Name
CG_YMonotonePartition — Computes y-monotone partition of the polygon geometry
Synopsis
geometry CG_YMonotonePartition(geometry geom);
Description
Computes y-monotone partition of the polygon geometry.
![[Note]](../images/note.png)
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A partition of a polygon P is a set of polygons such that the interiors of the polygons do not intersect and the union of the polygons is equal to the interior of the original polygon P. A y-monotone polygon is a polygon whose vertices v1,…,vn can be divided into two chains v1,…,vk and vk,…,vn,v1, such that any horizontal line intersects either chain at most once. This algorithm does not guarantee a bound on the number of polygons produced with respect to the optimal number. |
Availability: 3.5.0 - requires SFCGAL >= 1.5.0.
Requires SFCGAL >= 1.5.0
This method needs SFCGAL backend.
Examples
 Original polygon |
 Y-Monotone Partition (same example As CG_ApproxConvexPartition, CG_GreeneApproxConvexPartition and CG_OptimalConvexPartition) |
SELECT ST_AsText(CG_YMonotonePartition('POLYGON((156 150,83 181,89 131,148 120,107 61,32 159,0 45,41 86,45 1,177 2,67 24,109 31,170 60,180 110,156 150))'::geometry));
GEOMETRYCOLLECTION(POLYGON((32 159,0 45,41 86,32 159)),POLYGON((107 61,32 159,41 86,45 1,177 2,67 24,109 31,170 60,107 61)),POLYGON((156 150,83 181,89 131,148 120,107 61,170 60,180 110,156 150)))