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Square Buffer
Thursday June 16 2011 at 09:56
I was asked the other day how to create a square buffer around a linestring (or set of linestrings).
select sdo_geom.validate_geometry(c.geom,0.005) as validPoly, c.geom
from (select sdo_geometry(2003,null,null,sdo_elem_info_array(1,1003,1),b.geom.sdo_ordinates) as geom
from (select sdo_util.append(geom,
sdo_geometry(2001,null,sdo_point_type(t.x,t.y,null),null,null)) as geom
from (select sdo_util.append(sdo_geometry(2002,null,null,sdo_elem_info_array(1,2,1),sdo_ordinate_array(10,0,10,100)),
sdo_util.reverse_linestring(
sdo_geometry(2002,null,null,sdo_elem_info_array(1,2,1),sdo_ordinate_array(-10,0,-10,100))))
as geom
from dual ) a,
table(sdo_util.getVertices(a.geom)) t
where t.id = 1
) b
) c;
If you used my parallel function, then everything could be achieved as follows:
select sdo_geom.validate_geometry(c.geom,0.005) as validPoly, c.geom
from (select sdo_geometry(2003,null,null,sdo_elem_info_array(1,1003,1),b.geom.sdo_ordinates) as geom
from (select mdsys.sdo_util.append(geom,
sdo_geometry(2001,null,sdo_point_type(t.x,t.y,null),null,null)) as geom
from (select sdo_util.append(codesys.geom.parallel(a.geom,10,0.05),
mdsys.sdo_util.reverse_linestring(
codesys.geom.parallel(a.geom,-10,0.05)))
as geom
from my_linestrings l
) a,
table(mdsys.sdo_util.getVertices(a.geom)) t
where t.id = 1
) b
) c;
Putting a PL/SQL function wrapper around this is trivial.
I hope this helps someone.
        
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