kicad-developers team mailing list archive

[Wayne Stambaugh <stambaughw@xxxxxxxxx>]

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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> 
> 
> 
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