Josh English wrote:

> Normally you wouldn't need it, but POV-Ray describes a plane a bit
> differently and normal geometry would. In POV-Ray, D is the minimum
> distance from the origin to the plane. It is envsioned by going D units
> along the normal vector of the plane <A,B,C> and putting the plane there
> 
> In normal mathematical circumstance, D is not the mininum distance from
> the origin to the plane, it has a different meaning.
> For instance, mathematically, if you have a plane with normal vector
> <1,1,2> and it goes through point <2,1,3>, it satisfies the equation 1*2 +
> 1*1 + 2*3 = D, so D= 9.
> In POV-Ray, the same plane would have the same normal vector, but the
> disatance from the plane is less than 9.

Thanks both!
Where I need this information for, is a little program I'm writing, 
which does some calculations at points/planes. I want to calculate the 
distance of a point to a plain, with : 
abs(A*x+B*y+C*z-D)/sqrt(sqr(A)+sqr(B)+sqr(C)). I use that distance for 
some things and want the result being displayed by povray, but when 
povray uses another equation, the graphic would be false. How do I have 
to calculate the distance in my program, so that my calculations are 
correct with what povray displays?

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