I hope this one will be usefull for creators of 3D models for game,quick explanation what are NULLs for those who dont knew what they are:NULLs are used to keep smoothing between two separate meshes so model dont look ugly ie: wings,they are build from 2 separate parts but we cant see those parts as separate only as one object, NULLs are needed only for 3D model,game dont use them,thats why we need remove them from our exported model.
This tutorial explain how to build meshes with NULL parts,for main meshes D0,D1,D2,D3 ,LODs dont need them.
As example i use WingLIn,its complete left wing not cut in half,it has only one material applied Gloss1D0o (ID1).
Change number of materials via material editor to 2 or more if need(multimaterial mesh)and name it NULL or delete,whatever.
Select faces from the part of mesh they will be NULL material and change their ID to 2 or ID X of last material u set with material editor.Its important .
Now we export our mesh with Fatduck exporter,we can see two materials Gloss1D0o and NULL(delete)
Now the funny part
removing NULL part of mesh,idea is to delete all vertices,mapping coordinattes and faces for this material,sounds scarry, dont worry its easy using Notepad2 or any other text editor wich show you numbers of lines in text, and with little help of windows calculator is even easier,its simple math to do.Just count number of lines they need to be deleted for each group of numbers,ie: in this case its 65 lines for verts and mapping coordinates and 70 lines for faces.
[Materials]
Gloss1D0o
NULL this can be removed
[FaceGroups]
257 245
0 0 192 0 175
1 192 65 175 70 we need to remove 65 verts,65 mapping coordinates and 70 faces for the last material
after we do this we can delete from [FaceGroups] this 1 192 65 175 70 and correct main vertices faces numbers from 257 245 to 192 175
and at the end we have something like this
[Materials]
Gloss1D0o
[FaceGroups]
192 175
0 0 192 0 175
For meshes with more than one material,mostly fuselage,tail,keel,wing with Ovelay materials do it same way,only when calculate new main verts/faces numbers use values from the last material.Here is proof it works in game ,same wings prevoiusly without NULLs and after i added them.