Peter Popov wrote in message <3755fdc2.38371480@news.povray.org>...
>
>You are right.
>
>How about... if all falloff functions can have an optional axis
>specified? The values will then fall off in one direction, i.e. the
>equipotential surfaces will be planes as opposed to spheres. All we
>need is take a projection of the vector from the center of the
>"whatever we are modifying the falloff of" to the point in question
>and project it onto the axis (do a dot product with the normalised
>axis vector)?
>

Thet might do the trick on more-or-less planar surfaces. But when the
surface has steep curvature, I imagine you would see a strange pattern since
the amount of twirl is different at different heights. Hmm... The spiral
would start curving back towards the original position as the twirl falls
off... I think.

>
>Maybe. If the plane of twirling is the plane through the center of the
>twirl and perpendicular to the plane defined by the current camera ray
>and twirl center.
>

Reread the sentence and say it isn't confusing :) I believe I'm rephrasing
what you said, but here's how I imagine it. The twirl plane would be defined
by 3 points: camera location, warp center and current intersection point.
Twirl axis - the normal vector of this plane.
The question is, how would this behave in an animation?


Margus

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