kicad-developers team mailing list archive

[Cirilo Bernardo <cirilo.bernardo@xxxxxxxxx>]

In addition to that, the error in the approximation can be made as small as
we wish and it's not difficult to achieve <1 micron error if you really want
Gerber outputs to be that precise. This is "approximation" in the
mathematical
sense and not in the general use of the language, so we control the error.

- Cirilo

On Fri, Sep 16, 2016 at 11:37 PM, Nick Østergaard <oe.nick@xxxxxxxxx> wrote:

> What was mentiomed was to approximate for example beziers with arcs. That
> would still be accurate when exported to gerbers, because one could use
> arcs which are supported in gerbers IIRC.
>
> Den 16/09/2016 15.34 skrev "Wayne Stambaugh" <stambaughw@xxxxxxxxx>:
>
>> I would like to see arc support in copper layers as well but we need to
>> approach this carefully.  One thing KiCad has been pretty good at is not
>> producing broken gerber files.  A lot of code would have to be written
>> to support this fully.  When I here words like "approximate", it makes
>> me nervous.  Gerber output, particularly copper layers should not be
>> approximations, they need to be accurate down the accuracy of the gerber
>> plot formatting.
>>
>> On 9/14/2016 8:37 AM, Nick Østergaard wrote:
>> > Yes, of course arcs are more important. But Cirilo mentioned that one
>> > could use arcs to appromimate the beiziers for DRC and gerber
>> > generation purposes
>> >
>> > 2016-09-14 13:44 GMT+02:00 José Ignacio <jose.cyborg@xxxxxxxxx>:
>> >> I don't see length matching splines to be any easier than length
>> >> matching polylines. If anything having arcs is a lot more important
>> >> than beziers as arcs can form circles while beziers can't exactly (you
>> >> need NURBS for that). Also iirc Gerbers support arcs natively so it
>> >> would end up generating better output.
>> >>
>> >> On Wed, Sep 14, 2016 at 6:16 AM, Simon Wells <swel024@xxxxxxxxx>
>> wrote:
>> >>> i have no idea whether it is actually valid but could/would bezier
>> >>> curves be used in differential pairs that are also length matched? so
>> >>> that it would keep the seperation for the differential but would also
>> >>> allow the lengths to be equal?
>> >>>
>> >>> On Wed, Sep 14, 2016 at 10:51 PM, jp charras <jp.charras@xxxxxxxxxx>
>> wrote:
>> >>>>> On Wed, Sep 14, 2016 at 7:44 PM, Nick Østergaard <oe.nick@xxxxxxxxx
>> <mailto:oe.nick@xxxxxxxxx>> wrote:
>> >>>>>
>> >>>>>     For some RF applications people would like to use curves for
>> traces. So DRC support for
>> >>>>>     beizier/arcs would be nice here.
>> >>>>
>> >>>> I perfectly understand the interest of arcs in traces.
>> >>>>
>> >>>> But what the interest of Bezier curves in traces or shapes on copper
>> layers ?
>> >>>>
>> >>>> I am not a microwave specialist, however I never saw cases where
>> Bezier curves are needed.
>> >>>>
>> >>>> The more complex case I know is a filter, which works fine with
>> polygons (seen demos/microwave).
>> >>>>
>> >>>> AFAIK, complex shapes are generated by specialized tools (you cannot
>> easily draw them by hand).
>> >>>> Are they generating shapes with Bezier curves.
>> >>>>
>> >>>> Moreover, remember Gerber format does not support Bezier curves, so
>> they will be converted to
>> >>>> polygons if they are supported by Pcbnew.
>> >>>>
>> >>>> --
>> >>>> Jean-Pierre CHARRAS
>> >>>>
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>>
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