jvx.geom

Class PnPolygon

java.lang.Object

jvx.geom.PnPolygon

public class PnPolygon
extends java.lang.Object

Static methods that work on the geometry of polygons.

Author:

Eike Preuss

Version:

02.08.2006, 1.10 (mn) Cleaned code.
28.09.2004, 1.00 (ep) Created.

Constructor Summary

Constructors

Constructor and Description
PnPolygon()

Method Summary

Modifier and Type	Method and Description
static PdVector	computeCurvature(PgPolygon poly, PdVector curvature, boolean integrated) Computes the curvature of the given polygon.
static PdVector	computeCurvature(PgPolygon poly, PdVector curvature, double integrationRadius) Computes the curvature of the given polygon.
static PdVector[]	computeCurvatureVectors(PgPolygon poly, PdVector[] out) Computes the vertex-based curvature vectors for a polygon whose length is an approximation of the pointwise curvature via the tangens-formula: roughly like: curvature = length(edge)*tan(outerangle/2).
static void	computeEdgeLengths(PgPolygon poly, PdVector es) Computes the lengths of edges and stores them in the output array es.
static void	computeFrenetFrame(PgPolygon poly) Adds a Frenet frame as two vector fields to the polygon.
static PgFrame[]	computeFrenetFrame(PgPolygon poly, PgFrame[] vertframe) Computes the Frenet frame for a given polygon.
static void	computeParallelFrame(PgPolygon poly) Adds a parallel frame as two vector fields to the polygon.
static PgFrame[]	computeParallelFrame(PgPolygon poly, PgFrame[] vertframe) Computes a parallel moving frame for the given polygon with 'random' initial frame.
static void	identifyVertices(PgPolygon poly) Identifies successive vertices, whose distance is less than PuMath.EPS.
static void	identifyVertices(PgPolygon poly, double eps) Identifies successive vertices, whose distance is less than eps.
static void	reverse(PgPolygon polygon) Reverses the order of the vertices of a given polygon.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PnPolygon

public PnPolygon()

Method Detail

computeCurvature

public static PdVector computeCurvature(PgPolygon poly,
                                        PdVector curvature,
                                        boolean integrated)

Computes the curvature of the given polygon. It is the signed curvature if dim==2, otherwise it depends on correct vertex normals of the polygon.

Parameters:

poly - Polygon to compute the curvature of.

curvature - Output. May be null. Resized to numVertices if smaller.

integrated - If true, the integrated curvatures are calculated (length * k).

Returns:

Parameter curvature or a newly allocated vector if parameter is null.

Author:

Matthias Nieser

Version:

26.07.06, 1.00 created (mn)

computeCurvature

public static PdVector computeCurvature(PgPolygon poly,
                                        PdVector curvature,
                                        double integrationRadius)

Computes the curvature of the given polygon. It is the signed curvature if dim==2, otherwise it depends on correct vertex normals of the polygon. The curvatures are integrated values over an interval of given size around each vertex. Thus, the computed values are independent of the discretization of the polygon.

Parameters:

poly - Polygon to compute the curvature of.

curvature - Output. May be null. Resized to numVertices if smaller.

Returns:

Parameter curvature or a newly allocated vector if parameter is null.

Author:

Eike Preuss

computeCurvatureVectors

public static PdVector[] computeCurvatureVectors(PgPolygon poly,
                                                 PdVector[] out)

Computes the vertex-based curvature vectors for a polygon whose length is an approximation of the pointwise curvature via the tangens-formula: roughly like: curvature = length(edge)*tan(outerangle/2).

Parameters:

poly - Polygon.

out - Output, resized to numVertices if smaller. May be null.

Returns:

Reference to parameter out (or newly allocated array) which contains the vertex-based curvature vectors.

Author:

Eike Preuss

Version:

23.10.16, 2.50 revised (kp) Calculation simplified, doc added.
21.06.07, 2.00 revised (mn) Cleaned code and moved to PnPolygon.
1.00 created (ep)

computeEdgeLengths

public static void computeEdgeLengths(PgPolygon poly,
                                      PdVector es)

Computes the lengths of edges and stores them in the output array es.

Author:

Matthias Nieser

Version:

02.08.2006, 1.00 created (mn)

computeFrenetFrame

public static PgFrame[] computeFrenetFrame(PgPolygon poly,
                                           PgFrame[] vertframe)

Computes the Frenet frame for a given polygon.

Author:

Eike Preuss

Version:

08.02.2008 revised (kp) Method moved to dev.geom.PnPolygon from devKP.tebis.geom.PnFrenetFrame.

computeParallelFrame

public static PgFrame[] computeParallelFrame(PgPolygon poly,
                                             PgFrame[] vertframe)

Computes a parallel moving frame for the given polygon with 'random' initial frame. Edges may not be degenerated.

Parameters:

vertframe - output, resized to numVertices if smaller; may be null

Returns:

reference to vertframe parameter or newly created array

Author:

Eike Preuss

computeParallelFrame

public static void computeParallelFrame(PgPolygon poly)

Adds a parallel frame as two vector fields to the polygon.

Author:

Eike Preuss

computeFrenetFrame

public static void computeFrenetFrame(PgPolygon poly)

Adds a Frenet frame as two vector fields to the polygon.

Author:

Eike Preuss

identifyVertices

public static void identifyVertices(PgPolygon poly)

Identifies successive vertices, whose distance is less than PuMath.EPS. If the first and last vertex are identified, the polygon gets closed.

identifyVertices

public static void identifyVertices(PgPolygon poly,
                                    double eps)

Identifies successive vertices, whose distance is less than eps. If the first and last vertex are identified, the polygon gets closed.

reverse

public static void reverse(PgPolygon polygon)

Reverses the order of the vertices of a given polygon.