3D linear filtering


Since my graphic card do not support 16 floating point linear filtering I decided to do it manually in a fragment shader.
I need to it for cube mapping.
Whereas it is trivial for 2D texture mapping I can’t find how I can do it for a 3D texture such as a cube map.

Is there someone who know how to do it or can give me some link about the subject?

Thanks a lot.

A cubemap is not a 3d texture, but is more like several 6 2d textures stitched together.
So the difficulties lies at the borders (and corners) between 2 (3) adjacent textures.
You may want to try first without bothering with these special cases.
Then tackle them checking the cubemap texture coords values.

Have a look here, there is a nice pdf presentation at the bottom here :

Thank you for your answer ZbuffeR,

Yes you are right, a cube map is not a 3D texture.
I am looking at the presentation and will see what I can do starting with it.