[cad-linux-dev] Re: thing'd-foo
- From: Bruno Postle <bruno@xxxxxxxxxx>
- To: CAD linux development <cad-linux-dev@xxxxxxxxxxxxx>
- Date: Mon, 23 May 2005 11:17:59 +0100
On Sat 21-May-2005 at 12:09 -0700, Eric Wilhelm wrote:
>
> But wait. Arcs are still circles, they just have those 'angles'
> thingies.
..but surely circles are just ellipses with eccentricity = 0 and
ellipses are just a class of conic sections - You could devise a
data storage class that did arcs, circles, elliptical arcs,
parabolas etc... all at once.
However, sometimes it is really useful to think of a circle as a
point with a radius or as three points or as two points and a bulge.
If you are doing parametrics then that is exactly the kind of
variation you need. For example, the centre-point of a circle might
need to be a reference to a node in a polyline and the radius might
be equal to the text content of a text entity - Difficult to layer
this stuff onto a conic-section super class.
--
Bruno
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