Re: gEDA-user: what does "Error while clipping PBO_SUB: 3" mean?

[Peter Clifton <pcjc2@xxxxxxxxx>]

On Wed, 2010-02-10 at 01:29 -0600, Mark Rages wrote:
> I'm trying to work with a rather compex polygon ground plane.  I get
> the following spew on the terminal, then crash:
> 
> Error while clipping PBO_SUB: 3
> Error while clipping PBO_SUB: 3
> Error while clipping PBO_SUB: 3
> Error while clipping PBO_SUB: 3
> Error while clipping PBO_SUB: 3
> Error while clipping PBO_SUB: 3
> Error while clipping PBO_SUB: 3
> Error while clipping PBO_SUB: 3
> Error while clipping PBO_SUB: 3
> Just leaked in Subtract
> Segmentation fault
> 
> Any ideas on where to look for the problem?

Such bugs are usually algorithmic issues in the polygon routines. Are
you by any chance using one of my experimental branches? (git HEAD also
suffers some of these issues, but I want to know whether it could be
something "extra".)

The code ought not to crash (even if it gets the polygons wrong), so if
you can get a gdb backtrace, that would be an excellent start.

Secondly, (also very important), if the problem is reproducible, take a
copy of the board with the issue, and start removing parts until the
problem goes away. Distilling a minimum test-case for the polygon code
is hard though - as it can depend on the exact order of operations.

Sometimes I've found you can't reproduce after removing component "X",
so you leave it in. Then, after removing component "Y" and "Z", you can
go back and remove "X" - whilst still being able to reproduce the bug.
Cutting down to a small test-case is time-consuming!

Best regards,

Peter C.



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