If your .obj file have no uv mapping, You can generate auto uv mapping when open model. We added "generate UV mapping" option at "open model option" in paint mode.
Added "Export Model" button in paint menu. You can save model that have generated new uv mapping. And you can select "Export MTL and Texture" option. This option will create .obj file, .mtl file, and texture file. If you want to upload model to sketchfab, You will compress these files to .zip. that's all.
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Update Ver0.3.1 Nov/08/2016
Features
-Added "Generate UV mapping" option in open model option panel. If your .obj file have no uv mapping, You can generate auto uv mapping from this option.
-Added "Export Model" button in paint menu. You can save model that have generated new uv mapping.
-Added "Export MTL and Texture" option in export model option panel in paint mode. This option will create .obj file, .mtl file, and texture file. If you want to upload model to sketchfab, You will compress these files to .zip. that's all.
-Added "Release Notes" button in other menu. You can read release notes any time.
Improved
-When showing virtual keyboard, show text inputting onto the keyboard.
Fixes
-Save model with wrong scale when "Export Mesh" in sculpt mode.
note: Features of early access are not stable. These may be changed or abolished.