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/*
* Copyright 2005 Google Inc.
*
* 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 com.google.common.geometry;
/**
* R2Vector represents a vector in the two-dimensional space. It defines the
* basic geometrical operations for 2D vectors, e.g. cross product, addition,
* norm, comparison etc.
*
*/
public final strictfp class R2Vector {
final double x;
final double y;
public R2Vector() {
this(0, 0);
}
public R2Vector(double x, double y) {
this.x = x;
this.y = y;
}
public R2Vector(double[] coord) {
if (coord.length != 2) {
throw new IllegalStateException("Points must have exactly 2 coordinates");
}
x = coord[0];
y = coord[1];
}
public double get(int index) {
if (index > 1) {
throw new ArrayIndexOutOfBoundsException(index);
}
return index == 0 ? this.x : this.y;
}
public static R2Vector add(final R2Vector p1, final R2Vector p2) {
return new R2Vector(p1.x + p2.x, p1.y + p2.y);
}
public static R2Vector mul(final R2Vector p, double m) {
return new R2Vector(m * p.x, m * p.y);
}
public double norm2() {
return (x * x) + (y * y);
}
public static double dotProd(final R2Vector p1, final R2Vector p2) {
return (p1.x * p2.x) + (p1.y * p2.y);
}
public double dotProd(R2Vector that) {
return dotProd(this, that);
}
public double crossProd(final R2Vector that) {
return this.x * that.y - this.y * that.x;
}
public boolean lessThan(R2Vector vb) {
if (x < vb.x) {
return true;
}
if (vb.x < x) {
return false;
}
if (y < vb.y) {
return true;
}
return false;
}
@Override
public boolean equals(Object that) {
if (!(that instanceof R2Vector)) {
return false;
}
R2Vector thatPoint = (R2Vector) that;
return this.x == thatPoint.x && this.y == thatPoint.y;
}
/**
* Calcualates hashcode based on stored coordinates. Since we want +0.0 and
* -0.0 to be treated the same, we ignore the sign of the coordinates.
*/
@Override
public int hashCode() {
long value = 17;
value += 37 * value + Double.doubleToLongBits(Math.abs(x));
value += 37 * value + Double.doubleToLongBits(Math.abs(y));
return (int) (value ^ (value >>> 32));
}
@Override
public String toString() {
return "(" + x + ", " + y + ")";
}
}
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