dan wrote:
> 
> Explanation:  to generate realistic range images I need to create a Z based
> pigment using the 'gradient' pigment modifier.
> 
> Problem:   'gradient' wraps from 0 to 1 continuously based upon a modulo
> operation on Z, i.e. 'gradient' = fmod(z,1.0) where fmod = "floating point
> remainder" in VC6++   (see pattern.c, void gradient for more details)
> 
> Question:   how do I force or modify gradient z so that it is valid only
> from   0<Z<1 and gradient z = 0 otherwise?  If we can answer this question,
> then creating random dot stereograms and producing other such range imagery
> will become faster and more realistic using povray.  My only alternative at
> this point is to clip the scene, which causes a 10X increase in compute
> time.
> 
> #declare DepthMapTexture = texture {
>   pigment {
>       gradient z        // this little fellow keeps wrapping around with
> increased z, i want to make him
>       color_map {   // stop wrapping and return 0 when z > 1 and z < 0.
>         [0.0 color Black]
>         [1.0 color Red] }
>       scale 40
>   }
>   finish{ambient 1.0 diffuse 0.0}
> }
> 
> Many Thanks! dan

Does 'planar' do what you want?

PoD

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