Point2d.java
package org.djutils.draw.point;
import java.awt.geom.Point2D;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import org.djutils.draw.DrawRuntimeException;
import org.djutils.draw.Drawable2d;
import org.djutils.draw.Space2d;
import org.djutils.draw.bounds.Bounds2d;
import org.djutils.draw.line.Ray2d;
import org.djutils.exceptions.Throw;
/**
* A Point2d is an immutable Point with an x and y coordinate, stored with double precision. It differs from many Point
* implementations by being immutable.
* <p>
* Copyright (c) 2020-2021 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
* BSD-style license. See <a href="https://djutils.org/docs/current/djutils/licenses.html">DJUTILS License</a>.
* </p>
* @author <a href="https://www.tudelft.nl/averbraeck">Alexander Verbraeck</a>
* @author <a href="https://www.tudelft.nl/pknoppers">Peter Knoppers</a>
*/
public class Point2d implements Drawable2d, Point<Point2d, Space2d>
{
/** */
private static final long serialVersionUID = 20201201L;
/** The x-coordinate. */
@SuppressWarnings("checkstyle:visibilitymodifier")
public final double x;
/** The y-coordinate. */
@SuppressWarnings("checkstyle:visibilitymodifier")
public final double y;
/**
* Create a new Point with just an x and y coordinate, stored with double precision.
* @param x double; the x coordinate
* @param y double; the y coordinate
* @throws IllegalArgumentException when x or y is NaN
*/
public Point2d(final double x, final double y) throws IllegalArgumentException
{
Throw.when(Double.isNaN(x) || Double.isNaN(y), IllegalArgumentException.class, "Coordinate must be a number (not NaN)");
this.x = x;
this.y = y;
}
/**
* Create a new Point with just an x and y coordinate, stored with double precision.
* @param xy double[]; the x and y coordinate
* @throws NullPointerException when xy is null
* @throws IllegalArgumentException when the dimension of xy is not 2, or a coordinate is NaN
*/
public Point2d(final double[] xy) throws NullPointerException, IllegalArgumentException
{
this(checkLengthIsTwo(Throw.whenNull(xy, "xy-point cannot be null"))[0], xy[1]);
}
/**
* Create an immutable point with just two values, x and y, stored with double precision from an AWT Point2D.
* @param point Point2D; an AWT Point2D
* @throws NullPointerException when point is null
* @throws IllegalArgumentException when point has a NaN coordinate
*/
public Point2d(final Point2D point) throws NullPointerException, IllegalArgumentException
{
Throw.whenNull(point, "point cannot be null");
Throw.when(Double.isNaN(point.getX()) || Double.isNaN(point.getY()), IllegalArgumentException.class,
"Coordinate must be a number (not NaN)");
this.x = point.getX();
this.y = point.getY();
}
/**
* Throw an IllegalArgumentException if the length of the provided array is not two.
* @param xy double[]; the provided array
* @return double[]; the provided array
* @throws IllegalArgumentException when length of xy is not two
*/
private static double[] checkLengthIsTwo(final double[] xy) throws IllegalArgumentException
{
Throw.when(xy.length != 2, IllegalArgumentException.class, "Length of xy-array must be 2");
return xy;
}
/** {@inheritDoc} */
@Override
public final double getX()
{
return this.x;
}
/** {@inheritDoc} */
@Override
public final double getY()
{
return this.y;
}
/** {@inheritDoc} */
@Override
public double distance(final Point2d otherPoint)
{
Throw.whenNull(otherPoint, "point cannot be null");
return Math.hypot(otherPoint.x - this.x, otherPoint.y - this.y);
}
/** {@inheritDoc} */
@Override
public double distanceSquared(final Point2d otherPoint) throws NullPointerException
{
Throw.whenNull(otherPoint, "point cannot be null");
double dx = getX() - otherPoint.x;
double dy = getY() - otherPoint.y;
return dx * dx + dy * dy;
}
/** {@inheritDoc} */
@Override
public int size()
{
return 1;
}
/** {@inheritDoc} */
@Override
public Iterator<? extends Point2d> getPoints()
{
return Arrays.stream(new Point2d[] {this}).iterator();
}
/**
* Return a new Point with a translation by the provided dx and dy.
* @param dx double; the horizontal translation
* @param dy double; the vertical translation
* @return P; a new point with the translated coordinates
* @throws IllegalArgumentException when dx, or dy is NaN
*/
public Point2d translate(final double dx, final double dy)
{
Throw.when(Double.isNaN(dx) || Double.isNaN(dy), IllegalArgumentException.class, "translation may not be NaN");
return new Point2d(getX() + dx, getY() + dy);
}
/**
* Return a new Point3d with a translation by the provided delta-x, delta-y and deltaZ.
