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-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
--
-- PostGIS - Spatial Types for PostgreSQL
-- http://postgis.net
--
-- Copyright (C) 2012 Sandro Santilli <strk@kbt.io>
--
-- This is free software; you can redistribute and/or modify it under
-- the terms of the GNU General Public Licence. See the COPYING file.
--
-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
--{
--
-- Return a list of edges (sequence, id) incident to the given node.
--
-- Edge ids are signed, they are negative if the node is their endpoint.
-- Sequence numbers start with 1 ordering edges by azimuth (clockwise).
--
-- GetNodeEdges(atopology, anode)
--
CREATE OR REPLACE FUNCTION topology.GetNodeEdges(atopology varchar, anode int)
RETURNS SETOF topology.GetFaceEdges_ReturnType
AS
$$
DECLARE
curedge int;
nextedge int;
rec RECORD;
retrec topology.GetFaceEdges_ReturnType;
n int;
sql text;
BEGIN
n := 0;
sql :=
'WITH incident_edges AS ( SELECT edge_id, start_node, end_node, ST_RemoveRepeatedPoints(geom) as geom FROM '
|| quote_ident(atopology)
|| '.edge_data WHERE start_node = ' || anode
|| ' or end_node = ' || anode
|| ') SELECT edge_id, ST_Azimuth(ST_StartPoint(geom), ST_PointN(geom, 2)) as az FROM incident_edges WHERE start_node = ' || anode
|| ' UNION ALL SELECT -edge_id, ST_Azimuth(ST_EndPoint(geom), ST_PointN(geom, ST_NumPoints(geom)-1)) FROM incident_edges WHERE end_node = ' || anode
|| ' ORDER BY az';
#ifdef POSTGIS_TOPOLOGY_DEBUG
RAISE DEBUG 'sql: %', sql;
#endif
FOR rec IN EXECUTE sql
LOOP -- incident edges {
#ifdef POSTGIS_TOPOLOGY_DEBUG
RAISE DEBUG 'Edge:% az:%', rec.edge_id, rec.az;
#endif
n := n + 1;
retrec.sequence := n;
retrec.edge := rec.edge_id;
RETURN NEXT retrec;
END LOOP; -- incident edges }
END
$$
LANGUAGE 'plpgsql' STABLE;
--} GetNodeEdges
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