// -*- C -*- // suitable for masking things within radius sqrt(2) only module FArcSegment_mask(beta) { for (i=[0 : 0.75 : 3]) { rotate(i*beta/4) polygon([[0, 0], [1, 0], [cos(beta/4), sin(beta/4)]]); } } module FArcSegment(xc,yc,inrad,outrad,alpha,delta) { translate([xc,yc]) { intersection() { difference() { circle(r=outrad, $fn=70); circle(r=inrad, $fn=70); } rotate(alpha) scale(outrad*2) { FArcSegment_mask(delta); } } } }