PostGIS 1.5.8 Manual - Fedora Project Packages GIT repositories

PostGIS 1.5.8 Manual134 / 310SELECT ST_AsText(ST_Segmentize(ST_GeomFromText(’POLYGON((-29 28, -30 40, -29 28))’),10));st_astext-----------------------POLYGON((-29 28,-29.8304547985374 37.9654575824488,-30 40,-29.1695452014626 ←↪30.0345424175512,-29 28))(1 row)See AlsoST_Line_Substring7.5.21 ST_SetPointST_SetPoint — Replace point N of linestring with given point. Index is 0-based.Synopsisgeometry ST_SetPoint(geometry linestring, integer zerobasedposition, geometry point);DescriptionReplace point N of linestring with given point. Index is 0-based. This is especially useful in triggers when trying to maintainrelationship of joints when one vertex moves.Availability: 1.1.0This function supports 3d and will not drop the z-index.Examples--Change first point in line string from -1 3 to -1 1SELECT ST_AsText(ST_SetPoint(’LINESTRING(-1 2,-1 3)’, 0, ’POINT(-1 1)’));st_astext-----------------------LINESTRING(-1 1,-1 3)---Change last point in a line string (lets play with 3d linestring this time)SELECT ST_AsEWKT(ST_SetPoint(foo.the_geom, ST_NumPoints(foo.the_geom) - 1, ST_GeomFromEWKT ←↪(’POINT(-1 1 3)’)))FROM (SELECT ST_GeomFromEWKT(’LINESTRING(-1 2 3,-1 3 4, 5 6 7)’) As the_geom) As foo;st_asewkt-----------------------LINESTRING(-1 2 3,-1 3 4,-1 1 3)See AlsoST_AddPoint,ST_NPoints, ST_NumPoints, ST_PointN, ST_RemovePoint7.5.22 ST_SetSRIDST_SetSRID — Sets the SRID on a geometry to a particular integer value.