"PM 2Ring" <nomail@nomail> wrote:
> "Anthony D. Baye" <Sha### [at] spamnomorehotmailcom> wrote:
> > I'm working on a small experiment with 3d color-space, and it seems to be
> > working perfectly, it renders beautifully, but when it saves, the png files have
> > a truncated color table.  It's quite distressing.
> >
> > I've had no obvious trouble with other renders.
> >
> > Also, my jpeg output seems to be broken, and the render results are completely
> > different in windows 7.
>
> POV can read jpeg for image maps, but it doesn't use jpeg as an output format,
> due to the lossy compression.
>
> > I ran the same scene under both Windows and Linux using the same settings each
> > time +a0.3 +FN24 +W800 +H600
> >
>
> The +FN24 should be +FN8 or just +FN for a 24 bit PNG; the number refers to the
> bits per colour.
>
> See http://www.povray.org/documentation/view/3.6.1/219/
>
> > #declare r = function(x,y,z,rho) { rho*cos(atan(y/x))*sin(acos(z/sqrt(x*x +
> > y*y))) }
> > #declare g = function(x,y,z,rho) { rho*sin(atan(y/x))*sin(acos(z/sqrt(x*x +
> > y*y))) }
> > #declare b = function(x,y,z,rho) { rho*cos(acos(z/sqrt(x*x + y*y))) }
>
> I'm curious as to why you're using trig functions here. An algebraic approach
> using basic trig identities will speed things up enormously. See the Mandelbulb
> C code I posted recently in the "Accidental Isosurface" thread, which shows how
> to do the same functions as you require, but with no trig functions.

I could possibly simplify my approach, but it was a quick and dirty experiment;
besides, speed isn't the issue.  The issue is color loss under Fedora, which
could, possibly, be explained by having the wrong image libraries: except that
it happens with all formats.
The other issue is a discrepancy between what is rendered in windows, (3.7.0
beta 34) and what is rendered on other systems using the same release.

For the record, the image in p.b.i was rendered in Ubuntu 9.10 using +fn32.
Whether it's a valid usage of the argument or not, the number had no effect.

A.D.B.

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