"lelama" <nomail@nomail> wrote:

> Hi Bald Eagle,
> Unfortunatly, the vertices of the triangles are not the top and bottom of the
> shperes. This is the tricky part.


Yes, yes - now that I got some sleep an coffee, I see that it should have been
obvious that it's the "belt/pulley problem" all over again.


> One coefficient has been discovered using a pair of spheres. Since there are
> three pairs of spheres that you can use, this finally gives completly the
> coefficients of the plane tangent to the three spheres.

I'm following you.  I had to play around with the equations of a plane when I
was working out all the details of the camera view frustum.

Still moving, so it may be a while before I'm able to take the time to read the
code and work out what's going on, but I can see the forest through the trees at
this stage.  ;)  Thanks for the clarification.

> > I've been meaning to code up some of the more basic "here's where two lines
> > intersect" type tools - but then some damned thing IRL always becomes higher
> > priority.  :(
>
> Many of these geometric tools (intersection of
> lines,planes,projections,coordinate changes...) have been implemented
> in Pycao ( my software to describe povray scenes with the python language). Feel
> free to use it or to look at the code if you prefer the povray sdl language.
> (This is a gpl license).

That sounds great  :)
Given that so many things need to be aligned and positioned with "geometric
accuracy" and done via math/SDL, these are tools that are fundamental to the
tasks required to build such objects and scenes.

Glad to see there are others interested in working it all out.

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