this seems more complicated to me, but I never studied optics, I just tutor high
school algebra and
geometry. I suppose if you could find the proper intersection of plane and cone and
find a way to
rotate it appropriately, it would work. I'm still stuck on finding a tangent to the
ellipse at any
given point on the edge of the ellipse.
I also haven't heard from Andrew in this thread, so I wonder if he has a solution or
not

Josh English

Steve wrote:

> I don't have the solutions, but I have an impression that the trig approach is a bit
contrived.
>
> Perhaps you should be looking for a more generalized method.
>
> The sphere is is a conic cross section (angle 90) formed by revolution. It's
perfectly described
> by the math for conics. Size is derived by locating the cross section along the
vertical axis.
> Using this seems fairly simple, plus it would also solve the problem of rolling
ellipsoids along
> the floor. Instead of scaling, use the location of the cross section to derive the
size.
>
> A generalized solution of this type would further yield parabolic and hyperbolic
movements.
>
> Just an idea from my old optics days.
>
> steve

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