Rob Chapman

this does not work as of houdini 20.5.445 production build Ive done all that said above, toggled compute / import on the FBX options in unreal I never get smoothing groups to arrive am using ROP FBX character output if that makes a differnce?

Hah I feel your pain!

according to this page:
sidefx to unreal docs [www.sidefx.com]


unreal_face_smoothing_mask > attribute name
prim > attribute class
int > attribute type

should = Mesh smoothing mask data if int set 1.

of course it doesnt work! setting vertex normals doesnt either and ticking compute smoothing groups on / off doesnt either.

other posts says it doesnt matter. but still! if it says it should work then it should

After much further digging its the UV's causing the problem, deleting all UV attributes then problem goes away. so definately its an issue with Unreal engine 5.4 inmport end of the equation. Its a funny old game to get increasing vertices (points) every iteration doing a round trip from houdini > unreal > Houdini > unreal again. different settings with smoothing groups and various import FBX options with creating or not normals and tangents gave varying vertex count results, but this is an Unreal problem. normally(ha get it?) its not an issue for just an exported skeleton mesh to work as is, but in this case I needed the skeleton mesh vertices count to match EXACTLY another exported alembic file from Houdini, to train the ML Deformer correctly

so the training worked in the end ONLY if I made the alembic file from a point deformed version of the skeleton mesh via Houdini > Unreal > Houdini. it doesnt work from the orig Houdini export as the vertices ID number is different also so the deltas were WAY out of whack.

Happy days