"Nekar Xenos" <go_### [at] yahoocom> wrote:
> We've all been thinking along the lines of doing it with a statement similar
> to media which is very complex. How about something simpler, like
> fade_colour? If the ior gets denser at a specific rate like fade_colour
> does, will this not make it more feasable to do?
>
>
> --
> -Nekar Xenos-
> ----------------------------------------
> "The truth is out there..."

The effect of a changing ior is not so much affected by the rate of change
of its value, but its change relative to the direction of travel of the
light ray.  In order for it to affect the direction, it needs to interact
with a change in iro along a surface not perpendicular to its line of
travel. So this would require, not only discrete sampling to determine the
ior along the light path, but also some sort of adaptive sampling to
determine an effective angle of incidence for the change in ior.  This
would not be entrely impossible, however, it would significantly increase
the calculations and overead involved and probably not give significantly
noticeable results versus what could be faked much more easily.

-tgq

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