Warp <war### [at] tagpovrayorg> wrote...
>   Wouldn't it be faster to calculate the normal of a (pattern) function
using
> its derived versions (d/dx, d/dy and d/dz)? This way only three functions
> have to be calculated instead of four. If it's a 2D function only two
> functions has to be calculated. If it's a 1D function (like gradient),
only
> one function has to be calculated.
>   (Povray doesn't have to calculate the derived functions itself; they are
> of course hard-coded as the original functions themselves.)

This is already done for bumps, dents, waves, ripples, and wrinkles.  This
is actually why these functions act differently than other functions when
scaled in POV 3.1 (and that is the reason for the "normal bugfix" in
MegaPov).  Also, slope_map appears to be ignored when these normal types are
used, and I think that this is because it's not possible (or at least not
easy) to compute the gradient taking into account the slope_map.

-Nathan

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