[metapost] surfaces

[L. Nobre G.]

On 12/05/06, luis eduardo osorio <mat.eduardo at gmail.com> wrote:
> hi metapost friends, i have a big question (and problem to me), how i can
> draw t he intersection of surfaces in metapost code, for example i want draw
> the intersection between a parabolid and a cylinder. I reed somethig about
> featpost and mp 3D but i dont get good results. Well a hope that you can
> help me.

Hi,

Well, it is very easy to draw once you know what it is...
Since the intersection of those to surfaces my be zero, one or two
lines, the problem of drawing them reduces to finding a good
parametrization. That is not something that "software" can do (without
help). Additionally, if you are already thinking of the "goodie-box"
most graphics pakages usually offer, like hidden-line removal, I
repeat the words of Laurence Finston: it "comes out in the wash".

Anyhow, there is one very simple case, if both surfaces are surfaces
of revolution, their axis are parallel and the cylinder is infinite in
length, the intersection is one closed line and the parameter is the
angle around de cylinder's axis (you have done this, right?).

So, please tell us what do you mean by "good results".
-- 
L. Nobre G. - matagalatlante.org
--
"A física conhece a força fraca, a queda dos graves e o chumbo."
--
"Se soubesses o que custa ensinar, preferias aprender."