+--
+-- Name: maptile_for_point(bigint, bigint, integer); Type: FUNCTION; Schema: public; Owner: -
+--
+
+CREATE FUNCTION public.maptile_for_point(scaled_lat bigint, scaled_lon bigint, zoom integer) RETURNS integer
+ LANGUAGE plpgsql IMMUTABLE
+ AS $$
+DECLARE
+ lat CONSTANT DOUBLE PRECISION := scaled_lat / 10000000.0;
+ lon CONSTANT DOUBLE PRECISION := scaled_lon / 10000000.0;
+ zscale CONSTANT DOUBLE PRECISION := 2.0 ^ zoom;
+ pi CONSTANT DOUBLE PRECISION := 3.141592653589793;
+ r_per_d CONSTANT DOUBLE PRECISION := pi / 180.0;
+ x int4;
+ y int4;
+BEGIN
+ -- straight port of the C code. see db/functions/maptile.c
+ x := floor((lon + 180.0) * zscale / 360.0);
+ y := floor((1.0 - ln(tan(lat * r_per_d) + 1.0 / cos(lat * r_per_d)) / pi) * zscale / 2.0);
+
+ RETURN (x << zoom) | y;
+END;
+$$;
+
+
+--
+-- Name: tile_for_point(integer, integer); Type: FUNCTION; Schema: public; Owner: -
+--
+
+CREATE FUNCTION public.tile_for_point(scaled_lat integer, scaled_lon integer) RETURNS bigint
+ LANGUAGE plpgsql IMMUTABLE
+ AS $$
+DECLARE
+ x int8; -- quantized x from lon,
+ y int8; -- quantized y from lat,
+BEGIN
+ x := round(((scaled_lon / 10000000.0) + 180.0) * 65535.0 / 360.0);
+ y := round(((scaled_lat / 10000000.0) + 90.0) * 65535.0 / 180.0);
+
+ -- these bit-masks are special numbers used in the bit interleaving algorithm.
+ -- see https://graphics.stanford.edu/~seander/bithacks.html#InterleaveBMN
+ -- for the original algorithm and more details.
+ x := (x | (x << 8)) & 16711935; -- 0x00FF00FF
+ x := (x | (x << 4)) & 252645135; -- 0x0F0F0F0F
+ x := (x | (x << 2)) & 858993459; -- 0x33333333
+ x := (x | (x << 1)) & 1431655765; -- 0x55555555
+
+ y := (y | (y << 8)) & 16711935; -- 0x00FF00FF
+ y := (y | (y << 4)) & 252645135; -- 0x0F0F0F0F
+ y := (y | (y << 2)) & 858993459; -- 0x33333333
+ y := (y | (y << 1)) & 1431655765; -- 0x55555555
+
+ RETURN (x << 1) | y;
+END;
+$$;
+
+