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Date: Thu, 9 Jul 2015 21:51:45 +0000
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Subject: Re: [geda-user] What is the hardest part in a PCB layout program?
From: "Evan Foss (evanfoss AT gmail DOT com) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
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The hardest part for me to understand when I look at the code is where
the geometry is processed vs where it is rendered.

OT: Is DRC checking done via the rendering engine or is there a
separate geometry engine that does this and verifies when traces and
etc are connected?

On 7/9/15, Stefan Salewski <mail AT ssalewski DOT de> wrote:
> I have to admit that I do not know much about internals of a PCB layout
> program. About 7 years ago I had a short look into the PCB code -- I
> think I was very positive surprised that code size was not too big, but
> of course I did not understand much.
>
> For a long time it was my impression that gerber export is very hard.
> But about one year ago I had a short discussion with someone working on
> some gerber stuff, and he said that for polygons, circular arcs and
> straight  lines gerber export is not that difficult. (I think he was
> talking about constructing arbitrary curves in KiCad by line segments.
> Can not really remember.) I think long time ago I read something about
> polygon slicer on this list -- can not find it currently with google. I
> had a look into wikipedia about gerber274X recently. My impression was
> that we had positive and negative shapes for polygons, arcs and line
> segments, which we can draw in arbitrary order. So my current impression
> is that gerber export maybe is not that hard. Maybe it was with old
> gerber274D ?
>
> Next difficult point is of course real time DRC, but that is basically
> geometric intersection check. For elliptical arcs segments it may be
> difficult I guess?
>
> And no, I do not plan one more layout tool currently...
> But while so many smart people are still on this list, it may be a good
> time to ask.
>
>


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