setting things up again, but even with the facetSOP it doesn't work. I'm getting patches of color, but not the groups with the proper color. Odd…

cheers!

rob

In your Material SOP, it's referencing the group by name and not numbers right? And you're also modifying the group upstream of the Material SOP? What you want to do sounds like it should work to me. It's hard to say what's going wrong.

Can you explain your workflow?

In viewport you can select faces (or any other component) and create group based on that selection, than use Material sop to apply material to specific group. Later you can Reselect for that group in case you need to add or remove more components.