Hi all,
My question might be quite obvious but, does houdini support vertex normals? How do I calculate them?

thanks
kuba

Mantra supports vertex normals. So you can for example use Facet SOP, Edge Cusp SOP or something else to create hard edges and then promote N as vertex attribute onto original geometry. Mantra will use it. Yep, a bit painful workflow.

Not that I wish to rub salt into anyone’s wounds but isn’t it so that until vertex normals in OpenGL are supported Houdini won’t be reasonable to use in a game production. I know that it has been used several times before but the fewer amounts of vertices that have to be calculated the better right? Cusping edges for real-time doesn’t seem to be a good option in those cases.

It was my understanding that even in applications that support vertex normals by the time you export for engine you're still going to be drawing a separate point for each varying normal. In these cases Houdini would be more representational of the data that gets drawn then.


—- edit —–

which isn't to say that the whole working with normals thing in Houdini is somehow better or easier…

photex
by the time you export for engine you're still going to be drawing a separate point for each varying normal.

I´m not sure about that though. Having double points for skinned objects doesn’t really make sense for optimized performance either. If you take the .obj format and open it up as a text file you’ll find the same point count as you had in the source app and an accompanying “vn” attribute for each vertex normal. But it might be as you say that some engines do it that way.

It's definitely per engine in terms of how they like their data cooked.

I also wouldn't consider the obj format a great representation of how data will be organized for a game engine.

I asked this question of a Gamebryo engineer recently in concerns to how their mesh data is handled. The answer I got was that if you have a hard edge, you really have two edges. I couldn't really get into details, but I was told that meshes are highly optimized per platform so it can depend on that as well as whether this was an actor or static mesh, pc or ps3, etc etc.

I guess you’re right photex. I’ve recently started working in a game company where we have a custom exporter from Maya to the game-client. And it is doing a split upon export.