Sorry if this is old stuff, but I just don’t get it.

When calculating the tbn matrix like it is described in the various examples on the internet, the T and B vectors are computed from the vertex coordinates and the tex coords. For the N vector, there are two alternatives:

- use the vertex normal suppiled by the gemoetry: In this case, the N vector is not orthogonal to T and B,
- compute a normal vector that is ortogonal to N and B: In this case, smoothing does no longer take place.

I cannot find any explanation of how to solve this on the internet. So please anyone help .

Thanks and regards,

Jan