Weird tangents and binormals computation

Pipeline
1

Hey, I have some serious problems with the generation of tangents and binormals, I’m doing .dae => .egg, then I compute tangents and binormals with egg-trans.

I have this :

normals

binormals (seems to follow uv)

In the .egg file, it looks like the binormals and tangents are attached to the UV, why ?

<Vertex> 3228 {
        -2.366 5.694 0.477
        <Normal> { 0.073 0.049 -0.996 }
        <UV>  {
          0.932 0.226
          <Tangent> { 0.996 0.070 0.061 }
          <Binormal> { 0.258 -0.966 -0.016 }
        }
      }
2

Tangent and binormal are calculated using UV (texture coordinates), so it’s no surprise it’s stored under UV. If you had many texture coordinates, you would have multiple tangent and binormal vectors too. One set for each UV set.

In the same way, it’s also no surprise that the vectors follow the texture coordinates.