1 | -- |
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2 | -- Copyright (c) 2005 Sylvain Pasche, |
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3 | -- 2006-2007 Anton A. Patrushev, Orkney, Inc. |
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4 | -- |
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5 | -- This program is free software; you can redistribute it and/or modify |
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6 | -- it under the terms of the GNU General Public License as published by |
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7 | -- the Free Software Foundation; either version 2 of the License, or |
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8 | -- (at your option) any later version. |
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9 | -- |
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10 | -- This program is distributed in the hope that it will be useful, |
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11 | -- but WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 | -- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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13 | -- GNU General Public License for more details. |
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14 | -- |
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15 | -- You should have received a copy of the GNU General Public License |
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16 | -- along with this program; if not, write to the Free Software |
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17 | -- Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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18 | |
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19 | |
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20 | -- BEGIN; |
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21 | ---------------------------------------------------------- |
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22 | -- Draws an alpha shape around given set of points. |
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23 | -- |
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24 | -- Last changes: 14.02.2008 |
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25 | ---------------------------------------------------------- |
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26 | CREATE OR REPLACE FUNCTION points_as_polygon(query varchar) |
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27 | RETURNS SETOF GEOMS AS |
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28 | $$ |
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29 | DECLARE |
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30 | r record; |
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31 | path_result record; |
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32 | i int; |
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33 | q text; |
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34 | x float8[]; |
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35 | y float8[]; |
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36 | geom geoms; |
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37 | id integer; |
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38 | BEGIN |
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39 | |
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40 | id :=0; |
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41 | |
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42 | i := 1; |
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43 | q := 'select 1 as gid, GeometryFromText(''POLYGON(('; |
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44 | |
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45 | FOR path_result IN EXECUTE 'select x, y from alphashape('''|| |
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46 | query || ''')' LOOP |
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47 | x[i] = path_result.x; |
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48 | y[i] = path_result.y; |
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49 | i := i+1; |
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50 | END LOOP; |
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51 | |
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52 | q := q || x[1] || ' ' || y[1]; |
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53 | i := 2; |
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54 | |
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55 | WHILE x[i] IS NOT NULL LOOP |
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56 | q := q || ', ' || x[i] || ' ' || y[i]; |
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57 | i := i + 1; |
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58 | END LOOP; |
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59 | |
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60 | q := q || ', ' || x[1] || ' ' || y[1]; |
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61 | q := q || '))'',-1) as the_geom'; |
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62 | |
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63 | FOR r in EXECUTE q LOOP |
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64 | geom.gid=r.gid; |
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65 | geom.the_geom=r.the_geom; |
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66 | id := id+1; |
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67 | geom.id := id; |
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68 | RETURN NEXT geom; |
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69 | END LOOP; |
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70 | |
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71 | RETURN; |
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72 | END; |
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73 | $$ |
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74 | |
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75 | LANGUAGE 'plpgsql' VOLATILE STRICT; |
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76 | |
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77 | -- COMMIT; |
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