InhomogeneousPoint3D.java
/*
* Copyright (C) 2017 Alberto Irurueta Carro (alberto@irurueta.com)
*
* 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.irurueta.geometry;
import java.io.Serializable;
import java.util.Objects;
/**
* Subclass of Point3D defining an inhomogeneous 3D point.
* An inhomogeneous 3D point is defined by three coordinates: (x, y, z), where
* x, y and z are the horizontal, vertical and depth coordinates, respectively.
* Homogeneous 3D points can be transformed into inhomogeneous ones by
* normalizing x, y and z coordinates by the w factor as follows:
* Homogeneous 3D point (x,y,z,w) -< Inhomogeneous 3D point (x/w,y/w,z/w).
* Note that if and homogeneous 3D point is at infinity (w=0), its corresponding
* inhomogeneous point will be at infinity by setting (x=inf,y=inf,z=inf).
* Because of this, and because of machine precision, usually Homogeneous points
* are better suited when working at far distances or for numerical purposes,
* and their inhomogeneous counterparts are better suited when computing
* Euclidean distances, etc.
*/
public class InhomogeneousPoint3D extends Point3D implements Serializable {
/**
* Defines the X coordinate of an inhomogeneous 2D point.
*/
private double x;
/**
* Defines the Y coordinate of an inhomogeneous 2D point.
*/
private double y;
/**
* Defines the Z coordinate of an inhomogeneous 2D point.
*/
private double z;
/**
* Empty constructor.
*/
public InhomogeneousPoint3D() {
super();
x = y = z = 0.0;
}
/**
* Constructor of this class. This constructor sets a new inhomogeneous v
* array containing the coordinates X, Y and Z of the given point.
*
* @param v Array of length 3 containing the 3D coordinates of an
* inhomogeneous point.
* @throws IllegalArgumentException Raised when the size of the array is not
* 2.
*/
public InhomogeneousPoint3D(final double[] v) {
super();
setCoordinates(v);
}
/**
* Constructor of this class. This constructor sets a new inhomogeneous 3D
* point using the coordinates x, y and z of the given point.
*
* @param x X coordinate of the given 3D point.
* @param y Y coordinate of the given 3D point.
* @param z Z coordinate of the given 3D point.
*/
public InhomogeneousPoint3D(final double x, final double y, final double z) {
this.x = x;
this.y = y;
this.z = z;
}
/**
* This constructor sets a new inhomogeneous 3D point using as
* initialization provided Point3D instance.
*
* @param point Point to initialize new instance to.
*/
public InhomogeneousPoint3D(final Point3D point) {
setCoordinates(point);
}
/**
* Returns the X coordinate of the given homogeneous 3D point instance.
*
* @return X coordinate.
*/
public double getX() {
return x;
}
/**
* Sets the X coordinate of this homogeneous point.
*
* @param x X coordinate.
*/
public void setX(final double x) {
this.x = x;
}
/**
* Returns the Y coordinate of the given homogeneous 3D point instance.
*
* @return Y coordinate.
*/
public double getY() {
return y;
}
/**
* Sets the Y coordinate of this homogeneous point.
*
* @param y Y coordinate.
*/
public void setY(final double y) {
this.y = y;
}
/**
* Returns the Z coordinate of the given homogeneous 3D point instance.
*
* @return Z coordinate.
*/
public double getZ() {
return z;
}
/**
* Sets the Z coordinate of this homogeneous point.
*
* @param z Z coordinate.
*/
public void setZ(final double z) {
this.z = z;
}
/**
* Sets the coordinates of this inhomogeneous 3D point by using provided X,
* Y and Z coordinates.
*
* @param x X coordinate.
* @param y Y coordinate.
* @param z Z coordinate.
*/
public void setCoordinates(final double x, final double y, final double z) {
this.x = x;
this.y = y;
this.z = z;
}
/**
* Sets the coordinates of a 3D point using an array containing its
* coordinates.
*
* @param v Array containing the coordinates of the point.
* @throws IllegalArgumentException Raised if provided array does not have a
* valid size.
*/
@Override
public final void setCoordinates(final double[] v) {
if (v.length != POINT3D_INHOMOGENEOUS_COORDINATES_LENGTH) {
throw new IllegalArgumentException();
} else {
x = v[0];
y = v[1];
z = v[2];
}
}
/**
* Sets coordinates of this instance using the coordinates of provided 3D
* point.
*
* @param point Input point.
