kicad-developers team mailing list archive

[Seth Hillbrand <seth@xxxxxxxxxxxxx>]

Hi Jeff-

Right now we do (a) except that we set the min-width to 1/2 the Eagle 
stroke width [1].  This is because we stroke inside the zone outline.  
Eagle rounds using the edge of their line, which is curved to 1/2 the 
width.

Best-
Seth

[1] 
https://git.launchpad.net/kicad/commit/?id=490c805319974ec84a8fbe8b10e9b59b9a3922a6

On 2019-07-14 16:13, Jeff Young wrote:
> Hi Seth,
>
> I’m still not following this.  When Eagle strokes the boundary, it
> does so with a round pen (at least going by the pngs in the bug
> report).  So all corners have a radius of 1/2 the stroke width.
>
> How do we currently represent that in Kicad?
> a) inflate the boundary by 1/2-eagle-stroke-width and set min-width to
> eagle-stroke-width?
> b) inflate the boundary by 1/2-eagle-stroke-width and set corner
> filleting to 1/2-eagle-stroke-width?
> c) inflate the boundary by 1/2-eagle-stroke-width and let Clipper
> round the corners?
>
> If it’s (c), I’m saying that doesn’t actually work. (Or at least it
> didn’t.)  You’re probably seeing the effects of (a), only with a
> default min-width so the radiuses won’t necessarily exactly match.
>
> I’ve changed (c) to also round by 1/2-min-width, so that it can be
> equivalent to (a) when “stroke-zone-boundaries” is off.
>
> Cheers,
> Jeff.
>
>
>
> > On 14 Jul 2019, at 20:21, Seth Hillbrand <seth@xxxxxxxxxxxxx> wrote:
> >
> > Hi Jeff-
> >
> > The bug was that Eagle strokes on the boundary.  We stroke inside.  
> > When we convert, we need to expand strictly as a square to get the 
> > equivalent KiCad zone.  Mitering and rounding will give excess polygon 
> > points.  The only way I have found to get this in Clipper is to use 
> > jtMiter and set the miterlimit to 0.  Oddly, just setting the 
> > parameter to jtSquare gave a mitered corner.
> >
> > It sounds from your description that you've changed this behavior in 
> > Clipper.  If that is the case, Eagle converted zones will no longer be 
> > correct.
> >
> > -Seth
> >
> > On 2019-07-14 14:22, Jeff Young wrote:
> > > Hi Seth,
> > > I looked at that bug report, and all the Eagle zones have rounded
> > > corners, not square.  So I don’t think you were actually getting
> > > anything out of the mitering, but that was being masked by the fact
> > > that we _do_ in fact stroke the outer zone boundary (therefore giving
> > > you rounded corners).
> > > Just to be clear, we stroke with the zone-min-width stroke, rather
> > > than the zone boundary’s linewidth.  We first deflate the zone by
> > > 1/2-min-width (which drops out all the min-width features), and then
> > > stroke it with min-width which expands it back to size and gives us
> > > some corner rounding as a bonus.
> > > JP has recently introduced a new mode where we don’t stroke the
> > > boundary anymore (I think primarily for performance, but I’m not
> > > 100% sure).  Under this algorithm we still deflate the zones by
> > > 1/2-min-width, but we then inflate them again to bring them back to
> > > size.  My changes are largely to add corner rounding to this case.
> > > Cheers,
> > > Jeff.
> > > > On 14 Jul 2019, at 18:53, Seth Hillbrand <seth@xxxxxxxxxxxxx> wrote:
> > > > Please be super careful here.  I was using that implicit fallback in
> > > > the Eagle import to get a square inflation that is needed to mimic
> > > > the Eagle zones.  I didn't think we were using that type of
> > > > inflation anywhere else (but that could have changed).  If we are
> > > > using that elsewhere, can you verify that the change to clipper
> > > > doesn't re-introduce https://bugs.launchpad.net/kicad/+bug/1817312 ?
> > > > Thanks-
> > > > Seth
> > > > On 2019-07-14 13:17, Jeff Young wrote:
> > > > Hi Seth,
> > > > We weren’t calling it directly anywhere.  But jtMiter has a
> > > > MiterLimit, after which it falls back to square.  I’ve changed
> > > > that
> > > > fallback to round (and enforced a much lower MiterLimit so that it
> > > > mimics the smoothing we used to get by drawing the border with a
> > > > 1/2-min-width thick stroke).
> > > > Cheers,
> > > > Jeff.
> > > > On 14 Jul 2019, at 17:50, Seth Hillbrand <seth@xxxxxxxxxxxxx> wrote:
> > > > On 2019-07-14 05:31, Jeff Young wrote:
> > > > I made another optimisation, this time within the Clipper library.
> > > > When the offset exceeds the MiterLimit it will perform jtRound
> > > > instead
> > > > of jtSquare.  I *think* this makes the zero-width-border algorithm
> > > > materially indistinguishable from the old algorithm (well, except
> > > > that
> > > > several bugs are fixed in the new one and it’s faster).
> > > > Hi Jeff-
> > > > Were we using jtSquare somewhere?  I had added an option to inflate
> > > > using jtMiter but this was for Eagle import only.  I thought all
> > > > other inflations were using jtRound.
> > > > Best-
> > > > Seth