View Full Version : fbx LW export smoothing errors

01-29-2013, 02:35 PM
Hi All,
i am having a FBX export issue from LW that I hoped you may be able to help with.
I am trying to export a model from layout to use in a live graphics machine called TOG http://rtsw.co.uk/products/tog-3d-pro/

I have exported the scene using the fbx exporter, but when i import into the TOG the smoothing angles are all messed up.
If I re-import the fbx into layout, all the surfaces default to smoothing on and 89 degree angle.
I have been given a link to an fbx converter that autodesk provide, but its not the most intuitive application and I am not the smartest user so we are not making a very successful partnership!
I am on 11.3 Mac based if that makes a difference.

Thanks again

02-04-2013, 01:14 PM
I see the same error in my own custom FBX importer/parser.

Looks like it doesn't really respect material settings .... the only way I could force hard edges was to extract relevant polygons ( cut and paste in place)

02-04-2013, 02:14 PM
Thanks, nice to know its not just me!! ;)
I have been performing an unweld before fbx export to get around it but I imagine that might throw up done other problems somewhere down the line.

02-04-2013, 02:28 PM
If you need it for real-time graphics ( as it looks like you do) then it won't matter , because for real-time rendering (OpenGL , DirectX) this is what is happening underneath anyway.

I have a custom pipeline which ingests FBX files ( mostly from Autodesk products but with LW 11.x from LW as well) and this is exactly what my code is doing anyway ..

Every engine does that - for instance quoting from Unity Manual at http://docs.unity3d.com/Documentation/Manual/OptimizingGraphicsPerformance.html

Note that the actual number of vertices that graphics hardware has to process is usually not the same as the number reported by a 3D application. Modeling applications usually display the geometric vertex count, i.e. the number of distinct corner points that make up a model. For a graphics card, however, some geometric vertices will need to be split into two or more logical vertices for rendering purposes. A vertex must be split if it has multiple normals, UV coordinates or vertex colors. Consequently, the vertex count in Unity is invariably higher than the count given by the 3D application.

When they say that a vertex must be split when it has multiple normals - it is pretty much exactly what you are doing (with cut/paste), since vertices at hard edges require two normals ( pointing in separate directions).
The only potential problem is if you are exporting to another 3d app for some additional processing - sometimes it can cause problems.

And of course, it can be pain in the *** to do that manually ...

BTW.. you don't want to do full unweld because that can easily triple # of vertices and not every engine is smart enough to weld back vertices with the same normals - i.e if it doesn't then your model will look exactly the same in the engine but it will contain way too many vertices which will affect performance.