Compute tangent face per fragment & tagents and binormals

CVee

Hello,

So I'm getting into substance painter for the 1st time and I was introduced to this new term: "compute tangent face per fragment ". Now I have found some places online explaining what this is though, I don't really fully understand it and have to do more reading.

To give some backstory I'm making a character in 3ds max and wanted to export it into a .fbx to put it into substance painter, and then render it all in 3ds max. I am not going to be using nothing like Unreal or Unity (since people online talk about these programs when talking about this topic).

What I want to know, and can't find out is:

In 3ds max when turning the character into .fbx should I enable "tangents and binormals"?
And how about in Substance Painter? Should I enable "compute tangent face per fragment"?

musashidan

If you're rendering in Max then it doesn't matter as you're not syncing the bake/destination via mikkt tangent space. You would only uncheck t/b-n in .fbx and check compute tangent if you want SP/UE/Unity to compute the normals using mikkt.

But in my experience if baking to render in Max it shouldn't matter as I've always got good results. Just make sure to follow all the usual rules for baking NMs.

Kedong

musashidan said:

You would only uncheck t/b-n in .fbx and check compute tangent if you want SP/UE/Unity to compute the normals using mikkt.

Hi musashidan, if both baking software and renderer compute the normals using mikkt, I don't think export tangent and binormal of the mesh is necessary. Quote from Substance Painter Documentation: "When using Substance Painter maps with UE4 where the normal is baked in Substance Painter, it's best to use an FBX that does not contain tangents. " https://support.allegorithmic.com/documentation/display/SPDOC/Unreal+Engine+4