[BUG] FBX Importer broken (binormals/tangeants)
Here is my test inside the UE4 :
As you can see the bug is still here (the mesh named "blender" is correct). From what I know, since Maya 2013 Autodesk changed the way they compute the tangents on their polygonal meshes, which is probably why the UE4 always broke the mesh imported.
This problem also affect the skeletal meshes. If I import a skel mesh and let the editor to compute my normals, I will get a faceted mesh, while if I import my normals I get what I'm expecting (in UE3/UDK my mesh imported was not faceted). Here is the skel mesh if you want to test by yourself : Download "rig_body.fbx".
Build version: 1623704
Install Path: C:\\UDK\\\Rocket\\
Specs: Win 7 x64, 16 GB, GTX 470 (Drivers 301.42), UAC off
--Description : The Editor doesn't read properly the normals/vertices in a FBX mesh exported from Maya 2013 (with the FBX plug-in 2013.1 or even 2013.3) and break the vertices count. (This is also true for Maya 2014.)
--Repro Steps : Download my test mesh (obj file), import it in Maya 2013/2014, export the mesh as an FBX file and import it in the UE4 Editor.
--Expected : The FBX Importer should read properly the vertices count registered by Maya and should import the FBX as it would do with 3DS Max 2012 or Blender 2.63.
--Screenshot : see above for the UE4 bug, see my blog for the UE3/UDK bug.
asked Mar 11 '14 at 03:04 AM in Using UE4
ue4-archive ♦♦ STAFF
I don' think the calculate normals option is broken. Calculate normals uses smoothing groups to find faces that are smoothly connected. The file you provided has 0 for the smoothing group in each triangle which is not a valid smoothing group (Smoothing groups much match at least one bit in a binary AND or else they arent connected. 0 & 0 is still 0). Please note that Maya doesn't use smoothing groups so when you import into Maya it recalculates the normals differently which is why it looks correct in maya. I also have tested this in UE3 and it functions the same way and the mesh comes in faceted. The large vertex count difference is because we cannot share any vertices across triangles when every edge is a hard edge. In this case you get 3 unique vertices per triangle.
I've seen this happen when importing OBJ files without smoothing groups into Maya. Once I export your mesh again with the "geometry->smoothing groups" option checked in the maya exporter dialog, it comes in fine.
answered Mar 11 '14 at 03:04 AM
ue4-archive ♦♦ STAFF
For the difference in vertices I'm guessing that Blender is just welding some vertices together, which your Maya isn't doing by default?
answered Mar 27 '14 at 10:10 AM
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