Jaime Vives Piqueres <jai### [at] ignoranciaorg> wrote:

> > Second thought: 4 points are one to much. Better use only 3 in a
> > equiliteral traingle at the borders of the drops. Then the plane
> > between this points on the blade is well defined (4 points may not
> > result in a plane) and the slopes can be calculated.
>
>    I was going to go for the 4 points approach, until you made this
> useful suggestion... thanks! For the slope, as clipcka said, the normal
> returned by the first trace() is enough to reorient the drop (and I was
> already using it, even if it's not very noticeable because the drops are
> too spherical).
>
>
> --
> Jaime Vives Piqueres
>
> La Persistencia de la Ignorancia
> http://www.ignorancia.org

Hi Jaime,
thanks for your response. The "more-then-2-points"-approach was not really meant
to determine the slope, but to ensure that the drop is completely on the blades,
the second issue I meant. You can determine the slopes from three vectors, but
of course you need only one. I was to entangled with a similar problem in
placing a mirror orthogonal to the viewpoint of the camera, where I used a
basis-transformation of two vectors with Shear_Trans() from the
transform-library to accomplish the correct rotation. The result is a WIP, which
is stalled for the moment, but may be you recognize the real author of this
scene...
Thank you for this! The trees are from arbaro.

Regards,
Michael

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