Re: gEDA-user: PCB format wishlist

[Andrew Poelstra <asp11@xxxxxx>]

On Mon, Sep 06, 2010 at 11:24:58AM -0600, John Doty wrote:
> 
> Choosing the right level for the primitives is important. I wouldn't drop
> below a "planar stack of geometric shapes" here. But I wouldn't go higher
> for primitives either. One might very well wish to draw arbitrary shapes
> in silk, or one might require holes of arbitrary shape. I once worked with
> a board that had different numbers of layers in different places, and with
> different conductive materials for different traces (not designed with pcb!).
> A well-factored design should be able to express this kind of thing.
> 
> A format that would be equally at home specifying the layout of a printed
> circuit board, a VLSI chip, or a Mondrian painting would be a good target.
> I don't think we need to go as far as spherical circuits or Picasso ;-).
>

Sounds good. But I'm worried that by dropping down to basically a vector
drawing, we're going too far. However, given that any decent file format
will let us create PCB objects from geometric shapes, perhaps this is
an unjustified fear.

>
> ... 
>
> It's often necessary to align shapes on different layers: that's not a
> special property of vias. So, the machinery of composition of objects from
> more primitive objects needs to be able to control that. Then it would make
> sense to use that machinery to compose vias. The reason we can't have blind
> and buried vias is a consequence of the lack of such factored, orthogonal
> design in pcb at present.
> 

This is a very good point. I agree with it.


Andrew



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