"Christoph Hormann" wrote:
> > * vtransform don't give access to the different parts of the
transformation
> > (which I named X, Y, Z and P), and thus the correct weighted average
cannot
> > easily be performed. If you insist that it can be done, please provide a
> > macro that takes a weighted average of any number of transforms.
>
> I don't see a reason why it's more difficult to do this in
> Pov SDL than in c code. Implementing your idea directly in
> Povray does require the same calculations.

Internally POV-Ray has access to the different parts of the transformation
matrix (X,Y,Z,P), while this can't be accessed directly from the SDL. An
average of transformations can only be taken if those parts are known.

But anyway, I've just remembered the ultimate argument why it can't be done
in SDL, at lest not for smooth meshes:

In order to transform a normal, one has to know the corresponding vertex.
However, in mesh2 each normal can be assigned to several vertices. Thus it
is impossible to transform the normals of mesh2 in the SDL.

> I do not say a function like you suggested is nonsense,
> but before writing a patch for that it would be useful
> to try it in Pov SDL and see how it works.

I guess it would be possible for a low-resolution non-smooth mesh, where
each vertex is assigned to one transformation only, not an average.

I'll do some experiments.

Rune
--
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