textangent vs tangent

Two of the export options in OpenCollada are (a) “exportTexTangents” and (b) “exportTangents”.

Can someone please explain the difference between “texTangent” and “tangent”?

I am quite familar with the concept of tangent space as used in normal mapping. My guess is that for normal mapping, what we need is “tangent”, which would be the tangent to the geometry. Is that correct? In that case, what exactly is “textTangent” and when does that get used?


Now that I think about it, I feel “textangent” could be the one to be used for normal mapping. That makes me wonder what the use of “tangent” could be.

For texture space, use the TEXTANGENT semanic. This is the typical use-case for “tangent space” normal maps.

For geometric space, use the TANGENT semantic. E.g object or world space normal maps.

Same distinction for binormal usages.