[Bf-committers] [Bf-blender-cvs] SVN commit: /data/svn/bf-blender [51258] trunk/blender: Cycles: Anisotropic BSDF enabled, with tangents now computed from the active UV map.

[Brecht Van Lommel]

Hi,

Replying a bit late because it seems this mail only just got through.

> On Thu, Oct 11, 2012 at 12:44 PM, Morten Mikkelsen <mikkelsen7 at gmail.com>wrote:
>
>> For aniso lighting computing tangents at vertex level is a total dead-end.
>> Not the way to go.
>> You want to compute the tangents at pixel level from the underlying
>> parametrization chosen.
>> It's the best way to significantly reduce the impact of the inherent
>> singularities which completely destroy the per vertex averaged tangent.

Ok, I can see we have an issue with singularities, but using
mikktspace does not seem ideal for anisotropic shading. There's still
many cases where you can line up the tangents quite well at UV seams
even if the UV's are not connected, because the tangent can still
match. Also at the the top of a UV sphere you can still get smooth
results if you average with two neighboring triangles, but not the
ones on the other side.

As I understand it mikktspace is based on comparing UV coordinates,
whereas we should actually be deciding merge/nomerge based on the
difference between tangents in UV space, with some threshold. I hope
that's accurate, correct me if I'm wrong.

Thanks,
Brecht.