kicad-developers team mailing list archive

[Cirilo Bernardo <cirilo.bernardo@xxxxxxxxx>]

Hi Seth,
  What you have on the w3 site is essentially an interpretation by the
author of that page;
the spec referred to reads differently. At any rate, that doesn't change
the fact that existing
software for creating VRML (including Wings3D that many KiCad users used
long ago)
don't use a unit of 1m - and it all really comes back to the spec being
poorly worded and
various implementers interpreting it differently. If it sounds like I'm
being pedantic it's
because I've implemented too many standards specs over the years and
suffered
poor implementations even on points where I thought the language was clear.


On Wed, Sep 30, 2020 at 8:58 AM Seth Hillbrand <seth@xxxxxxxxxxxxx> wrote:

> I don't follow your statement.  The standard says "ISO/IEC 14772 defines
> the unit of measure of the world coordinate system to be metres."  There is
> no ambiguity here, so I would feel comfortable with saying that KiCad also
> defines the VRML standard unit to be meters (metres).
>
> As to the file savings, this is easily addressed by defining a single, new
> coordinate system in inches or microns that scales the global system.  All
> units in the file are then in scaled coordinates.
>
> -Seth
>
> On Tue, Sep 29, 2020 at 3:50 PM Cirilo Bernardo <cirilo.bernardo@xxxxxxxxx>
> wrote:
>
>> That's the same reference - the problem is with the wording 'is', not
>> 'shall' or 'must be'.
>> The reality is that for every tool you pick that generates VRML models,
>> the unit used is
>> anyone's guess.  On top of that, for KiCad's purposes using meters would
>> actually
>> be a nuisance and would unnecessarily bloat the VRML file. Many parts
>> often have
>> features on the order of 10 microns; using mm or even 0.1 inches shaves
>> off a lot of
>> zeroes (or repetitive exponents).
>>
>> Cirilo
>>
>>
>> On Wed, Sep 30, 2020 at 7:40 AM Seth Hillbrand <seth@xxxxxxxxxxxxx>
>> wrote:
>>
>>>
>>>
>>> On Tue, Sep 29, 2020 at 2:33 PM Cirilo Bernardo <
>>> cirilo.bernardo@xxxxxxxxx> wrote:
>>>
>>>> Oh, I wish VRML specified meters - that would have made life much
>>>> easier.
>>>>
>>>
>>> See
>>> https://www.web3d.org/documents/specifications/14772/V2.0/part1/concepts.html#4.4.5
>>> This reads pretty clear to me.  Was there a different reference you are
>>> referring to?
>>>
>>> -Seth
>>>
>>> --
>>> [image: KiCad Services Corporation Logo]
>>> Seth Hillbrand
>>> *Lead Developer*
>>> +1-530-302-5483‬ <+12126039372>
>>> Davis, CA
>>> www.kipro-pcb.com    info@xxxxxxxxxxxxx
>>>
>>
>
> --
> [image: KiCad Services Corporation Logo]
> Seth Hillbrand
> *Lead Developer*
> +1-530-302-5483‬ <+12126039372>
> Davis, CA
> www.kipro-pcb.com    info@xxxxxxxxxxxxx
>