Hi Rafał,
Thanks for your reply.
*
*
> Guys, have you ever considered going to "virtual dimensions"?
I think it's not doable.
Because you need to show the same thing with different units when using
pcb editor.
For example:
1. Users want to change the display unit from one to another.
2. Imported dxf shapes with specified unit
Sincerely
Liang
On Tue, 26 Nov 2024 at 13:06, Rafał Pietrak <[email protected]
<mailto:[email protected]>> wrote:
Guys, have you ever considered going to "virtual dimensions"?
What I mean here is that the entire design (that is the PCB of course,
not the SCH) is based on an integer grid like "natural numbers indices
to locations", while the grid size is provided for the entire PCB as a
single float?
Consequently, the current 32bit integers stay as they are, only their
meaning changes. They would no longer mean "mm" (or whatever
"physical"), but just "indecies". "Physical sizes" would emerge only
when pcb get converted to production (gerber?) files ... or whenever
user puts in new constraints. The later naturally should be accepted in
physical dimensions as they are specified by fabs, but for the design
within KiCAD they should be converted to "grid size" based on current
grid size. Same goes for shapes libraries, but I think its doable.
Such approach would introduce a "one time rounding errors" to the
design, but since this is really a "one time event" it does not bare
any
cumulative effects, so it shouldn't matter at all.
-R
On 26.11.2024 04:25, Liang Jia wrote:
> Hi Mark and Seth,
>
> Thanks for your reply.
>
> Yes, you're right, it will lose some precision when using double.
>
> Just curious, I did some search online.
> *1. I found that the key players in the PCB market still have
limits.*
> OrCAD X: 200 in. x 200 in = 5 meter * 5 meter;
> https://www.cadence.com/en_US/home/tools/pcb-design-and-analysis/
<https://www.cadence.com/en_US/home/tools/pcb-design-and-analysis/>
> orcad.html#pcb-layout <https://www.cadence.com/en_US/home/tools/
pcb- <https://www.cadence.com/en_US/home/tools/pcb->
> design-and-analysis/orcad.html#pcb-layout>
> Altium Designer: 200 in. x 200 in = 2.5 meter * 2.5 meter
> https://www.altium.com/documentation/knowledge-base/altium-
designer/ <https://www.altium.com/documentation/knowledge-base/
altium-designer/>
> indicate-visual-cues-at-the-coordinate-limit-of-pcb-design-space-
beyond-
> which-objects-should-not-be-placed <https://www.altium.com/
<https://www.altium.com/>
> documentation/knowledge-base/altium-designer/indicate-visual-
cues-at-
> the-coordinate-limit-of-pcb-design-space-beyond-which-objects-
should-
> not-be-placed>
> Allegro: I can't find any detail information, but I tried the
software,
> it seems still have limit. *Anyone know the board size limit for
Allegro?*
> *
> *
> *2. If we really want to solve this problem, there are options
below.*
> 2.1 Using software integer library, such as GMP;
> We can give an option to the user, let the user choose to
enable
> it or not.
> If enabled, Kicad can support a bigger board size, but
software
> will slow;
> If enabled, Kicad runs as usual.
> **https://gmplib.org/ <https://gmplib.org/> <https://gmplib.org/
<https://gmplib.org/>>
> 2.2 Using Binary coded-decimal,
> https://stackoverflow.com/questions/2624973/why-doesnt-my-
processor- <https://stackoverflow.com/questions/2624973/why-doesnt-
my-processor->
> have-built-in-bigint-support <https://stackoverflow.com/
<https://stackoverflow.com/>
> questions/2624973/why-doesnt-my-processor-have-built-in-bigint-
support>
> https://en.wikipedia.org/wiki/Binary-coded_decimal <https://
en.wikipedia.org/wiki/Binary-coded_decimal> <https://
> en.wikipedia.org/wiki/Binary-coded_decimal <http://
en.wikipedia.org/wiki/Binary-coded_decimal>>
> 2.3 *Give the control of precision and board size to the user.*
> If a user wants to have a smaller board size, he/she will
have
> more precision location and something else;
> If a user wants to have a bigger board size, he/she will have
> less precision location and something else;
>
> *@Mark what's your opinion? *
> *
> *
> *@Seth,
> *
> >Addressing this means reworking our internal coordinate system
> Could you please kindly give me some location for those codes? so
I can
> dig into it.
