AC A-shells overlapping B-shell at A-vertex POLYGON( (100 60, 140 100, 100 140, 60 100, 100 60)) MULTIPOLYGON( ( (80 40, 120 40, 120 80, 80 80, 80 40)), ( (120 80, 160 80, 160 120, 120 120, 120 80)), ( (80 120, 120 120, 120 160, 80 160, 80 120)), ( (40 80, 80 80, 80 120, 40 120, 40 80))) true true