"Warp" <war### [at] tagpovrayorg> schreef in bericht 
news:457fc925@news.povray.org...
> Thomas de Groot <t.d### [at] internldotnet> wrote:
>>     #if (Norm.x != 0 | Norm.y != 0 | Norm.z != 0)
>
>  Btw, another way of testing that is:
>
>  #if(vlength(Norm) > 0)

Ah, yes! that's neat!

>
>>       #if ((vdot(Norm, y)>0.5) & (Pos.y < 5.5))
>
>  Does trace() always return a normalized vector?
>

Yes, if you define also the fourth trace parameter (a vector), Norm in this 
case (see documentation 3.2.1.4.5). This works fine as far as I can tell. To 
tell the truth, I used this after an example from somebody else :-)  So, 
things are transmitted on. However, there might be an even better way to do 
this, but I have not investigated that far as this worked for me.

Thomas

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