org.wamblee.gps.geometry.Plane Maven / Gradle / Ivy
/*
* Copyright 2006 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.wamblee.gps.geometry;
import org.wamblee.general.Pair;
/**
* Represents a plane. Usually used to represent a tangent plane to the earth surface to
* locally approximate the earth as flat.
*
* @author Erik Brakkee
*/
public class Plane {
private static final double EPS = 1e-4;
private Coordinates _point;
private Coordinates _normal;
private Coordinates _north;
private Coordinates _east;
/**
* Constructs a plane.
* @param aPoint Point on the plane.
* @param aNormal Normal, not necessarily normalized.
*/
public Plane(Point aPoint, Point aNormal) {
_point = aPoint.getReferenceCoordinates();
_normal = aNormal.getReferenceCoordinates().normalize();
Coordinates north = new Coordinates(0.0, 0.0, 1.0);
_north = north.subtract(_normal.scale(north.innerProduct(_normal))).normalize();
_east = _north.outerProduct(_normal);
if ( _normal.innerProduct(_north) > EPS ) {
throw new IllegalArgumentException("North access is not within the plane");
}
}
/**
* Projects a point onto the plane.
* @param aPoint Point to project.
* @return Projected point.
*/
private Coordinates project(Point aPoint) {
Coordinates ref = aPoint.getReferenceCoordinates();
double lambda = _normal.innerProduct(
_point.subtract(ref));
return ref.add(_normal.scale(lambda));
}
/**
* Returns normalized coordinates within the plane of the projection of a point.
*/
public Pair normalizedProjection(Point aPoint) {
Coordinates projection = project(aPoint);
Coordinates delta = projection.subtract(_point);
double x1 = delta.innerProduct(_north);
double x2 = delta.innerProduct(_east);
return new Pair(x1, x2);
}
}