MergeSmoothing is a windows program that will read an FBX file and generate smoothing groups based on the normals of the mesh. It can read in earlier FBX versions and will output a 2013 FBX file. The UDK game editor wants smoothing groups and it wants version 2013 files. If both conditions are not met it will generate a warning message. This program works best with Lightwave version 11.6 and up. Right click the link above to download the executable.
April 8 2014:
Import from... - this is the FBX file that lacks smoothing groups
Export to ... - the output file that will be a copy of the input FBX file but with smoothing groups included
Execute - press this button to make it all happen.
Lightwave 11.5 will export vertex normals based on the surface smoothing. Modeler still only exports smooth normals so layout is the better option for exporting fbx meshes. If the mesh is all hard edges all the smoothing group indices will be 0. If the mesh is all soft edges all the indices will be 1. Combinations of soft and hard edges will have indices starting at 0 and counting up as needed.
MergeSmoothing was written for FBX files generated by Lightwave v11. It won't work with Lightwave 10.1 directly, because the vertex normals are all "hard". This is the reason for the "Import smooth..." option. However, the normals can be made soft in the resulting file by exporting to an FBX text format file and changing the smoothing group from all zeros to all ones with a text editor.
February 2014: Test with LW(v11.6) shows that proper normals are now exported by both modeler and layout. UV restrictions have also been removed.
Here is what the result of Lightwave10.1 file with smoothing groups generated for it:
LayerElementSmoothing: 0 {
Version: 102
Name: ""
MappingInformationType: "ByPolygon"
ReferenceInformationType: "Direct"
Smoothing: *6 {
a: 0,0,0,0,0,0
}
Smoothing groups start at the number 1 so changing the 6 0's to 1's would make the 6 polygons in this mesh have the same smoothing group. Actually, any number up to 32(I think) can be used. If the numbers are all the same you get smoothing across those polygons.
LayerElementSmoothing: 0 {
Version: 102
Name: ""
MappingInformationType: "ByPolygon"
ReferenceInformationType: "Direct"
Smoothing: *6 {
a: 1,1,1,1,1,1
}
Source Code - download/MergeSmoothing_src.zip