[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

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

On Wed, 2011-05-11 at 15:17 -0400, DJ Delorie wrote:
> One of the things I suggested for Peter's pours branch is to add
> another level of polygon-ness.
> To summarize, pours creates two layers of polygons - the layer the
> user creates, and the "cut up" polygons caused by traces, vias, etc.
> PCB's core sees the cut up polygons, not the user ones, so things like
> DRC and connectivity work properly.
> I suggested a layer of cut-lines between the user polys and the cut up
> pols, thus:
> Level 1: user-editable top-level polygons (whole polys)
> Level 2: user-editable "traces" which slice up polygons (sliced polys)

Level 2 is the missing layer, and yes - it would be really neat to have.
I once had an "anti-polygons" branch, this would be more like
"anti-tracks". In general, we probably ought to support "anti-anything".

> Level 3: PCB PolygonType objects further cut up by polygon clearances
>          etc (sliced & cleared polys) (i.e. what you see in the gerbers)
> Level 4: output of polygon dicer (sliced, cleared, and diced polygons)
>          (transient, used by exporters)

Dicer? How quaint ;)

GL doesn't use it, PS export doesn't use it. In fact, only gerbv and PNG
really need it I think.

Actually, I suppose being fair - the GL render "could" use the dicer. It
could also use its Bentley-Ottman rasteriser (stolen from cairo), which
does effectively the same job, but much faster.

For now, it turns out the easiest way to render polygons efficiently is
with masking, then you only need to rasterise each contour (which
doesn't have holes).

Peter Clifton

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

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

Attachment: signature.asc
Description: This is a digitally signed message part

geda-user mailing list