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Re: gEDA-user: Adding inner polygons to a plane



On Thu, 2011-05-12 at 14:05 +0100, Robert Spanton wrote:
> On Wed, 2011-05-11 at 19:19 +0100, Peter Clifton wrote:
> > Perhaps it would be possible to support a flag on the "smaller",
> > clippiING polygon which makes it "bully" other polygons away from it,
> 
> EAGLE does this by allowing the user to assign a numeric priority to a
> polygon.  Polygons with higher priority get to "bully".
> 
> > but again - it is not clear what to do in the case where two polygons
> > with this flag touch each other. (Just short with each other I guess).
> 
> I suspect that shorting the polygons together would be the exact
> opposite of what the user wanted most of the time.

They would soon learn to stop drawing overlapping polygons though ;)

> Perhaps it should create a DRC violation, with neither of the polygons
> rendering until the user has fixed the problem (with some kind of visual
> indicator to show that this is happening!).  It seems to me that this
> would result in the behaviour of least surprise and fewer broken PCBs.

Shorting is not going to break anyone's PCB - its just one of many ways
we "could" operate, and would influence how the user draws their
geometry.

Perhaps a simple Z-Order (perhaps file location based) would suffice,
and we could add "bring to front" / "send to back" commands somewhere.

Top-most polygons clip and bully lower polygons etc..

I can't recall exactly why, but I recall being partly opposed to
Z-ordering within a single layer before. It might be because it would
tend to produce big diffs in the PCB file for Z-ordering changes.

Assigning numbers is another way to do it, but you do have to ensure
numbers aren't duplicated, and ideally - don't have gaps.. Hmm..

-- 
Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,
Cambridge
CB3 0FA

Tel: +44 (0)7729 980173 - (No signal in the lab!)
Tel: +44 (0)1223 748328 - (Shared lab phone, ask for me)

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