Re: [PATCH] New pm3d corners2color function

[sfeam (E. Merritt) <eam...@gm...>]

On Sunday, 07 October 2012, Petr Mikulik wrote:
>Ethan Merritt wrote >
> > There is an option "set pm3d interpolate <xdelta>,<ydelta>" that
> > produces smoother coloring subdividing each quadrangle into smaller
> > quadrangles with individually calculated color values.  But these
> > color values are always assign by linear interpolation.
> >
> > For color schemes c1/c2/c3/c4/mean this comes out equivalent to the
> > same overall coloring applied to a finer grid of x,y values.  The
> > finer the interpolation, the closer it comes to a true linear color
> > gradient.
> >
> > However, for color schemes using the harmonic or geometric mean,
> > the finer grid still results in a linear color gradient rather than
> > the requested geometric or harmonic color variation.  Shouldn't the
> > interpolation in these cases be some non-linear function?
> > What function would that be?
> 
> Coordinates x, y can be interpolated linearly, but the colour coords can 
> follow arithmentic, geometric or harmonic mean.

Sure, but what are the corresponding interpolation functions?
If the c1/c2/c3/c4 quadrangle is to be colored using a harmonic mean,
and interpolation 3,3 splits adds four new vertices in the interior,
what is the proper interpolated color at those new vertices?

Clement Law <the...@gm...> wrote>
> I've written up another pm3d corners2color function. It works just as
> the others, i.e.,
>   set pm3d corners2color rms
> rms4 takes the root mean square[1] of the four corners

OK.
Do you see what I'm asking about how to handle interpolation
for these non-linear coloring schemes?

	Ethan