kicad-developers team mailing list archive

[jean-pierre charras - INPG <jean-pierre.charras@...>]

Dick Hollenbeck a écrit :
> Lorenzo wrote:
> > --- In kicad-devel@ yahoogroups. com 
> <mailto:kicad-devel%40yahoogroups.com>, Dick Hollenbeck <dick@...> wrote:
> >
> >> Then we need something more stable. I'd switch over to a 0 based index
> >> into the list of grid sizes, but maybe treat user size as special,
> >> assigning it -1, just so it does not get moved in the future if more
> >> sizes are added.
> >>
> >
> > What about the 'obvious' solution, i.e. just saving the grid size in 
> decimils like all the other things in pcbnew?
> >
> > Something like:
> >
> > GridSize 1000 1000
> >
> > for a 100mil grid...
> >
> > A lookup on the dozen or so predefined values is not so heavy (and 
> anyway is only done on load)
> >
>
> This is obvious, and quite agreeable. I'd like to have a grid offset in
> there too. See next posting.

Unfortunately, grid size cannot be handled in decimils.
In pcbnew grid is handled as double.
This is because for many grids values in mm, using a value rounded in 
decimils creates a cummulative error that can be important
(some mm for a 300 mm board)

So grid sizes must be given
- always in inches or decimils but using a floating point value, for non 
integer values as needed for metric grids
- or as an integer in decimils or um units and give the used unit (um ou 
decimil) as parameter
--
Jean-Pierre CHARRAS
Maître de conférences
Directeur d'études 2ieme année.
Génie Electrique et Informatique Industrielle 2
Institut Universitaire de Technologie 1 de Grenoble
BP 67, 38402 St Martin d'Heres Cedex

Recherche :
Grenoble Image Parole Signal Automatique (GIPSA - INPG)
Grenoble France