sql

lib/sql/scripts-available/CDB_GreatCircle.sql

@@ -0,0 +1,26 @@
+-- Great circle point-to-point routes, based on:
+--   http://blog.cartodb.com/jets-and-datelines/
+--
+CREATE OR REPLACE FUNCTION @extschema@.CDB_GreatCircle(start_point @postgisschema@.geometry, end_point @postgisschema@.geometry, max_segment_length NUMERIC DEFAULT 100000)
+RETURNS @postgisschema@.geometry AS $$
+DECLARE
+  line @postgisschema@.geometry;
+BEGIN
+  line = @postgisschema@.ST_Segmentize(
+    @postgisschema@.ST_Makeline(
+      start_point,
+      end_point
+    )::geography,
+    max_segment_length
+  )::geometry;
+
+  IF @postgisschema@.ST_XMax(line) - @postgisschema@.ST_XMin(line) > 180 THEN
+    line = @postgisschema@.ST_Difference(
+      @postgisschema@.ST_ShiftLongitude(line),
+			@postgisschema@.ST_Buffer(@postgisschema@.ST_GeomFromText('LINESTRING(180 90, 180 -90)', 4326), 0.00001)
+		);
+  END IF;
+RETURN line;
+END;
+$$
+LANGUAGE 'plpgsql' IMMUTABLE STRICT PARALLEL SAFE;