by Vectrotek » Sun Apr 23, 2017 3:04 pm
If you animate a mesh with bones, then you HAVE TO update the Tangents AND Binormals
because the absolute position of vertices (upon which T's and B's rely) in a triangle
"changes" at every frame. Matrices handle the rotation and scaling of WHOLE objects just fine, but,
again, Skinning and deforming character limbs complicates things somewhat.
Also, crossing the Tangent with the Normal in the shader, to get a Binormal whether Vertex or Fragment
will not work because to get the the CORRECT Bi-Normal a different vertex of the Tri, i.e. vector has to be read
which cannot be done during any action inside the shader.
Now, unless there has been some significant architecture changes in graphics hardware
which I don't know of, then I'm afraid this is how it is.
Anyhow, only when you look "real closely" at Specular Highlights in Skinned Objects using Normal Maps, then
the "Physical Error" brought about by animation and "bogus" Binormals will be noticeable.
But, let me add, there are very few software titles out there that has truly addressed this problem,
not even Doom MMXVI. In fact I've never seen any Game or 3d App that does this successfully!
Anyway, these things really only become important if you are using Normal Maps on your objects
and real time lights in the scene.
Anyhow I've deliberated on this at length in previous posts which you probably did not look at yet.
Anyway, I hope to be upgrading my system really seriously soon..
Currently busy with studies.. Living day by day..