AlgoKimberling.java example

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geogebra-master
package org.geogebra.common.kernel.barycentric;

import org.geogebra.common.kernel.Construction;
import org.geogebra.common.kernel.Kernel;
import org.geogebra.common.kernel.algos.AlgoElement;
import org.geogebra.common.kernel.commands.Commands;
import org.geogebra.common.kernel.geos.GeoElement;
import org.geogebra.common.kernel.geos.GeoNumberValue;
import org.geogebra.common.kernel.geos.GeoPoint;
import org.geogebra.common.kernel.kernelND.GeoPointND;
import org.geogebra.common.main.AlgoKimberlingWeightsParams;
import org.geogebra.common.util.MyMath;

/**
 * @author Zbynek Konecny, credit goes to Jason Cantarella of the Univerity of
 *         Georgia for creating a perl script which was used to create this
 *         class.
 * @version 30-09-2011
 * 
 *          This class calculates n-th Kimberling center of a triangle.
 * 
 */

public class AlgoKimberling extends AlgoElement {

	private GeoPointND A, B, C; // input
	private GeoPointND M; // output
	private GeoNumberValue n;

	/**
	 * Creates new algo for triangle center
	 * 
	 * @param cons
	 *            construction
	 * @param label
	 *            label
	 * @param A
	 *            first point
	 * @param B
	 *            second point
	 * @param C
	 *            third point
	 * @param n
	 *            index in ETC
	 */
	public AlgoKimberling(Construction cons, String label, GeoPointND A,
			GeoPointND B, GeoPointND C, GeoNumberValue n) {
		super(cons);
		kernel.getApplication().getAlgoKimberlingWeights();
		this.A = A;
		this.B = B;
		this.C = C;
		this.n = n;
		int dim = MyMath.max(A.getDimension(), B.getDimension(),
				C.getDimension());
		M = kernel.getGeoFactory().newPoint(dim, cons);
		setInputOutput();
		compute();
		M.setLabel(label);
	}

	@Override
	public Commands getClassName() {
		return Commands.TriangleCenter;
	}

	// for AlgoElement
	@Override
	protected void setInputOutput() {
		input = new GeoElement[4];
		input[0] = A.toGeoElement();
		input[1] = B.toGeoElement();
		input[2] = C.toGeoElement();
		input[3] = n.toGeoElement();

		setOutputLength(1);
		setOutput(0, M.toGeoElement());
		setDependencies(); // done by AlgoElement
	}

	/**
	 * @return resulting point
	 */
	public GeoPointND getResult() {
		return M;
	}

	@Override
	public final void compute() {

		// Check if the points are aligned
		double c = A.distance(B);
		double b = C.distance(A);
		double a = B.distance(C);
		double m = Math.min(Math.min(a, b), c);
		a = a / m;
		b = b / m;
		c = c / m;
		int k = (int) n.getDouble();

		if (kernel.getApplication().getAlgoKimberlingWeights() == null) {
			M.setUndefined();
		} else {
			double wA = kernel.getApplication().kimberlingWeight(
					new AlgoKimberlingWeightsParams(k, a, b, c));
			double wB = kernel.getApplication().kimberlingWeight(
					new AlgoKimberlingWeightsParams(k, b, c, a));
			double wC = kernel.getApplication().kimberlingWeight(
					new AlgoKimberlingWeightsParams(k, c, a, b));
			double w = wA + wB + wC;
			if (Double.isNaN(w) || Kernel.isZero(w)) {
				M.setUndefined();
			} else {
				GeoPoint.setBarycentric(A, B, C, wA, wB, wC, w, M);
			}
		}
	}
}