Cousin Ricky <ric### [at] yahoocom> wrote:

> How does one put a hue gradient on a light source?  Are you thinking
> about a filter in front of the light source?

Put a hue gradient on an object and give it an emission 1 finish?
Use projected_through?

  And how would you convert
> ROYGBIV into an interference pattern?

Look at the rainbow pages.  They have interference patterns for different
colors.  Then they sum them up.  Write a macro that creates the functions for
the wavelengths and sums them up.  Have the number of discrete wavelengths that
you want to use in the visible spectrum be the argument for the macro.

Something with a Fourier transform?

- or -

I don't think we would.  I think we'd diagram out what would happen if the
interference pattern was the originating mechanism of the result - but then see
if there's just some overall function that describes the HSV result.

Or just fake the hell out of it with something that for all intents and purposes
looks good enough.

My Fresnel diffraction pattern was rendered with a simple equation describing
the end result.  I didn't model the interference in any way whatsoever.

I think the key here is to not get all tangled up in trying to work _through_
all of the physically-based processes - but rather summarize the overall result.
Like writing out the big intermediate equation - and then canceling out a bunch
of terms.  Physicists apparently do intermediate calculations with imaginary
numbers and negative temperatures - but that's only the procedural path to the
answer.

I posted a lot of stuff that doesn't try to calculate an infinite number of
wavelengths.  Let those be the guide.

How do we calculate integrals?  Those can be considered the sum of an infinite
number of thin strips underneath the curve - but we don't actually process those
infinite number of strips, do we?  We just "do the math", and the result pops
out the end.

So we just find a way to "do the math" and get something that works.

- BW

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