sql

2020-07-12 16:08:49 +00:00
parent f164cccbbf
commit 8bfa9f5dc7
187 changed files with 13263 additions and 0 deletions
--- a/lib/sql/scripts-available/CDB_Hexagon.sql
+++ b/lib/sql/scripts-available/CDB_Hexagon.sql
@@ -0,0 +1,148 @@
+-- Return an Hexagon with given center and side (or maximal radius)
+CREATE OR REPLACE FUNCTION @extschema@.CDB_MakeHexagon(center GEOMETRY, radius FLOAT8)
+RETURNS GEOMETRY
+AS $$
+  SELECT @postgisschema@.ST_MakePolygon(@postgisschema@.ST_MakeLine(geom))
+    FROM
+    (
+      SELECT (@postgisschema@.ST_DumpPoints(@postgisschema@.ST_ExteriorRing(@postgisschema@.ST_Buffer($1, $2, 3)))).*
+    ) as points
+    WHERE path[1] % 2 != 0
+$$ LANGUAGE 'sql' IMMUTABLE STRICT PARALLEL SAFE;
+
+
+-- In older versions of the extension, CDB_HexagonGrid had a different signature
+DROP FUNCTION IF EXISTS @extschema@.CDB_HexagonGrid(GEOMETRY, FLOAT8, GEOMETRY);
+
+--
+-- Fill given extent with an hexagonal coverage
+--
+-- @param ext Extent to fill. Only hexagons with center point falling
+--            inside the extent (or at the lower or leftmost edge) will
+--            be emitted. The returned hexagons will have the same SRID
+--            as this extent.
+--
+-- @param side Side measure for the hexagon.
+--             Maximum diameter will be 2 * side.
+--
+-- @param origin Optional origin to allow for exact tiling.
+--               If omitted the origin will be 0,0.
+--               The parameter is checked for having the same SRID
+--               as the extent.
+--
+-- @param maxcells Optional maximum number of grid cells to generate;
+--                 if the grid requires more cells to cover the extent
+--                 and exception will occur.
+----
+-- DROP FUNCTION IF EXISTS CDB_HexagonGrid(ext GEOMETRY, side FLOAT8);
+CREATE OR REPLACE FUNCTION @extschema@.CDB_HexagonGrid(ext GEOMETRY, side FLOAT8, origin GEOMETRY DEFAULT NULL, maxcells INTEGER DEFAULT 512*512)
+RETURNS SETOF GEOMETRY
+AS $$
+DECLARE
+  h GEOMETRY; -- hexagon
+  c GEOMETRY; -- center point
+  rec RECORD;
+  hstep FLOAT8; -- horizontal step
+  vstep FLOAT8; -- vertical step
+  vstart FLOAT8;
+  vstartary FLOAT8[];
+  vstartidx INTEGER;
+  hskip BIGINT;
+  hstart FLOAT8;
+  hend FLOAT8;
+  vend FLOAT8;
+  xoff FLOAT8;
+  yoff FLOAT8;
+  xgrd FLOAT8;
+  ygrd FLOAT8;
+  srid INTEGER;
+BEGIN
+
+  --            |     |     
+  --            |hstep|
+  --  ______   ___    |    
+  --  vstep  /     \ ___ /
+  --  ______ \ ___ /     \  
+  --         /     \ ___ / 
+  --
+  --
+  RAISE DEBUG 'Side: %', side;
+
+  vstep := side * sqrt(3); -- x 2 ?
