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

[John Doty <jpd@xxxxxxxxx>]

On Sep 13, 2010, at 2:27 PM, DJ Delorie wrote:

> 
>> Now, the question becomes "which is more fundamental?".  I think
>> it's geometry.
> 
> A hole is the same geometry regardless of what level of the heirarchy
> it's placed at.  So let me rephrase: Why have seven geometric holes,
> one for each layer, when we can have one geometric hole applied to the
> whole composite?

I think that an object that spans more than one layer cannot sensibly be considered primitive in a layer-centric description of geometry.

My notion is that you need a general mechanism to align objects between layers. There are many cases where objects, primitive or composite, homogeneous or heterogeneous, require alignment. Having such a mechanism, you should then use it universally. If you bypass general general mechanisms for special cases, you risk creating a mess where general automation procedures fail in those special cases. Certainly you create a situation where the creator of automation needs to understand the consequences of all of the special case representations of objects.

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




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