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java.lang.Object org.apache.commons.math3.geometry.partitioning.AbstractRegion<Euclidean2D,Euclidean1D> org.apache.commons.math3.geometry.euclidean.twod.PolygonsSet
public class PolygonsSet
This class represents a 2D region: a set of polygons.
Nested Class Summary 

Nested classes/interfaces inherited from interface org.apache.commons.math3.geometry.partitioning.Region 

Region.Location 
Constructor Summary  

PolygonsSet()
Build a polygons set representing the whole real line. 

PolygonsSet(BSPTree<Euclidean2D> tree)
Build a polygons set from a BSP tree. 

PolygonsSet(Collection<SubHyperplane<Euclidean2D>> boundary)
Build a polygons set from a Boundary REPresentation (Brep). 

PolygonsSet(double xMin,
double xMax,
double yMin,
double yMax)
Build a parallellepipedic box. 

PolygonsSet(double hyperplaneThickness,
Vector2D... vertices)
Build a polygon from a simple list of vertices. 
Method Summary  

PolygonsSet 
buildNew(BSPTree<Euclidean2D> tree)
Build a region using the instance as a prototype. 
protected void 
computeGeometricalProperties()
Compute some geometrical properties. 
Vector2D[][] 
getVertices()
Get the vertices of the polygon. 
Methods inherited from class org.apache.commons.math3.geometry.partitioning.AbstractRegion 

applyTransform, checkPoint, checkPoint, contains, copySelf, getBarycenter, getBoundarySize, getSize, getTree, intersection, isEmpty, isEmpty, setBarycenter, setSize, side 
Methods inherited from class java.lang.Object 

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait 
Constructor Detail 

public PolygonsSet()
public PolygonsSet(BSPTree<Euclidean2D> tree)
The leaf nodes of the BSP tree must have a
Boolean
attribute representing the inside status of
the corresponding cell (true for inside cells, false for outside
cells). In order to avoid building too many small objects, it is
recommended to use the predefined constants
Boolean.TRUE
and Boolean.FALSE
tree
 inside/outside BSP tree representing the regionpublic PolygonsSet(Collection<SubHyperplane<Euclidean2D>> boundary)
The boundary is provided as a collection of subhyperplanes
. Each subhyperplane has the
interior part of the region on its minus side and the exterior on
its plus side.
The boundary elements can be in any order, and can form
several nonconnected sets (like for example polygons with holes
or a set of disjoint polyhedrons considered as a whole). In
fact, the elements do not even need to be connected together
(their topological connections are not used here). However, if the
boundary does not really separate an inside open from an outside
open (open having here its topological meaning), then subsequent
calls to the checkPoint
method will not be meaningful anymore.
If the boundary is empty, the region will represent the whole space.
boundary
 collection of boundary elements, as a
collection of SubHyperplane
objectspublic PolygonsSet(double xMin, double xMax, double yMin, double yMax)
xMin
 low bound along the x directionxMax
 high bound along the x directionyMin
 low bound along the y directionyMax
 high bound along the y directionpublic PolygonsSet(double hyperplaneThickness, Vector2D... vertices)
The boundary is provided as a list of points considering to represent the vertices of a simple loop. The interior part of the region is on the left side of this path and the exterior is on its right side.
This constructor does not handle polygons with a boundary forming several disconnected paths (such as polygons with holes).
For cases where this simple constructor applies, it is expected to
be numerically more robust than the general
constructor
using subhyperplanes
.
If the list is empty, the region will represent the whole space.
Polygons with thin pikes or dents are inherently difficult to handle because
they involve lines with almost opposite directions at some vertices. Polygons
whose vertices come from some physical measurement with noise are also
difficult because an edge that should be straight may be broken in lots of
different pieces with almost equal directions. In both cases, computing the
lines intersections is not numerically robust due to the almost 0 or almost
π angle. Such cases need to carefully adjust the hyperplaneThickness
parameter. A too small value would often lead to completely wrong polygons
with large area wrongly identified as inside or outside. Large values are
often much safer. As a rule of thumb, a value slightly below the size of the
most accurate detail needed is a good value for the hyperplaneThickness
parameter.
hyperplaneThickness
 tolerance below which points are considered to
belong to the hyperplane (which is therefore more a slab)vertices
 vertices of the simple loop boundaryMethod Detail 

public PolygonsSet buildNew(BSPTree<Euclidean2D> tree)
This method allow to create new instances without knowing exactly the type of the region. It is an application of the prototype design pattern.
The leaf nodes of the BSP tree must have a
Boolean
attribute representing the inside status of
the corresponding cell (true for inside cells, false for outside
cells). In order to avoid building too many small objects, it is
recommended to use the predefined constants
Boolean.TRUE
and Boolean.FALSE
. The
tree also must have either null internal nodes or
internal nodes representing the boundary as specified in the
getTree
method).
buildNew
in interface Region<Euclidean2D>
buildNew
in class AbstractRegion<Euclidean2D,Euclidean1D>
tree
 inside/outside BSP tree representing the new region
protected void computeGeometricalProperties()
The properties to compute are the barycenter and the size.
computeGeometricalProperties
in class AbstractRegion<Euclidean2D,Euclidean1D>
public Vector2D[][] getVertices()
The polygon boundary can be represented as an array of loops, each loop being itself an array of vertices.
In order to identify open loops which start and end by infinite edges, the open loops arrays start with a null point. In this case, the first non null point and the last point of the array do not represent real vertices, they are dummy points intended only to get the direction of the first and last edge. An open loop consisting of a single infinite line will therefore be represented by a three elements array with one null point followed by two dummy points. The open loops are always the first ones in the loops array.
If the polygon has no boundary at all, a zero length loop array will be returned.
All line segments in the various loops have the inside of the region on their left side and the outside on their right side when moving in the underlying line direction. This means that closed loops surrounding finite areas obey the direct trigonometric orientation.


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