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Re: gEDA-user: Thermals on Pads

On 1/30/2011 3:39 PM, Peter Clifton wrote:
On Sun, 2011-01-30 at 21:12 +0100, Martin Kupec wrote:
On Sun, Jan 30, 2011 at 12:54:23PM -0700, asomers@xxxxxxxxx wrote:
I'm a novice to the pcb code base, and I couldn't find much developer
documentation, but I am willing to try to add this feature.  I need a
little help though: the pcb code base is too large for me to grok all
at once.  Could someone please tell me where to start?  What would I
have to modify to allow this?
Actualy, there already is a patch.
It can be found here: https://bugs.launchpad.net/pcb/+bug/699495

This patch has some issues as mentioned in the bug report, but it should
be usable.

I am willing to fix and extend the patch, but I do have exams period(or
how is the english word for it) :-(
I should be on that issue in few weeks(like 2-3).
I've been looking at some brokenness with our normal thermal shape
generation recently, so if I get a chance I could look at your patch -
and possibly work from it.

The main problem I have is not code, but deciding what such geometry
needs to look like it and how to specify it. Whatever we decide we have
to live with, as we can't go changing geometry on users with existing

That is the problem I'm hitting now. Harry's clipper branch (a long time
ago) without comment, changed the thermal generation formulas in (IMO, a
retrograde way). I can't change it back (or fix the geometry
calculation) for fear of possibly breaking all the users who have made
boards since then.

What geometry problems do you have? There are plenty of references in regard to thermals. I don't recall seeing any other than bridges that span a uniform gap around the pad. The only variation I can recall is the number and rotation angle of the pattern. But most, if not all that I have seen use four bars either along the x and y axes or at 45 degree angles. I think there are even some built in commands for this in the RS-274X Gerber file spec.

Or am I missing something?


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