Class ConformingDelaunayTriangulator
- java.lang.Object
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- org.locationtech.jts.triangulate.ConformingDelaunayTriangulator
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public class ConformingDelaunayTriangulator extends java.lang.Object
Computes a Conforming Delaunay Triangulation over a set of sites and a set of linear constraints.A conforming Delaunay triangulation is a true Delaunay triangulation. In it each constraint segment is present as a union of one or more triangulation edges. Constraint segments may be subdivided into two or more triangulation edges by the insertion of additional sites. The additional sites are called Steiner points, and are necessary to allow the segments to be faithfully reflected in the triangulation while maintaining the Delaunay property. Another way of stating this is that in a conforming Delaunay triangulation every constraint segment will be the union of a subset of the triangulation edges (up to tolerance).
A Conforming Delaunay triangulation is distinct from a Constrained Delaunay triangulation. A Constrained Delaunay triangulation is not necessarily fully Delaunay, and it contains the constraint segments exactly as edges of the triangulation.
A typical usage pattern for the triangulator is:
ConformingDelaunayTriangulator cdt = new ConformingDelaunayTriangulator(sites, tolerance); // optional cdt.setSplitPointFinder(splitPointFinder); cdt.setVertexFactory(vertexFactory); cdt.setConstraints(segments, new ArrayList(vertexMap.values())); cdt.formInitialDelaunay(); cdt.enforceConstraints(); subdiv = cdt.getSubdivision();
- Author:
- David Skea, Martin Davis
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Constructor Summary
Constructors Constructor Description ConformingDelaunayTriangulator(java.util.Collection initialVertices, double tolerance)
Creates a Conforming Delaunay Triangulation based on the given unconstrained initial vertices.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
enforceConstraints()
Enforces the supplied constraints into the triangulation.void
formInitialDelaunay()
Computes the Delaunay triangulation of the initial sites.java.util.Collection
getConstraintSegments()
Gets theSegment
s which represent the constraints.Geometry
getConvexHull()
Gets the convex hull of all the sites in the triangulation, including constraint vertices.java.util.List
getInitialVertices()
Gets the sites (vertices) used to initialize the triangulation.KdTree
getKDT()
Gets theKdTree
which contains the vertices of the triangulation.QuadEdgeSubdivision
getSubdivision()
Gets theQuadEdgeSubdivision
which represents the triangulation.double
getTolerance()
Gets the tolerance value used to construct the triangulation.ConstraintVertexFactory
getVertexFactory()
Gets the ConstraintVertexFactory used to create new constraint vertices at split points.void
insertSite(Coordinate p)
Inserts a site into the triangulation, maintaining the conformal Delaunay property.void
setConstraints(java.util.List segments, java.util.List segVertices)
Sets the constraints to be conformed to by the computed triangulation.void
setSplitPointFinder(ConstraintSplitPointFinder splitFinder)
Sets theConstraintSplitPointFinder
to be used during constraint enforcement.void
setVertexFactory(ConstraintVertexFactory vertexFactory)
Sets a customConstraintVertexFactory
to be used to allow vertices carrying extra information to be created.
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Constructor Detail
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ConformingDelaunayTriangulator
public ConformingDelaunayTriangulator(java.util.Collection initialVertices, double tolerance)
Creates a Conforming Delaunay Triangulation based on the given unconstrained initial vertices. The initial vertex set should not contain any vertices which appear in the constraint set.- Parameters:
initialVertices
- a collection ofConstraintVertex
tolerance
- the distance tolerance below which points are considered identical
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Method Detail
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setConstraints
public void setConstraints(java.util.List segments, java.util.List segVertices)
Sets the constraints to be conformed to by the computed triangulation. The constraints must not contain duplicate segments (up to orientation). The unique set of vertices (asConstraintVertex
es) forming the constraints must also be supplied. Supplying it explicitly allows the ConstraintVertexes to be initialized appropriately (e.g. with external data), and avoids re-computing the unique set if it is already available.- Parameters:
segments
- a list of the constraintSegment
ssegVertices
- the set of uniqueConstraintVertex
es referenced by the segments
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setSplitPointFinder
public void setSplitPointFinder(ConstraintSplitPointFinder splitFinder)
Sets theConstraintSplitPointFinder
to be used during constraint enforcement. Different splitting strategies may be appropriate for special situations.- Parameters:
splitFinder
- the ConstraintSplitPointFinder to be used
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getTolerance
public double getTolerance()
Gets the tolerance value used to construct the triangulation.- Returns:
- a tolerance value
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getVertexFactory
public ConstraintVertexFactory getVertexFactory()
Gets the ConstraintVertexFactory used to create new constraint vertices at split points.- Returns:
- a new constraint vertex
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setVertexFactory
public void setVertexFactory(ConstraintVertexFactory vertexFactory)
Sets a customConstraintVertexFactory
to be used to allow vertices carrying extra information to be created.- Parameters:
vertexFactory
- the ConstraintVertexFactory to be used
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getSubdivision
public QuadEdgeSubdivision getSubdivision()
Gets theQuadEdgeSubdivision
which represents the triangulation.- Returns:
- a subdivision
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getKDT
public KdTree getKDT()
Gets theKdTree
which contains the vertices of the triangulation.- Returns:
- a KdTree
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getInitialVertices
public java.util.List getInitialVertices()
Gets the sites (vertices) used to initialize the triangulation.- Returns:
- a List of Vertex
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getConstraintSegments
public java.util.Collection getConstraintSegments()
Gets theSegment
s which represent the constraints.- Returns:
- a collection of Segments
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getConvexHull
public Geometry getConvexHull()
Gets the convex hull of all the sites in the triangulation, including constraint vertices. Only valid after the constraints have been enforced.- Returns:
- the convex hull of the sites
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insertSite
public void insertSite(Coordinate p)
Inserts a site into the triangulation, maintaining the conformal Delaunay property. This can be used to further refine the triangulation if required (e.g. to approximate the medial axis of the constraints, or to improve the grading of the triangulation).- Parameters:
p
- the location of the site to insert
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formInitialDelaunay
public void formInitialDelaunay()
Computes the Delaunay triangulation of the initial sites.
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enforceConstraints
public void enforceConstraints()
Enforces the supplied constraints into the triangulation.- Throws:
ConstraintEnforcementException
- if the constraints cannot be enforced
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