"Daniel Matthews" <lig### [at] bigpondnetau> wrote in message
news:128### [at] 3-enet...
>
> Thanks I will have a play with that. I gather that any detail that is cut
> to a certain depth exposes a darker part of the pigment, thus emulating
> dirt accumulation in all grooves of sufficient depth.

Yep, it's just a simple layered texture trick.

> The problem is that grime deposits are normal variance dependent.
> How can I have a texture in POV that is dependent on a calculation
> involving it's normal in relation to surrounding normal values?
>
> Must I use POVMan and a renderman style shader?

Since I'm almost positive official POV-Ray 3.1 has no ability to follow only
normals with patterns in any way that's probably a safe bet.  I just never
have used POVMan.  Although... MegaPOV does have a surface slope pigment
pattern, and also a post_process which can follow surface contours.  Has
trace() too.
BTW, I kind of lost track whether that bas relief remained as normals only
or were turned to CSG.  If only normals I'm uncertain if MegaPOV alone could
do anything then.
Anyone might know better than I do anyhow.

Bob H.

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