"Rarius" <rar### [at] rariuscouk> wrote:
> I just can't get my head around this problem...
>
> I am trying to render a high resolution image of Saturn's rings. I can't use
> colour maps for this as they won't have the resolution required (I believe
> colour_maps are limited in the number of elements you can have!)
>

It is true that maps are limited to 255 entries, but if you use a pigment map
with nested color_maps, the pigment_map may have 255 entries, each with a
color_map containing its own 255 entries.

> I have written a group of float functions that produce the red, green, blue,
> transparency and several various albedo values. I also have a function that
> varies between 0 and 1 across the ring plane... OK so far.
>
> My problem is that I cannot seem to combine these to produce a pigment.
>
> The following code fails with a "numeric expression expected" error...
> disc
> {
>     0, z, OuterEdge, InnerEdge
>     pigment
>     {
>         rgbt<fRingRed(x,y,z), fRingGreen(x,y,z), fRingBlue(x,y,z),
> fRingTrans(x,y,z)>
>     }
> }
>
> It appears you can't put functions into a rgbt<>.

I am assuming those are pigment functions, which do not return a single value -
they return a color 3vector.  Assuming that they are returning a grayscale
value, you can change that to:

pigment
{
color rgbt <fRingRed(x,y,z).red,
            fRingGreen(x,y,z).red,
            fRingBlue(x,y,z).red,
            fRingTrans(x,y,z).red>
}

Note that while I am extracting what would be the red component, this doesn't
have anything to do with the color produced by the pigment.  I am just pulling
the first float out of the 3 vector.

    HTH
  -Reactor

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