kicad-developers team mailing list archive

[hauptmech <hauptmech@xxxxxxxxx>]

The tokens for circles are fine.

I suspect it will come up about as often as it has (so once in 5 years?).

Perhaps you could a couple lines of documentation for fp_arc in the file 
formats pdf so the next person that encounters this has a chance to 
recognize the error? It would have saved me a bit of time and 
frustration had some (any) documentation been there.




On 28/06/17 03:32, Wayne Stambaugh wrote:
> The tokens in the file format match the member names of the DRAWSEGMENT
> object so I see how this could be confusing for arcs and circles.
> Changing the "start" token to "center" is not a can of worms that I want
> to open.
>
> On 6/27/2017 8:45 AM, hauptmech wrote:
> > Just to clarify, I'm talking about the file format not the internal
> > implementation.
> >
> > The file_formats documentation has the old format using 'center' and
> > 'start' for circles and 'start' and 'end' for arcs (which go from a
> > start point to and end point as the terminology suggests). All good and
> > well.
> >
> > fp_circle has 'center' and 'end'. Makes sense.
> > fp_arc is defined by a center point and a start point. Different than an
> > arc defined by a start point and an end point.
> >
> > Arcs are a bit tricky since there are so many representations (choose 3
> > of center, start, end, and angle). Mislabeling the file format doesn't
> > help things.
> >
> > I spent quite a while pouring over my arc generation math before
> > checking to see if kicad was doing something funny with it's start, end,
> > angle fp_arcs.  Imagine my surprise to find out there was no such thing
> > even though the s-expressions said there was and the old file format
> > confirmed that that was the way kicad did things.
> >
> > I hope you can see why I thought this is an error.
> >
> >
> >
> > On 28/06/17 00:07, Wayne Stambaugh wrote:
> > > It's not an error.  Arcs are part of the DRAWSEGMENT object which
> > > encapsulates line segments, arcs, etc.  The start coordinate (m_start
> > > member) is the center point for arcs and circles.  It is documented as
> > > such in the KiCad source.
> > >
> > >       wxPoint     m_Start;  ///< Line start point or Circle and Arc center
> > >
> > >
> > > On 6/26/2017 8:19 PM, hauptmech wrote:
> > > > In the module s-expressions, what is the rationale for having arc center
> > > > labeled 'start' and having the arc starting point labeled 'end'?
> > > >
> > > > This bit me as I was writing an Allegro footprint extractor to kicad and
> > > > got confused why my start,end,angle arcs were not displaying correctly.
> > > >
> > > > Assuming it's an error, is there a way to fix the file format or is this
> > > > a permanent thing?
> > > >
> > > >
> > > >
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