> *
> *
>
> Sincerely
> Liang
>
> On Tue, 26 Nov 2024 at 02:02, Mark Roszko <[email protected]
<mailto:[email protected]>
> <mailto:[email protected] <mailto:[email protected]>>> wrote:
>
> Floats are not accurate beyond 6-7 digits and worse, floating
point
> behavior is actually not fully well defined. You can actually get
> different quirks depending on platform, compiler and arch. Though
> generally the risk isn't in the arithmetic but supporting
functions
> that are part of libc.
>
> >And why did Kicad choose integer as internal measurement
resolution?
>
> Using integers is standard programming behavior for applications
> that want well defined and bounded mathematical behavior.
>
> When you do floating point math, even if we ignore the inaccurate
> power part of the number, that error still sits in the
number. When
> you carry out sufficient and numerous operations using
numbers that
> carry these not used digits, they can actually creep in and start
> affecting the digits you do care about and cause errors.
>
>
> >Last, so that means there is no way to handle this issue?
>
>
> We have come to the conclusion that if somebody needs PCB designs
> larger than 4 meters, which is already an ridiculous size.
They need
> to discuss with us the use case which is already going to be
> ridiculously niche for that one person because there is no
standard
> PCB manufacturing equipment for a board of that size.
>
>
> On Mon, Nov 25, 2024, 8:01 AM Liang Jia
<[email protected] <mailto:[email protected]>
> <mailto:[email protected]
<mailto:[email protected]>>> wrote:
>
> Hi Mark,
>
> Thanks for your email.
>
> Could you please explain more about the relation between
"Change
> the measurement store from 32-bit to *64-bit*" and "128-bit
> integer math support in processors"?
> And why did Kicad choose integer as internal measurement
resolution?
>
> >mm is not adequate to express the resolution of
position data
> required for a board design.
> How about this? use mm for internal measurement
resolution, but
> use nanometer or *double(instead of integer)* for board
design.
>
>
> Last, so that means there is no way to handle this issue?
>
> On Mon, 25 Nov 2024 at 19:21, Mark Roszko
<[email protected] <mailto:[email protected]>
> <mailto:[email protected]
<mailto:[email protected]>>> wrote:
>
> >This means it is possible to create boards up to
> approximately 4 meters by 4 meters
>
> Yes, KiCad is limited to 4x4 meter boards currently.
>
> > Change the measurement store from 32-bit to 64-
bit, so
> Kicad can support a larger board.
>
> This is not an easy task in the slightest. Specifically
> because we can't get 128-bit integer math support in
> processors, and many compilers do not support 128-bit
> integers. I think gcc has some experimental support.
>
> > Change the resolution of all objects to mm
>
> mm is not adequate to express the resolution of position
> data required for a board design.
>
>
>
> Basically the bug here is we simply do not tell the users
> the DXF is beyond our board support limit.
>
>
> On Mon, Nov 25, 2024 at 5:07 AM Liang Jia
> <[email protected]
<mailto:[email protected]>
> <mailto:[email protected]
<mailto:[email protected]>>> wrote:
>
> Hi All,
>
> I am writing to inquire about the challenges we are
> facing when importing DXF files which contain large
> numbers into our system.
>
> I have noticed that when the number exceeds a certain
> threshold(such as 4437 mm), the import process
results
> in an int overflow error.
>
> I did the search below:
> 1. Found that there was a ticket to track it, but it
> seems *it still opens*.
> https://gitlab.com/kicad/code/kicad/-/issues/12392 <https://
gitlab.com/kicad/code/kicad/-/issues/12392>
> <https://gitlab.com/kicad/code/kicad/-/
issues/12392 <https://gitlab.com/kicad/code/kicad/-/issues/12392>>
>
> 2. From the Kicad document:
> The internal measurement resolution of all objects in
> KiCad is *1 nanometer*, and measurements are
stored as
> *32-bit integers*. This means it is possible to
create
> boards up to approximately 4 meters by 4 meters
> I think the *root cause* is here: Kicad tried to
convert
> the DXF number into nanometer, but those numbers
> exceeded the limit of integer.
>
> Questions:
> 1. Is there any workaround for this case, and let
Kicad
> import those files successfully?
> 2. If I want to fix ticket 12392, what should I do?
> Change the measurement store from 32-bit to
64-bit,
> so Kicad can support a larger board.
> Change the resolution of all objects to mm
>
> Looking forward to any comment or workaround.
>
> Sincerely
> Liang
>
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