/*
* The JTS Topology Suite is a collection of Java classes that
* implement the fundamental operations required to validate a given
* geo-spatial data set to a known topological specification.
*
* Copyright (C) 2001 Vivid Solutions
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* For more information, contact:
*
* Vivid Solutions
* Suite #1A
* 2328 Government Street
* Victoria BC V8T 5G5
* Canada
*
* (250)385-6040
* www.vividsolutions.com
*/
package com.vividsolutions.jts.algorithm;
import com.vividsolutions.jts.geom.Coordinate;
/**
* Functions for performing vector mathematics.
*
* @author Martin Davis
* @version 1.0
*/
public class VectorMath
{
/**
* Computes the normal vector to the triangle p0-p1-p2. In order to compute the normal each
* triangle coordinate must have a Z value. If this is not the case, the returned Coordinate
* will have NaN values. The returned vector has unit length.
*
* @param p0
* @param p1
* @param p2
* @return
*/
public static Coordinate normalToTriangle(Coordinate p0, Coordinate p1, Coordinate p2) {
Coordinate v1 = new Coordinate(p1.x - p0.x, p1.y - p0.y, p1.z - p0.z);
Coordinate v2 = new Coordinate(p2.x - p0.x, p2.y - p0.y, p2.z - p0.z);
Coordinate cp = crossProduct(v1, v2);
normalize(cp);
return cp;
}
public static void normalize(Coordinate v) {
double absVal = Math.sqrt(v.x * v.x + v.y * v.y + v.z * v.z);
v.x /= absVal;
v.y /= absVal;
v.z /= absVal;
}
public static Coordinate crossProduct(Coordinate v1, Coordinate v2) {
double x = det(v1.y, v1.z, v2.y, v2.z);
double y = -det(v1.x, v1.z, v2.x, v2.z);
double z = det(v1.x, v1.y, v2.x, v2.y);
return new Coordinate(x, y, z);
}
public static double dotProduct(Coordinate v1, Coordinate v2) {
return v1.x * v2.x + v1.y * v2.y + v1.z * v2.z;
}
public static double det(double a1, double a2, double b1, double b2) {
return (a1 * b2) - (a2 * b1);
}
}