Differing vertices with UVs?

[Publik]

I made myself a little box to try and learn UVs. It lists as having 3x the verticies and triangles when uploaded. I'm going from Sketchup->Maya for UVs->SL. I've never done any unwrapping before, so I'm really not sure what I'm doing wrong :D Can anyone help me out with this?

And on the subject, has anyone thought of stickying a thread with a good pipeline in it? IE the steps one takes to create a proper mesh?

[Kwakkelde Kwak]

I'm not 100% sure, but I think SL has to double vertices on a hard (UV) edge, try UV mapping the box with one texture and see what happens... edit..oh also the faces, that can't be right.... nvm:)

try using maya instead of sketchup...it's a true pain for mesh as far as I have read on these forums... is the box 12 faces when you upload from maya, but before applying the textures?

 

 

[Publik]

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Kwakkelde Kwak wrote:

I'm not 100% sure, but I think SL has to double vertices on a hard edge, try UV mapping the box with one texture and see what happens...

 

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Right over my head, thought it was one texture :matte-motes-bored:

[Kwakkelde Kwak]

Are you sure it's the UV mapping and not the export from sketchup? People are having tons of weird issues with that...

tripled vertices sounds like disconnected polygons, but that doesn't explain the extra faces...

[Publik]

Nope, have a second copy that doesn't have UVs and it exports better. Still looks to have too many though (24 vs 8)

[Kwakkelde Kwak]

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Publik wrote:

Nope, have a second copy that doesn't have UVs and it exports better. Still looks to have too many though (24 vs 8)

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How do you mean "it exports better"?

As I said, 24 vertices on a cube sounds like all the 6 sides are disconnected, making it 6 squares with 4 corners = 24.

I have worked with maya, but a long time ago and not very long, there should be a way to glue them back together, I'm sure you can find that somewhere in tut or you could wait for the first maya user to read the post. Does this object without UV's also have too many faces?

[Publik]

I think it was how I was doing the UVs, got it back down to 24 vert, 12 tris which is better than the 72 it was at What's strange is that in maya it only shows 8 connected verticies.

[Kwakkelde Kwak]

I'm not 100% sure, but it is possible the hard lines of the box make the vertices double up...I'll have to try that when I have time. Anyway, 12 faces is the way it should be...you could test the very same thing but with a box with 4 polygons per side. If the hard lines cause the vertices to double up, that means it will have 48 vertices instead of 26 (I think).

[leliel Mirihi]

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Publik wrote:

I think it was how I was doing the UVs, got it back down to 24 vert, 12 tris which is better than the 72 it was at

What's strange is that in maya it only shows 8 connected verticies.

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That's because as far as your GPU is concerned a vertex can only have one normal and one coordinate per texture, every sharp edge and every seam in your UV map will create duplicate vertices. So your box that maya shows as having 8 vertices actually has 24, each corner has 3 vertices, one for each of the faces the corner touches. The reason 3d modeling programs merge duplicate vertices is because it's just easier to model like that, and many offline renderers don't have such restrictions.