Here's a fix for a pet peeve of mine... TBN generation.
Calculating tangents and bitangents(binormals, lol, the uneducated) worked fine, until you got a mesh with mirrored (or backward) texturing, then it got a bit funky.
The reason for this... a couple.
First, when determining the texture orientation, a single test was done. This would break if a texture was mirrored on one axis (including if the whole texture was mirrored). this has been broken into 2 seperate tests, the original test (u) and it's opposite (v). Try this test with your fingers - make a 3-axis formation (remember right hand rule?) and then try the cases out (+uv, -uv, +u-v, -u+v) - you'll need to break at least one of your fingers to visualise half of the results... so fixed.
Second. although the small fix helped, it still generated broken TBNs (half left handed, half right), so, a simple test for handedness is performed and the bitangent is recalculated from the cross of the vertex normal and the (corrected) tangent.
Now imported meshes look groovy, you no longer need to correct the TBN and normal maps are easier for the artist to make (you can put down the cape of +10 artistic normal mapping skill, it looked silly anyways).
Ok, it's not 100% optimal, but it works.
anyways, do what you will with the patch (You're welcome).