kicad-developers team mailing list archive

[hauptmech <hauptmech@xxxxxxxxx>]

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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