A fair question is, does it matter? It depends. For some looks you're better off with a dielectric film (it renders faster). But when it does matter, there's no denying the absorption is required for the right look.

Example: copper with a layer of CuO, where the layer doesn't have absorption. Compare with the image in the first post of this thread (repeated here), where realistic absorption is added.

Now I need a real Dev to fix my baby C++ code😅
3/3
#blender3d #b3d #thinfilminterference