A route may not leave a cell inside a wire keepout as a wire, nor reach
a pin there by one: it changes layer instead, and the via goes in the
pad. A pin whose every stub enters a keepout is reached by a via only.
A structure keepout named rule_area... (mckicad names KiCad rule areas
so) is checked for overlap only, as KiCad's DRC does, with the free ends
of each wire tested for their round caps.
A bounding-box spatial hash (broad phase) with exact IntBox-intersection
narrow phase, replacing the exact router's occupancy grid. Supports
insert/remove-owner and overlap/region queries, a clearance_conflict test
(strict 2-D overlap of the clearance-expanded box, so tiles exactly a
clearance apart are allowed), and has_violation for the whole-board DRC
check. Tiles are tagged routed vs static so pad-vs-pad spacing in the
source design is not counted as a routing violation.
rsp2k