+  hstep := side * 1.5;
+
+  RAISE DEBUG 'vstep: %', vstep;
+  RAISE DEBUG 'hstep: %', hstep;
+
+  srid := ST_SRID(ext);
+
+  xoff := 0; 
+  yoff := 0;
+
+  IF origin IS NOT NULL THEN
+    IF @postgisschema@.ST_SRID(origin) != srid THEN
+      RAISE EXCEPTION 'SRID mismatch between extent (%) and origin (%)', srid, ST_SRID(origin);
+    END IF;
+    xoff := @postgisschema@.ST_X(origin);
+    yoff := @postgisschema@.ST_Y(origin);
+  END IF;
+
+  RAISE DEBUG 'X offset: %', xoff;
+  RAISE DEBUG 'Y offset: %', yoff;
+
+  xgrd := side * 0.5;
+  ygrd := ( side * sqrt(3) ) / 2.0;
+  RAISE DEBUG 'X grid size: %', xgrd;
+  RAISE DEBUG 'Y grid size: %', ygrd;
+
+  -- Tweak horizontal start on hstep*2 grid from origin 
+  hskip := ceil((@postgisschema@.ST_XMin(ext)-xoff)/hstep);
+  RAISE DEBUG 'hskip: %', hskip;
+  hstart := xoff + hskip*hstep;
+  RAISE DEBUG 'hstart: %', hstart;
+
+  -- Tweak vertical start on hstep grid from origin 
+  vstart := yoff + ceil((@postgisschema@.ST_Ymin(ext)-yoff)/vstep)*vstep; 
+  RAISE DEBUG 'vstart: %', vstart;
+
+  hend := @postgisschema@.ST_XMax(ext);
+  vend := @postgisschema@.ST_YMax(ext);
+
+  IF vstart - (vstep/2.0) < @postgisschema@.ST_YMin(ext) THEN
+    vstartary := ARRAY[ vstart + (vstep/2.0), vstart ];
+  ELSE
+    vstartary := ARRAY[ vstart - (vstep/2.0), vstart ];
+  END IF;
+
+  If maxcells IS NOT NULL AND maxcells > 0 THEN
+    IF CEIL((CEIL((vend-vstart)/(vstep/2.0)) * CEIL((hend-hstart)/(hstep*2.0/3.0)))/3.0)::integer > maxcells THEN
+      RAISE EXCEPTION 'The requested grid is too big to be rendered';
+    END IF;
+  END IF;
+
+  vstartidx := abs(hskip)%2;
+
+  RAISE DEBUG 'vstartary: % : %', vstartary[1], vstartary[2];
+  RAISE DEBUG 'vstartidx: %', vstartidx;
+
+  c := @postgisschema@.ST_SetSRID(@postgisschema@.ST_MakePoint(hstart, vstartary[vstartidx+1]), srid);
+  h := @postgisschema@.ST_SnapToGrid(@extschema@.CDB_MakeHexagon(c, side), xoff, yoff, xgrd, ygrd);
+  vstartidx := (vstartidx + 1) % 2;
+  WHILE @postgisschema@.ST_X(c) < hend LOOP -- over X
+    --RAISE DEBUG 'X loop starts, center point: %', ST_AsText(c);
+    WHILE @postgisschema@.ST_Y(c) < vend LOOP -- over Y
+      --RAISE DEBUG 'Center: %', ST_AsText(c);
+      --h := ST_SnapToGrid(CDB_MakeHexagon(c, side), xoff, yoff, xgrd, ygrd);
+      RETURN NEXT h;
+      h := @postgisschema@.ST_SnapToGrid(ST_Translate(h, 0, vstep), xoff, yoff, xgrd, ygrd);
+      c := @postgisschema@.ST_Translate(c, 0, vstep);  -- TODO: drop ?
+    END LOOP;
+    -- TODO: translate h direcly ...
+    c := @postgisschema@.ST_SetSRID(@postgisschema@.ST_MakePoint(ST_X(c)+hstep, vstartary[vstartidx+1]), srid);
+    h := @postgisschema@.ST_SnapToGrid(@extschema@.CDB_MakeHexagon(c, side), xoff, yoff, xgrd, ygrd);
+    vstartidx := (vstartidx + 1) % 2;
+  END LOOP;
+
+  RETURN;
+END
+$$ LANGUAGE 'plpgsql' IMMUTABLE PARALLEL SAFE;