---
--- 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 $$
-DECLARE
- lat CONSTANT DOUBLE PRECISION := scaled_lat / 10000000.0;
- lon CONSTANT DOUBLE PRECISION := scaled_lon / 10000000.0;
- zscale CONSTANT DOUBLE PRECISION := 2.0 ^ zoom;
- pi CONSTANT DOUBLE PRECISION := 3.141592653589793;
- r_per_d CONSTANT DOUBLE PRECISION := pi / 180.0;
- x int4;
- y int4;
-BEGIN
- -- straight port of the C code. see db/functions/maptile.c
- x := floor((lon + 180.0) * zscale / 360.0);
- y := floor((1.0 - ln(tan(lat * r_per_d) + 1.0 / cos(lat * r_per_d)) / pi) * zscale / 2.0);
-
- RETURN (x << zoom) | y;
-END;
-$$;
-
-