hi,

Cousin Ricky <ric### [at] yahoocom> wrote:
> I have a couple of suggestions.  If you know the surface radius of each
> component, you can create a union of spheres, and take the center of the
> union.  Function RE_fn_Blob_surface_radius() in roundedge.inc can
> calculate the surface radii.
>   <https://github.com/CousinRicky/POV-RoundEdge>

yes, I can specify the radii, so, excellent, thanks, will check out the code.


> Alternatively, you can go brute force with trace() or inside(), and take
> the center of all the successful hits.  inside() would take longer than
> trace(), due to being volumetric, but it would allow you to compute a
> rough center of gravity, rather than just computing the center of the
> extents.

ah, there's the rub.  what I want, ideally, is to find the one point in a blob
which, when placed at origin, would allow me to rotate "the hell out of it" :-).
 unfortunately my maths/knowledge is .. abysmal, I do not (even) know whether
that specific point is the centre of the extents (what I meant by geometric
centre) or the centre of gravity.


regards, jr.

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