pcb-rnd - the [mincut] patch
+ +The original code was highlighting pins/pads only when a short came around +after rats nest optimization. This was not very helpful on a complex board. +There had been a long discussion on the mailing list about the best solutions. +There were a few very good ideas, including: +-
+
- manual tagging of objects (lines, polys, arcs, vias) with net and warn + where two differently tagged net connects +
- automatic tagging based on "where it was connected first", then the same + warning mechanism as above +
- trace history (using the undo buffer?) and go back until when it was + not broken, check what exactly broke it +
- history combined with tagging +
- calculate minimal cut +
+I choose minimal cut for my patch because it doesn't require tracing the +full history or any manual administration of nets vs. objects (which I +would find inevitable even with manual tagging - directly or indirectly +the user needs to be able to change net tags). +
+The minimal cut is the least amount of object whose removal would resolve +the short. It is best demonstrated on an example: +
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+Removing all the marked lines/polys/vias would surely resolve the short +(sometimes leaving rat lines behind). Minimal cut is better than randomly +removing objects, tho: it guarantees that the minimal amount of objects +are to be removed. On a complex board, this plave is likely to be close +to the place where the problem really is - much closer than the pins/pads. + + +