AddFace
Name
AddFace — Registers a face primitive to a topology and gets its identifier.
Synopsis
integer
AddFace
(
varchar
toponame
, geometry
apolygon
, boolean
force_new=false
)
;
Description
Registers a face primitive to a topology and gets its identifier.
For a newly added face, the edges forming its boundaries and the ones contained in the face will be updated to have correct values in the left_face and right_face fields. Isolated nodes contained in the face will also be updated to have a correct containing_face field value.
The target topology is assumed to be valid (containing no self-intersecting edges). An exception is raised if: The polygon boundary is not fully defined by existing edges or the polygon overlaps an existing face.
If the
apolygon
geometry already exists as a face, then:
if
force_new
is false (the default) the
face id of the existing face is returned;
if
force_new
is true a new id will be assigned to
the newly registered face.
The
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Availability: 2.0.0
Examples
-- first add the edges we use generate_series as an iterator (the below -- will only work for polygons with < 10000 points because of our max in gs) SELECT topology.AddEdge('ma_topo', ST_MakeLine(ST_PointN(geom,i), ST_PointN(geom, i + 1) )) As edgeid FROM (SELECT ST_NPoints(geom) AS npt, geom FROM (SELECT ST_Boundary(ST_GeomFromText('POLYGON((234896.5 899456.7,234914 899436.4,234946.6 899356.9,234872.5 899328.7, 234891 899285.4,234992.5 899145, 234890.6 899069,234755.2 899255.4, 234612.7 899379.4,234776.9 899563.7,234896.5 899456.7))', 26986) ) As geom ) As geoms) As facen CROSS JOIN generate_series(1,10000) As i WHERE i < npt; -- result -- edgeid -------- 3 4 5 6 7 8 9 10 11 12 (10 rows) -- then add the face - SELECT topology.AddFace('ma_topo', ST_GeomFromText('POLYGON((234896.5 899456.7,234914 899436.4,234946.6 899356.9,234872.5 899328.7, 234891 899285.4,234992.5 899145, 234890.6 899069,234755.2 899255.4, 234612.7 899379.4,234776.9 899563.7,234896.5 899456.7))', 26986) ) As faceid; -- result -- faceid -------- 1