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[Ed]

Woo hoo - this works now! See 4th (ish?) post below for fixed exporter. If anyone does want a .obj format loader for C#, PM me. You might need to modify it to store textures in however your game stores them, but it might be handy.

Original post:

I got this Sketchup .obj (and .matl) exporter script from here, but it turns out the UV values exported are total rubbish.
Well, they are for a certain style of skinning - namely the traditional games approach of putting all of the texture on a single page and texturing each face with a section of the whole page.

Anyone got any experience working with the Sketchup ruby interface (especially working with texture coords) or a fixed .obj file exporter, or any ideas at all? 

I'll edit in some example data...

Oh, and I can probably post up the exporter and the (C#) code to load .obj/.matl data if anyone's interested in using it themselves, I'll see if it's possible.

[Kaelan]

I would be surprised if you could use sketchup's UV data for texturing purposes, unless you're actually applying your textures in sketchup. The last time I used it the texturing capabilities didn't extend any further than 'make this surface look like brick'.

I suspect that's why the data you're getting looks useless: It probably is.

Maybe try using some unwrap tool to generate UVs for the geometry?

[Ed]

That's what I though until fairly recently. It should be fine though - it certainly can do that kind of texturing internally, it's jus that something is going wrong on export.
Here's an example that I forgot to upload yesterday...



(In case you're wondering, you get this texturing tool by right-clicking on a face and selecting Texture->Position...)

For this model, the texture coordinates come out as:

  vt   0.2500  -0.2500 0.0000
  vt   0.0000  -0.0000 0.0000
  vt   0.2500   0.0000 0.0000
  vt   0.0000  -0.2500 0.0000
  vt   0.0000  -0.2500 0.0000
  vt   0.2500   0.0000 0.0000
  vt   0.2500  -0.2500 0.0000
  vt   0.0000  -0.0000 0.0000
  vt   0.0000   0.0000 0.0000
  vt   0.2500  -0.0000 0.0000
  vt   0.0000  -0.2500 0.0000

...etc. i.e. either 0, -0.25 or 0.25, which is clearly wrong, at least for the "roof" texture which should have a 0.5 in it.

[Ed]

Exporter code fix - just download the obj exporter from the link above, and change lines 598-599 where uq/vq are set to:

Code:

uq = (uvq.x)
vq = (uvq.y)

[I've let the author know as well...]