*/
@Override
public final void setCoordinates(final Point3D point) {
switch (point.getType()) {
case INHOMOGENEOUS_COORDINATES:
final var inhomPoint = (InhomogeneousPoint3D) point;
x = inhomPoint.getX();
y = inhomPoint.getY();
z = inhomPoint.getZ();
break;
case HOMOGENEOUS_COORDINATES:
default:
final var homPoint = (HomogeneousPoint3D) point;
x = homPoint.getInhomX();
y = homPoint.getInhomY();
z = homPoint.getInhomZ();
break;
}
}
/**
* Returns X homogeneous coordinate of this 3D point.
*
* @return X homogeneous coordinate.
*/
@Override
public double getHomX() {
return getX();
}
/**
* Returns Y homogeneous coordinate of this 3D point.
*
* @return Y homogeneous coordinate.
*/
@Override
public double getHomY() {
return getY();
}
/**
* Returns Z homogeneous coordinate of this 3D point.
*
* @return Z homogeneous coordinate.
*/
@Override
public double getHomZ() {
return getZ();
}
/**
* Returns W homogeneous coordinate of this 3D point.
*
* @return W homogeneous coordinate.
*/
@Override
public double getHomW() {
return 1.0;
}
/**
* Sets coordinates of this 3D point instance using provided homogeneous
* coordinates.
*
* @param homX x homogeneous coordinate.
* @param homY y homogeneous coordinate.
* @param homZ z homogeneous coordinate.
* @param homW w homogeneous coordinate.
*/
@Override
public void setHomogeneousCoordinates(final double homX, final double homY, final double homZ, final double homW) {
x = homX / homW;
y = homY / homW;
z = homZ / homW;
}
/**
* Returns X inhomogeneous coordinate of this 3D point.
*
* @return X inhomogeneous coordinate.
*/
@Override
public double getInhomX() {
return getX();
}
/**
* Sets X inhomogeneous coordinate of this 3D point.
*
* @param inhomX inhomogeneous coordinate.
*/
@Override
public void setInhomX(final double inhomX) {
x = inhomX;
}
/**
* Returns Y inhomogeneous coordinate of this 3D point.
*
* @return Y inhomogeneous coordinate.
*/
@Override
public double getInhomY() {
return getY();
}
/**
* Sets Y inhomogeneous coordinate of this 3D point.
*
* @param inhomY Y inhomogeneous coordinate.
*/
@Override
public void setInhomY(final double inhomY) {
y = inhomY;
}
/**
* Returns Z inhomogeneous coordinate of this 3D point.
*
* @return Z inhomogeneous coordinate.
*/
@Override
public double getInhomZ() {
return getZ();
}
/**
* Sets Z inhomogeneous coordinate of this 3D point.
*
* @param inhomZ Z inhomogeneous coordinate.
*/
@Override
public void setInhomZ(final double inhomZ) {
z = inhomZ;
}
/**
* Sets coordinates of this 3D point instance using provided inhomogeneous
* coordinates.
*
* @param inhomX x inhomogeneous coordinate.
* @param inhomY y inhomogeneous coordinate.
* @param inhomZ z inhomogeneous coordinate.
*/
@Override
public void setInhomogeneousCoordinates(final double inhomX, final double inhomY, final double inhomZ) {
setCoordinates(inhomX, inhomY, inhomZ);
}
/**
* Checks if provided object equals current 2D point.
*
* @param obj Object to compare.
* @return True if both objects are considered to be equal, false otherwise.
*/
@Override
public boolean equals(final Object obj) {
if (!(obj instanceof Point3D point)) {
return false;
}
if (obj == this) {
return true;
}
return equals(point);
}
/**
* Returns hash code value.
*
* @return Hash code value.
*/
@Override
public int hashCode() {
return Objects.hash(x, y, z, 1.0);
}
/**
* Checks if the homogeneous 3D point described by this instance equals the
* input Point3D (using a comparison threshold).
*
* @param point Point that will be compared to.
* @param threshold threshold grade of tolerance to determine whether the
* points are equal or not. It is used because due to machine precision, the
* values might not be exactly equal (if not provided
* DEFAULT_COMPARISON_THRESHOLD is used).
* @return True if current point and input point are the same, false
* otherwise.
* @throws IllegalArgumentException Raised if threshold is negative.
