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Date: Fri, 27 Jun 2014 13:27:07 +0200
From: Gabriel Paubert <paubert AT iram DOT es>
To: geda-user AT delorie DOT com
Subject: Re: [geda-user] pcb: Patch for arcs with different radii for x and y
 on screen
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On Thu, Jun 26, 2014 at 05:34:00PM +0100, Peter Clifton wrote:
> On Mon, 2014-06-23 at 10:44 +0200, Philipp Klostermann wrote:
> > Am 21.06.2014 14:30, schrieb Peter Clifton:
> 
> > Isn't this rather a general problem, not restricted to elliptical arcs?
> 
> Yes, but elliptical arcs are the only primitive we currently support in
> PCB that are not well supported by the common export formats we target /
> may wish to target.
> 
> The one thing to be aware of, if you use elliptical arcs in footprints,
> is that due to their parametrisation, such footprints cannot correctly
> be rotated by arbitrary angles.
> 
> A fix for that will probably (in the first instance), adding rotation as
> an explicit transformation to the footprint as a while - rather than as
> we currently do, applying the transformation to each individual entity
> within the footprint.

I agree completely, rotating the individual parts also leads to problem
of precision with repeated rotations. 

But if you are going to change the file format, there are other things
to introduce:
- blind and buried vias
- arbitrarily rotated text
- contours with arcs boundaries (I know you had a patch for this)
- correct square pads
- complex pads (look at an MC15XS3400 for fun) 

> 
> If elliptical arcs were useful enough, we might consider extending the
> representation in PCB to allow arbitrary rotation of that primitive as
> well.

The format should allow arbitrary rotation of any item.

	Gabriel