kicad-developers team mailing list archive

[Avishay Orpaz <avishorp@xxxxxxxxx>]

The problem is that the definition of an arc in the legacy file format is
ambiguous. A center point and two additional points (or angles) define two
possible arcs - one smaller than 180 degrees and one larger (or two equal,
180 degree arcs). In order to distinguish between the two, additional
constraint is required. If I understand correctly, the constraint here is
that the arc is strictly smaller than 180 degrees. In the new file format,
a midpoint is specified, solving this ambiguity.

Avishay

‫בתאריך יום ג׳, 12 בנוב׳ 2019 ב-23:28 מאת ‪Evan Shultz‬‏ <‪
evan.shultz@xxxxxxxxx‬‏>:‬

> I've also found
> https://www.compuphase.com/electronics/LibraryFileFormats.pdf to be
> useful.
>
> On Mon, Nov 11, 2019 at 4:14 AM Wayne Stambaugh <stambaughw@xxxxxxxxx>
> wrote:
>
>> Take a look at the legacy footprint library file format documentation[1]
>> for help.  You really should be supporting the new s-expression file
>> format.  The legacy file format is deprecated and is read only.
>>
>> [1]:
>> http://bazaar.launchpad.net/~stambaughw/kicad/doc-read-only/download/head:/1115%4016bec504-3128-0410-b3e8-8e38c2123bca:trunk%252Fkicad-doc%252Fdoc%252Fhelp%252Ffile_formats%252Ffile_formats.pdf/file_formats.pdf
>>
>> On 11/11/2019 4:42 AM, Avishay Orpaz wrote:
>> > I'm writing a program the reads schematic library symbols, and I'm
>> > having hard time understanding how arcs are drawn.
>> > Taking, for example, the Antenna_Shield symbol from device.lib. This
>> > symbol contains two arcs:
>> >
>> > A -1 -73 32 -882 1242 0 1 0 N 0 -105 -20 -45
>> > A 1 -73 32 -918 558 0 1 0 N 0 -105 20 -45
>> >
>> > Both arcs start at approximately the same angle (-90 = 270 degrees) and
>> > end at two different angles - the first at 124 degrees, the second at 56
>> > degrees. When the symbol is drawn, the first arc is drone clockwise
>> > while the latter is drawn anti-clockwise. So, how is it possible to
>> > determine the direction of the arc?
>> >
>> > Avishay.
>> >
>> >
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