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Use standard formula for CDB_ZoomFromScale

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postgis-vt-util comes with a standard formula for zoom from
scaleDenominator, and this is well tested. This also fixes the
function throwing an error on NULL input.
This commit is contained in:
Paul Norman
2016-02-08 22:45:27 -08:00
committed by Javier Goizueta
parent f5f59be5b0
commit aa302c237d
1 changed files with 11 additions and 29 deletions
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40
scripts-available/CDB_ZoomFromScale.sql
View File

@@ -1,30 +1,12 @@
CREATE OR REPLACE FUNCTION cartodb.CDB_ZoomFromScale(scaleDenominator numeric) RETURNS int AS $$
BEGIN
CREATE OR REPLACE FUNCTION cartodb.CDB_ZoomFromScale(scaleDenominator numeric)
RETURNS int
LANGUAGE SQL
IMMUTABLE
AS $$
SELECT
CASE
WHEN scaleDenominator > 500000000 THEN RETURN 0;
WHEN scaleDenominator <= 500000000 AND scaleDenominator > 200000000 THEN RETURN 1;
WHEN scaleDenominator <= 200000000 AND scaleDenominator > 100000000 THEN RETURN 2;
WHEN scaleDenominator <= 100000000 AND scaleDenominator > 50000000 THEN RETURN 3;
WHEN scaleDenominator <= 50000000 AND scaleDenominator > 25000000 THEN RETURN 4;
WHEN scaleDenominator <= 25000000 AND scaleDenominator > 12500000 THEN RETURN 5;
WHEN scaleDenominator <= 12500000 AND scaleDenominator > 6500000 THEN RETURN 6;
WHEN scaleDenominator <= 6500000 AND scaleDenominator > 3000000 THEN RETURN 7;
WHEN scaleDenominator <= 3000000 AND scaleDenominator > 1500000 THEN RETURN 8;
WHEN scaleDenominator <= 1500000 AND scaleDenominator > 750000 THEN RETURN 9;
WHEN scaleDenominator <= 750000 AND scaleDenominator > 400000 THEN RETURN 10;
WHEN scaleDenominator <= 400000 AND scaleDenominator > 200000 THEN RETURN 11;
WHEN scaleDenominator <= 200000 AND scaleDenominator > 100000 THEN RETURN 12;
WHEN scaleDenominator <= 100000 AND scaleDenominator > 50000 THEN RETURN 13;
WHEN scaleDenominator <= 50000 AND scaleDenominator > 25000 THEN RETURN 14;
WHEN scaleDenominator <= 25000 AND scaleDenominator > 12500 THEN RETURN 15;
WHEN scaleDenominator <= 12500 AND scaleDenominator > 5000 THEN RETURN 16;
WHEN scaleDenominator <= 5000 AND scaleDenominator > 2500 THEN RETURN 17;
WHEN scaleDenominator <= 2500 AND scaleDenominator > 1500 THEN RETURN 18;
WHEN scaleDenominator <= 1500 AND scaleDenominator > 750 THEN RETURN 19;
WHEN scaleDenominator <= 750 AND scaleDenominator > 500 THEN RETURN 20;
WHEN scaleDenominator <= 500 AND scaleDenominator > 250 THEN RETURN 21;
WHEN scaleDenominator <= 250 AND scaleDenominator > 100 THEN RETURN 22;
WHEN scaleDenominator <= 100 THEN RETURN 23;
END CASE;
END
$$ LANGUAGE plpgsql IMMUTABLE;
-- Don't bother if the scale is larger than ~zoom level 0
WHEN scaleDenominator > 600000000 OR scaleDenominator = 0 THEN NULL
ELSE CAST (ROUND(LOG(2, 559082264.028/scaleDenominator)) AS INTEGER)
END;
$$;