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I'm trying to get a high, medium and low poly version of a mesh working in my game, using the same diffuse and normal map texture. However my models don't maintain their UV coordinates when using Decimate modifier.

I'm very new to Blender but I've created an Asteroid object using Subdivision surface plus Displace modifier.

I apply these modifier once I get the shape I want and then use the sculpting tool to make a few modifications.

I have a rock texture which I set to a high X and Y repeat. It also has Coordinates set to Generated and Projection set to cube. When displaying in Rendered view it looks ok.

So I have a very high level source model with over 300,000 faces. In edit mode I select everything an do Smart UV Project. In the UV/Image editor I see the polys mapped to the texture.

I then use the Bake option to render out the high resolution diffuse map.

I duplicate the object and use the Decimate to reduce it down to 60,000 polys and Bake a normal map using the 300,000 poly version.

I then duplicate it again and create 10,000 poly and 500 poly versions.

However then I create materials that use the baked diffuse and normal maps they don't map correctly any more. It seems Decimate doesn't keep the UV's.

So how an I do this in Blender? I need to take a very high res model and create multiple levels of a mesh but use the same diffuse and normal map.

What am I doing wrong?

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    $\begingroup$ Sounds like a good use case for a multi resolution modifier. That said, since you are using smart UV unwrap, could you duplicate the object, apply the modifier, and re-unwrap for each detail level? $\endgroup$ – gandalf3 Oct 20 '14 at 20:49
  • $\begingroup$ @someonewithpc Actually the decimate modifier does preserve UVs. $\endgroup$ – gandalf3 Oct 20 '14 at 20:57
  • $\begingroup$ @gandalf3 then what's the point of the question? $\endgroup$ – someonewithpc Oct 20 '14 at 20:59
  • $\begingroup$ @someonewithpc How should I know!? ;) $\endgroup$ – gandalf3 Oct 20 '14 at 21:01
  • $\begingroup$ @gandalf3 I could remap each lod, but I would need separate diffuse and normal map textures for every lod which is a bit of a waste of memory. $\endgroup$ – Martin Oct 20 '14 at 21:07

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