Re: gEDA-user: next PCB release - 1.99za vs 4.0

[John Doty <jpd@xxxxxxxxx>]

On Sep 12, 2010, at 7:53 PM, DJ Delorie wrote:

> 
>> And I think the only way to do ... in a non-kludgy way
> 
> Yet another example of you automatically putting down any idea that
> isn't yours.  Please stop that.  Please consider the possibility that
> someone might come up with a better (or even equally good) idea than
> yours.  Constructive criticism is welcome.  Implied insults are not.
> 
>> is to treat the insulating planes as layers, each with its own
>> geometry.
> 
> So, you're saying drills and outlines should be stored on "insulator"
> drawing layers and the "conductor" drawing layers should only contain
> the actual conductor shapes?

Typically, the user will draw composite objects that occupy multiple geometric layers. The GUI will have a "library" of common composite objects. Users are not going to want to work directly with geometric primitives unless it's necessary. But when it *is* necessary, the underlying data representation must allow the user to make direct contact with primitive geometry.

> 
> That means a simple two-layer board is going to give the user three
> drawing layers, minimum, not including the [expected] silk/mask/paste.

That's geometry. In engineering, never fight the mathematics or the physics. Instead, use them.

> I suspect asking about that third layer will become a FAQ if we don't
> get the GUI right.

It's not so much the GUI, but the higher level description that matters. Users who don't bore down to the lowest levels need not see that detail. But if you don't have that solid low level foundation, you'll spend your life implementing kludges to get special behaviors.

> 
> It also means that the boundary for an inner conductor layer may be
> one of two possibilities - PCB would then need to know not just the
> stackup, but the manufacturing sequence - which insulator carries the
> conductor film before etching/printing.

In general it it needs that information. Consider a buried component: you need to know the stackup to know which insulating layer(s) host the cavity.

> 
> 
> _______________________________________________
> geda-user mailing list
> geda-user@xxxxxxxxxxxxxx
> http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
> 

John Doty              Noqsi Aerospace, Ltd.
http://www.noqsi.com/
jpd@xxxxxxxxx




_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user