*/
@Override
public boolean equals(final Point3D point, final double threshold) {
if (point.getType() == CoordinatesType.INHOMOGENEOUS_COORDINATES) {
return equals((InhomogeneousPoint3D) point, threshold);
} else {
return equals((HomogeneousPoint3D) point, threshold);
}
}
/**
* Checks if the homogeneous 3D point described by this instance equals the
* input HomogeneousPoint3D (using a comparison threshold).
*
* @param point Point that will be compared to.
* @param threshold threshold grade of tolerance to determine whether the
* points are equal or not. It is used because due to machine precision, the
* values might not be exactly equal (if not provided
* DEFAULT_COMPARISON_THRESHOLD is used).
* @return True if current point and input point are the same, false
* otherwise.
* @throws IllegalArgumentException Raised if threshold is negative.
*/
public boolean equals(final HomogeneousPoint3D point, final double threshold) {
if (threshold < MIN_THRESHOLD) {
throw new IllegalArgumentException();
}
final var dX = Math.abs((point.getX() / point.getW()) - x) <= threshold;
final var dY = Math.abs((point.getY() / point.getW()) - y) <= threshold;
final var dZ = Math.abs((point.getZ() / point.getW()) - z) <= threshold;
return (dX && dY && dZ);
}
/**
* Checks if the homogeneous 3D point described by this instance equals the
* input HomogeneousPoint3D (using a comparison threshold).
*
* @param point Point that will be compared to.
* @return True if current point and input point are the same, false
* otherwise
*/
public boolean equals(final HomogeneousPoint3D point) {
return equals(point, DEFAULT_COMPARISON_THRESHOLD);
}
/**
* Checks if the homogeneous 3D point described by this instance equals the
* input InhomogeneousPoint3D (using a comparison threshold).
*
* @param point Point that will be compared to.
* @param threshold threshold grade of tolerance to determine whether the
* points are equal or not. It is used because due to machine precision, the
* values might not be exactly equal (if not provided
* DEFAULT_COMPARISON_THRESHOLD is used).
* @return True if current point and input point are the same, false
* otherwise.
* @throws IllegalArgumentException Raised if threshold is negative.
*/
public boolean equals(final InhomogeneousPoint3D point, double threshold) {
if (threshold < MIN_THRESHOLD) {
throw new IllegalArgumentException();
}
final var dX = Math.abs(point.getX() - x) <= threshold;
final var dY = Math.abs(point.getY() - y) <= threshold;
final var dZ = Math.abs(point.getZ() - z) <= threshold;
return (dX && dY && dZ);
}
/**
* Checks if the homogeneous 3D point described by this instance equals the
* input InhomogeneousPoint3D (using a comparison threshold).
*
* @param point Point that will be compared to.
* @return True if current point and input point are the same, false
* otherwise.
*/
public boolean equals(final InhomogeneousPoint3D point) {
return equals(point, DEFAULT_COMPARISON_THRESHOLD);
}
/**
* Checks whether this Point3D is at infinity or not.
*
* @return True if the point is at infinity. False otherwise.
*/
@Override
public boolean isAtInfinity() {
return (Double.isInfinite(x) || Double.isNaN(x) || Double.isInfinite(y) || Double.isNaN(y)
|| Double.isInfinite(z) || Double.isNaN(z));
}
/**
* Returns the type of coordinates used to represent a Point3D.
*
* @return Type of coordinates of this 3D point.
*/
@Override
public CoordinatesType getType() {
return CoordinatesType.INHOMOGENEOUS_COORDINATES;
}
/**
* Converts this instance into an homogeneous 3D point and returns the
* result as a new homogeneous 3D point instance.
*
* @return Converts and returns this point as an homogeneous 3D point.
*/
public HomogeneousPoint3D toHomogeneous() {
return new HomogeneousPoint3D(x, y, z, 1.0);
}
/**
* Returns an array containing the coordinates of this Point3D.
*
* @return Array containing coordinates of this Point3D.
*/
@Override
public double[] asArray() {
final var out = new double[POINT3D_INHOMOGENEOUS_COORDINATES_LENGTH];
asArray(out);
return out;
}
/**
* Uses provided array to store the coordinates of this InhomogeneousPoint3D
*
* @param array Array where coordinates will be stored.
* @throws IllegalArgumentException Raised if length of array is not 2.
*/
@Override
public void asArray(double[] array) {
if (array.length != POINT3D_INHOMOGENEOUS_COORDINATES_LENGTH)
throw new IllegalArgumentException();
array[0] = x;
array[1] = y;
array[2] = z;
}
}