- Split the function so that the 3-components loop is more apparent.
- Factored out the parts of the computation that don't depend on the
index of refraction, so they're only computed once.
- Moved the lod-from-roughness computation out of the loop as well.
It does depend on the IOR, but so little that it's not worth it.
The most important result of this change is that the code is now in
good shape if we wanted to change the implementation of dispersion for
these cases (for e.g.) :
- do the computation in the XYZ space
- use more than 3 wavelengths samples
- or use a stochastic approach, trading banding for noise
RDIFF_BRANCH=ma/better-dispersion
Mathias Agopian
5661365248