Re: gEDA-user: An idea: rework design support...

[Stephan Boettcher <boettcher@xxxxxxxxxxxxxxxxxx>]

Peter Clifton <pcjc2@xxxxxxxxx> writes:

> FWIW, I'd love to see PCB's enforce one "layer" per "layer" of the
> board, tagging objects if necessary to implement similar functionality
> to what we currently use "layers" and "layer groups" for.

One layer per physical layer would imply that element pins (pads) are
tagged shapes in this single layer too?

And negative shapes as well?  So each object (shape) on the layer needs
a stacking order tag (implying sublayers), or shall each negative shape
take precedence over positive shapes?

> Mechanical drawing overlays could still sensibly be called "layers",
> even if they are quite distinct from the physical representation of the
> PCB board.

I do not have a problem with the idea of single layer per physical
layer, as long as the end result is no more than a separation of the
plane in two subsets, all layers can be manipulated othogonally in the
same way (at least with a text editor), and there are not too many
assumtions about the semantics of the resulting layers.  The tags on the
objects that define the layers have several distinct purposes:

 - how does this object affect the plane (positive, negative, positive
   with clearance, stacking order, ...)

 - where did this object come from (routing, element pin, ...)

 - how may this object be modified (locked, grouped, ...)

 - verification (design rules, ...)

 - connectivity (vias, antenna, ...)

 - ...

 - user attributes

Some of these tags exist today, some are requested features, some depend
on what gets picked up from the long discussion we had a few months
back.

-- 
Stephan


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