convert_coasts_angle_to_vec(coastlines_poly_a &coastlines_a, coastlines_poly_v &coastlines_v)
	mapp(coastlines_a, coastlines_v, poly_angle3_to_poly_vec3)

dump_poly_angle3(const poly_angle3 &poly_a)
	for_each(poly_a, dump_angle3)
	#debug("\n")

# ----- sectors -----

struct clipped_region
	region &r
	vector<clip_to_sector_arc> arcs

struct sector_regions
	map<int,clipped_region> regions_clipped
	map<int,region*> regions_inside
	map<int,region*> regions_containing

# XXX do we need to worry about floating-point precision issues? rememeber the i386/?? `FP regs have extra precision' issue in gcc doc
#   maybe I could round everything to a certain fixed precision (e.g. 32 bits) before comparing?