org.tinfour.utils

Class BarycentricCoordinates

java.lang.Object

org.tinfour.utils.BarycentricCoordinates

public class BarycentricCoordinates
extends Object

Implements utilities for computing Barycentric Coordinates. The algorithm for computing coordinates is based on Hormann, Kai. (2005). "Barycentric Coordinates for Arbitrary Polygons in the Plane -- Technical Report IfI-05-05", Institute fur Informatik, Technische Universitat Clausthal.

Development Status: At this time, this class has not been thoroughly reviewed and has undergone only superficial testing.

Constructor Summary

Constructors

Constructor and Description
BarycentricCoordinates()

Method Summary

Modifier and Type	Method and Description
double	getBarycentricCoordinateDeviation() Gets the deviation of the computed equivalent of the input query (x,y) coordinates based on barycentric coordinates.
double[]	getBarycentricCoordinates(List<Vertex> polygon, double x, double y) Given a reference point inside a simple, but potentially non-convex polygon, creates an array of barycentric coordinates for the point.

Methods inherited from class java.lang.Object

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

Constructor Detail

BarycentricCoordinates

public BarycentricCoordinates()

Method Detail

getBarycentricCoordinates

public double[] getBarycentricCoordinates(List<Vertex> polygon,
                                          double x,
                                          double y)

Given a reference point inside a simple, but potentially non-convex polygon, creates an array of barycentric coordinates for the point. The coordinates are normalized, so that their sum is 1.0. This method populates the barycentric deviation member element which may be used as a figure of merit for evaluating the success of the coordinate computation. If the point is not inside the polygon or if the polygon is self-intersecting, the results are undefined and the method may return a null array or a meaningless result. If the point is on the perimeter of the polygon, this method will return a null array.

Parameters:

polygon - list of vertices defining a non-self-intersecting, potentially non-convex polygon.

x - the x coordinate of the reference point

y - the y coordinate of the reference point

Returns:

if successful, a valid array; otherwise a null.

getBarycentricCoordinateDeviation

public double getBarycentricCoordinateDeviation()

Gets the deviation of the computed equivalent of the input query (x,y) coordinates based on barycentric coordinates. While the computed equivalent should be an exact match for the query point, errors in implementation or numeric errors due to float-point precision limitations would result in a deviation. Thus, this method provides a diagnostic on the most recent computation. A large non-zero value indicates a potential implementation problem. A small non-zero value indicates an error due to numeric issues.

Returns:

a positive value, ideally zero but usually a small number slightly larger than that.