Nathan Kopp <Nat### [at] Koppcom> wrote in message
news:3740DC55.26A3866B@Kopp.com...
> Macros work via text substitution.  Rmm is not really a function returning
> a number.


    POVRay documentation says differently, see: "Returning a value from a
macro" or some such. I'm too groggy to think about his macro but it can be
made to act like a value in the pigment.


> Right now, this:
>     pigment {rgb <0.50,0.10,0.08>*Rmm(Min,Max,Stream)}
>
> becomes:
>     pigment {rgb <0.50,0.10,0.08>*Max+((Min-Max)*rand(Stream))}
>
> So, you need to put parentheses in the macro.  Change it to look like
> this:
>
> #macro Rmm(Min,Max,Stream)
>    (Max+((Min-Max)*rand(Stream)))
> #end file://macro
>
>
> -Nathan
>
> ingo wrote:
> >
> > While making some pieces of wood with different colours, using random, I
ran
> > into a problem.
> > Run the scene below.
> > The first number from the random stream ia always 0.118 .
> > Now comment out "#declare XX = ....." , "#debug concat(....." and in the
the
> > first pigment replace XX by "Rmm(0.1,0.5,Sd)".
> > Run the scene again.
> >
> > Why are the colours different?
> >
> > ingo
> >
> > --
> > Met dank aan de muze met het glazen oog.
> >
> > #version 3.1; global_settings {assumed_gamma 1.0}
> > light_source {<500, 500,-500> rgb 1}
> > camera {location<0, 1.6, -5.0> look_at<0,0,0>}
> >
> > #declare Sd=seed(7)
> >
> > #macro Rmm(Min,Max,Stream)
> >    Max+((Min-Max)*rand(Stream))
> > #end file://macro
> >
> > #declare XX= Rmm(0.1,0.5,Sd)
> > #debug concat("\n XX= ",str(XX,3,3))
> >
> > #declare Wood= texture {
> >    pigment {rgb <0.50,0.10,0.08>*XX}
> > }
> > texture {
> >    pigment {
> >       wood
> >       scale 0.05
> >       color_map {
> >          [0,rgbf <0.5,0.4,0.4,0.2>*0.5]
> >          [1,rgbf <0.5,0.4,0.4,0.7>*0.5]
> >       }
> >    }
> > }
> > box {-1,1 texture {Wood}}

Post a reply to this message