But that 1.600 is not a double/floating number, it truncated from the double of 1.600000000000000088817841970012523233890533447265625
The entire complaint I believe is when it comes to serializing to JSON in 99% of software of all languages, you do not apply custom formatting to convert doubles to having less digits, you literally store the data type as is for what's considered a JSON "number". Otherwise we should be storing the float as string and applying the custom formatting in the conversion to string. On Sat, Dec 28, 2019 at 8:01 AM jp charras <jp.char...@wanadoo.fr> wrote: > > Le 24/12/2019 à 21:43, Jon Evans a écrit : > > OK, so both the JSON format itself and the Ucamco gerber format (which > > is not necessarily the same as the job file format, but hey) specify > > storing doubles. > > But, the examples in the Ucamco doc, and KiCad itself, do not store doubles. > > > > I have to imagine that the gerber job file format is so new that it > > isn't entrenched in anyone's workflow yet, and if it is, they are not > > relying on this quirk of KiCad's implementation (but anything is possible). > > The only way to get KiCad's behavior is through manual formatting of > > JSON, so anyone who writes software that parses job files through a JSON > > parsing library is going to have those values "upcasted" anyway. > > > > My personal opinion is that we should bite the bullet and change the > > behavior to comply with the standard (i.e. store doubles), and also > > suggest to Ucamco that they revise the job file spec to be more explicit > > about this. > > > > Perhaps JP should weigh in on this as well. > > > > -Jon > > Sorry for the delay. > > I am unsure to understand the meaning of > "KiCad itself do not store doubles" > (in gerber job files) > > A line like: > "BoardThickness": 1.600, > > stores a double: > AFAIK, "1.600" is of course a floating number, and also a double, not > an integer. > > In job files, most of values (board sizes, layers thickness, clearances) > are "mechanical" values. > > A reasonable precision is the micron for this kind of parameters. > > No need to use nanometers. > So values are written using 3 digits for the mantissa. > > Using the notation: > "BoardThickness": 1600e-3, > is perfectly valid, but useless and less readable. > > FYI, using 6 digits (1 nanometer) in other Gerber files is needed to > avoid coordinates truncation. > > 3 digits is certainly enough to fabricate a board. > Unfortunately, truncation slightly modify polygon coordinates, and this > truncation can (and frequently does) create self intersecting polygons. > (self intersecting polygons are illegal). > > -- > Jean-Pierre CHARRAS > > _______________________________________________ > Mailing list: https://launchpad.net/~kicad-developers > Post to : kicad-developers@lists.launchpad.net > Unsubscribe : https://launchpad.net/~kicad-developers > More help : https://help.launchpad.net/ListHelp -- Mark _______________________________________________ Mailing list: https://launchpad.net/~kicad-developers Post to : kicad-developers@lists.launchpad.net Unsubscribe : https://launchpad.net/~kicad-developers More help : https://help.launchpad.net/ListHelp
