kicad-developers team mailing list archive

[Cirilo Bernardo <cirilo.bernardo@xxxxxxxxx>]

On Tue, Jan 19, 2016 at 5:14 AM, Bernhard Stegmaier <stegmaier@xxxxxxxxxxxxx
> wrote:

> Hi,
>
> I didn’t try(check it, so maybe just dumb questions:
> What is the difference between the cached and original files?
> I guess most of the time the config folder will be on the same storage as
> the original files (== home folder), so what’s the point of copying them to
> a cache folder?
> It would probably make sense to be able to configure the cache folder (or
> use sth like $XDG_CACHE_HOME), so it could be directed to e.g. a tmpfs in
> RAM.
>
>
The cache files are a binary format and are an intermediate data
representation.
The existing scheme for 3D models is to parse them and put data into an
S3D_MASTER object. The translated data is not suitable for caching and
each instance of the same model file takes up more and more memory.
With the intermediate format each model is loaded only once so less memory
is used. In foreseeable future cases the intermediate format will also make
the subsequent model load times much faster in cases where creating the
display data is a compute-intensive operation, for example with rendering
MCAD data. The intermediate representation also means that each 3D
model plugin must translate to this one common data format which is
understood by the cache system; this also makes it possible to implement
a VRML output without much additional code since there is now a single
point of translation from intermediate format to VRML. In the legacy scheme
this would have been very messy to implement with each parser
implementing its own translator and VRML export routines - the parsers would
essentially be translating the model twice (once to S3D_MASTER then again
to VRML).

The cache file also speeds up model loading because it stores its own
computed normals. In our collection of VRML models I have noticed that
in the majority of cases there is either no normals data or the normals
data is bad. In the 3D plugin implementation all normals are calculated;
at this point I can't think of a scheme to select between calculated and
in-model normals on a per-model basis. Perhaps we can make such a
refinement in the future.

You can always link your cache directory to a RAMFS if you wish.

- Cirilo


>
> Regards,
> Bernhard
>
> > On 18 Jan 2016, at 19:02, Mário Luzeiro <mrluzeiro@xxxxx> wrote:
> >
> > Hi,
> >
> > For a) I think for this cache mechanisms there should be some way to
> versioning the files or folders or what.. so it will be automatically
> possible to the application to delete that files.
> > A possibility would be to hash the file with his own version, so a
> future version will create a different hash.. and maybe there is need for a
> size limit of the folder..
> >
> > Just some ideas..
> >
> > Mario
> >
> > ________________________________________
> > From: Kicad-developers [kicad-developers-bounces+mrluzeiro=
> ua.pt@xxxxxxxxxxxxxxxxxxx] on behalf of Clemens Koller [cko@xxxxxxxxx]
> > Sent: 18 January 2016 11:06
> > To: kicad-developers@xxxxxxxxxxxxxxxxxxx
> > Subject: Re: [Kicad-developers] 3D refactor update
> >
> > Hello, Cirilo!
> >
> > On 2016-01-18 09:59, Cirilo Bernardo wrote:
> >> I have reworked the new 3D code and would appreciate some
> testing/feedback
> >> Those who have tried previous versions will need to:
> >> a. delete all cache files (in the kicad config. directory under
> 3d/cache) and
> >> b. delete the older 3D search path list (in the kicad config. dir
> 3d/3Dresolver.cfg)
> >
> > What happens if somebody forgets to delete these files upfront?
> > Are these two steps also necessary in the production version later on?
> >
> > Regards,
> >
> > Clemens
> >
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>
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