27 lines
652 B
PL/PgSQL
27 lines
652 B
PL/PgSQL
-- Great circle point-to-point routes, based on:
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-- http://blog.cartodb.com/jets-and-datelines/
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--
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CREATE OR REPLACE FUNCTION CDB_GreatCircle(start_point geometry, end_point geometry, max_segment_length NUMERIC DEFAULT 100000)
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RETURNS geometry AS $$
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DECLARE
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line geometry;
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BEGIN
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line = ST_Segmentize(
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ST_Makeline(
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start_point,
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end_point
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)::geography,
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max_segment_length
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)::geometry;
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IF ST_XMax(line) - ST_XMin(line) > 180 THEN
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line = ST_Difference(
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ST_Shift_Longitude(line),
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ST_Buffer(ST_GeomFromText('LINESTRING(180 90, 180 -90)', 4326), 0.00001)
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);
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END IF;
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RETURN line;
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END;
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$$
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LANGUAGE 'plpgsql';
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