kicad-developers team mailing list archive

[Jeff Young <jeff@xxxxxxxxx>]

I did a bit more digging around, and as far as I can tell our current implementation is (c).

I think we need to move it to (a).  Eurocircuits (at least) says to use Eagle’s polygon boundary width to control necking (ie: Kicad's zone-min-width).  Eagle doesn’t appear to have any other parameter which controls that.

> On 14 Jul 2019, at 21:13, Jeff Young <jeff@xxxxxxxxx> 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
> 
> 
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