PostGISで三角形を描画する - Qiita

/** * Create triangle geometry. * @param lon double precision center point WGS84 SRID:4326 * @param lat double precision WGS84 SRID:4326 * @param r double precision circumradius by the meter * @return geometry **/ CREATE OR REPLACE FUNCTION st_triangle( lon double precision, lat double precision , r double precision ) RETURNS geometry AS 'with t_plist(id,n)as ( values (1, 25 ) , (2, 4 ) , (3, 14 )