kicad-developers team mailing list archive

[Jeff Young <jeff@xxxxxxxxx>]

+1 to start, end and ....
+0 to whatever ... is.

> On 10 Jul 2019, at 18:37, Larry Doolittle <ldoolitt@xxxxxxxxxxxxxxx> wrote:
> 
> Jon -
> 
> On Wed, Jul 10, 2019 at 01:29:11PM -0400, Jon Evans wrote:
>> I am curious why start-midpoint-end is better than start-center-end, though.
>> I think the latter is used more often in mcad tools, although I could be
>> wrong.
> 
> start-center-end is mathematically over-constrained, so it sounds
> worth avoiding.
> 
> start-midpoint-end encodes a useless -- but not over-constrining --
> degree of freedom, in the position along the arc of the "midpoint".
> 
> The mathematically correct number of parameters is five, and Seth makes
> a good case that four of them should be the start and end coordinates.
> One non-pathological definition of the fifth parameter is curvature,
> in units of inverse-distance.  Zero is no curvature -- converts back to
> a straight line.  The sign of the curvature tells whether the arc bends
> left or right.  I _don't_ assert that this is any better in real life than
> start-midpoint-end.
> 
>  - Larry
> 
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