[Sidefx-houdini-list] point versus vertex textures ...

Rangi Sutton rangi.sutton at gmail.com
Wed Feb 7 22:12:40 EST 2007

Darran Edmundson wrote:
> A colleague familiar with other tools asked by about the following in
> houdini::
> "I want to create a textured box with smooth normals but with 'faces
> painted' i.e., different UVs at each vertex which are not continuous
> over adjacent faces. The typical textured box then. In other tools
> this can often be implemented as 8 points but with multiple UVs at
> each point (so the vertices generated have to be duplicated). Given
> what I've seen when using the 'Facet' operator, I'm wondering whether
> I need to do this in Houdini or not. But I don't know the typical
> methods of generating UVs like this - I've had a quick go but haven't
> spent a lot of time on it yet."
> His question made be realize that I've never explored vertex texturing
> in Houdini.  My approach would be to use a Facet SOP with unique
> points followed by a UVTexture SOP with faces and point texturing.  In
> this case (where he wants smooth normals anyway), it is obviously
> wasteful in terms of replicating points.  Plus I'd need to massage the
> cusped normals at coincident points on differing faces to be the same.
> When do you use vertex texturing?

Maybe I'm misunderstanding the question. You seem to answer it yourself
when you ask "When do you use vertex texturing". It's when you want to
do what you describe above!

You say ""with other tools"... however Houdini also supports vertex
texturing the same as most other 3d packages. When you first unwrap or
uv project select "Apply to vertex textures" as the type and you're set.
You then have multiple uv co-ordinates for each point. You have a fused
object in 3d, but it appears unfused in the uv viewport so you can map
adjacent faces independently.

Several versions ago Houdini didn't do this and you had to use a facet
sop, or jump through hoops making multiple uv maps. But these days we're
all on board.


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