# another yucky geometry question

TJ Frame tjframe at gmail.com
Mon Sep 26 20:53:36 CDT 2005

```Thanks so much Jim, but alas, as this screenshot shows neither axis will
ever be parallel since this is a 2D perspectiev drawing utility. This second
image of the link is a screenshot shows a typical VP setup that might exist
and all the variations of ellipses that might result...
http://www.tjframe.com/EllipseExample.htm
But as I alluded to earlier, Perhaps this would be beyond the scope of
something I could implement. I know that 3D do ellipses every day, all day
long, so I had assumed it would be a straightfoward task. But I guess they
use matrix calculations to generate the points of the object rotated and
stuff. Perhaps I would need to have a 3D underpinning for the ellipse stuff
to work..
For now I'll put that feature on hold.
Thanks again guys,
- TJ

On 9/26/05, Jim Hurley <jhurley at infostations.com> wrote:
>
> >
> >Message: 15
> >Date: Mon, 26 Sep 2005 13:47:41 -0700
> >From: TJ Frame <tjframe at gmail.com>
> >Subject: Re: another yucky geometry question
> >To: How to use Revolution <use-revolution at lists.runrev.com>
> >Message-ID: <7348a9e805092613477d210455 at mail.gmail.com>
> >Content-Type: text/plain; charset=ISO-8859-1
> >
> >Thanks for your help guys, I didn't realize it was so tough a problem to
> >solve :(
> > perhaps I'll have to rethink the way I'd like to implement them.
>
> TJ,
>
> I think I see what you are looking for: An ellipse which is tangent
> to the two radial lines and the two end lines. confined between the
> two end lines--also tangent to the ellipse.
>
> The stack below calculates the point on the ellipse where the tangent
> to the ellipse is parallel to the radial lines and then puts the
> ellipse there. I have confined myself to the case where the major
> axis of the ellipse is parallel to the x axis. It gets grubby
> otherwise. This was fun. I hate grubby.
>
> In the message box:
>
> go stack url "http://home.infostations.net/jhurley/EllipseInAbox.rev"
>
> Hope this helps.
>
> Jim
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```