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From: geda AT psjt DOT org (Stephan =?utf-8?Q?B=C3=B6ttcher?=)
To: "Nicklas Karlsson \(nicklas.karlsson17\@gmail.com\) \[via geda-user\@delorie.com\]" <geda-user AT delorie DOT com>
Subject: Re: [geda-user] The nature of gEDA users
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Date: Wed, 27 Jan 2016 09:52:47 +0100
In-Reply-To: <20160127091746.1c7a976c2752f913921688ac@gmail.com> (Nicklas
	Karlsson's message of "Wed, 27 Jan 2016 09:17:46 +0100")
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"Nicklas Karlsson (nicklas DOT karlsson17 AT gmail DOT com) [via
geda-user AT delorie DOT com]" <geda-user AT delorie DOT com> writes:

>> >> > But the first steps should not be "implement b/b vias" or "allow more
>> >> > than one pair of outer layers".  It should be something like "express
>> >> > Elements and Vias as subclasses of generic containers that can include
>> >> > anything".
>> >> 
>> >> +1
>> >> 
>> >> John Doty              Noqsi Aerospace, Ltd.
>> >> http://www.noqsi.com/
>> >> jpd AT noqsi DOT com
>> >
>> > I am probably on same track. A via or hole is: drilled cut out thru
>> > all layers with plating
>> 
>> No.  A via is a collection of circles, negative circles, thermals on
>> conductive layers, and a circle on a layer connecting the copper circles.
>> 
>> The technology and DRC ruleset knows that the circles shall be drilled
>> at slightly larger diameter and filled with plating, and check the
>> copper circles accordingly.  But that is several orders up in the
>> abstractions stack.
>> 
>> -- 
>> Stephan
>
> I got slightly wrong and would only add the circle connecting the
> copper circles really is a cut out or negative circle as you call it.

No.  The circle connecting the copper circles is on a different layer,
and is not negative, i.e., not a cutout.  The gerber export of a copper
layer has no hole where the drill hits.

It is the overlap of an object on the copper layer and an object on the
via layer that provides the connection.

"copper" and "via" are just names for "conductive" and "inter-layer
connection"

> I assume the following objects are equal and give the same result:
> drilled hole, negative object, cut out.
>
> To drill a hole thru only some of the layers I consider a little bit
> more involved. If I got objects wrong is less important. Do you think
> it would be good with possibility to draw on any layer inside element,
> pin, via, pad for those special cases that are a little bit different?

Any object shall be allowed everywhere.  But the GUI does not need to
support that initially, if that is difficult, orclutters the user
experience.

I had no problem to draw Arcs that are not 90° in the past, using Emacs
or Gnumeric.  Nor do I see a problem to move Element pads from the
nominal component layer to a flex surface layer with a text editor.  The
data structures must support that.

The data structures must efficiently represent the geometry and the
connectivity.  Everything else can be defined in tools that operate on
the data structures, driven by attributes.

-- 
Stephan