* @param dx double; the x translation
* @param dy double; the y translation
* @param dz double; the z translation
* @return Point2d; a new point with the translated coordinates
* @throws IllegalArgumentException when dx, dy, or dz is NaN
*/
public Point3d translate(final double dx, final double dy, final double dz)
{
Throw.when(Double.isNaN(dx) || Double.isNaN(dy) || Double.isNaN(dz), IllegalArgumentException.class,
"translation may not be NaN");
return new Point3d(getX() + dx, getY() + dy, dz);
}
/** {@inheritDoc} */
@Override
public Point2d scale(final double factor)
{
Throw.when(Double.isNaN(factor), IllegalArgumentException.class, "factor must be a number (not NaN)");
return new Point2d(getX() * factor, getY() * factor);
}
/** {@inheritDoc} */
@Override
public Point2d neg()
{
return scale(-1.0);
}
/** {@inheritDoc} */
@Override
public Point2d abs()
{
return new Point2d(Math.abs(getX()), Math.abs(getY()));
}
/** {@inheritDoc} */
@Override
public Point2d normalize() throws DrawRuntimeException
{
double length = Math.sqrt(getX() * getX() + getY() * getY());
Throw.when(length == 0.0, DrawRuntimeException.class, "cannot normalize (0.0, 0.0)");
return this.scale(1.0 / length);
}
/** {@inheritDoc} */
@Override
public Point2d interpolate(final Point2d point, final double fraction)
{
Throw.whenNull(point, "point cannot be null");
Throw.when(Double.isNaN(fraction), IllegalArgumentException.class, "fraction must be a number (not NaN)");
return new Point2d((1.0 - fraction) * getX() + fraction * point.x, (1.0 - fraction) * getY() + fraction * point.y);
}
/** {@inheritDoc} */
@Override
public boolean epsilonEquals(final Point2d other, final double epsilon)
{
Throw.whenNull(other, "other point cannot be null");
if (Math.abs(getX() - other.x) > epsilon)
{
return false;
}
if (Math.abs(getY() - other.y) > epsilon)
{
return false;
}
return true;
}
/** {@inheritDoc} */
@Override
public Bounds2d getBounds()
{
return new Bounds2d(this);
}
/**
* Compute the 2D intersection of two lines. Both lines are defined by two points (that should be distinct).
* @param line1P1 Point2d; first point of line 1
* @param line1P2 Point2d; second point of line 1
* @param line2P1 Point2d; first point of line 2
* @param line2P2 Point2d; second point of line 2
* @return Point2d; the intersection of the two lines, or null if the lines are (almost) parallel
*/
public static Point2d intersectionOfLines(final Point2d line1P1, final Point2d line1P2, final Point2d line2P1,
final Point2d line2P2)
{
double l1p1x = line1P1.x;
double l1p1y = line1P1.y;
double l1p2x = line1P2.x - l1p1x;
double l1p2y = line1P2.y - l1p1y;
double l2p1x = line2P1.x - l1p1x;
double l2p1y = line2P1.y - l1p1y;
double l2p2x = line2P2.x - l1p1x;
double l2p2y = line2P2.y - l1p1y;
double denominator = (l2p2y - l2p1y) * l1p2x - (l2p2x - l2p1x) * l1p2y;
if (denominator == 0.0)
{
return null; // lines are parallel (they might even be on top of each other, but we don't check that)
}
double u = ((l2p2x - l2p1x) * (-l2p1y) - (l2p2y - l2p1y) * (-l2p1x)) / denominator;
return line1P1.interpolate(line1P2, u);
}
/**
* Compute the 2D intersection of two line segments. Both line segments are defined by two points (that should be distinct).
* @param line1P1 Point2d; first point of line segment 1
* @param line1P2 Point2d; second point of line segment 1
* @param line2P1 Point2d; first point of line segment 2
* @param line2P2 Point2d; second point of line segment 2
* @return Point2d; the intersection of the two line segments, or null if the lines are (almost) parallel, or do not
* intersect
*/
public static Point2d intersectionOfLineSegments(final Point2d line1P1, final Point2d line1P2, final Point2d line2P1,
final Point2d line2P2)
{
double l1p1x = line1P1.x;
double l1p1y = line1P1.y;
double l1p2x = line1P2.x - l1p1x;
double l1p2y = line1P2.y - l1p1y;
double l2p1x = line2P1.x - l1p1x;
double l2p1y = line2P1.y - l1p1y;
double l2p2x = line2P2.x - l1p1x;
double l2p2y = line2P2.y - l1p1y;
double denominator = (l2p2y - l2p1y) * l1p2x - (l2p2x - l2p1x) * l1p2y;
if (denominator == 0.0)
{
return null; // lines are parallel (they might even be on top of each other, but we don't check that)
}
double uA = ((l2p2x - l2p1x) * (-l2p1y) - (l2p2y - l2p1y) * (-l2p1x)) / denominator;
// System.out.println("uA is " + uA);
if ((uA < 0.0) || (uA > 1.0))
{
return null; // intersection outside line 1
}
double uB = (l1p2y * l2p1x - l1p2x * l2p1y) / denominator;
// System.out.println("uB is " + uB);
if (uB < 0.0 || uB > 1.0)
{
return null; // intersection outside line 2
}
return line1P1.interpolate(line1P2, uA);
// return new Point2d(line1P1.x + uA * l1p2x, line1P1.y + uA * l1p2y);
}
/** {@inheritDoc} */
@Override
public final Point2d closestPointOnSegment(final Point2d segmentPoint1, final Point2d segmentPoint2)
{
double dX = segmentPoint2.x - segmentPoint1.x;
double dY = segmentPoint2.y - segmentPoint1.y;
if (0 == dX && 0 == dY) // The points may be equal (unlike in Segment2d)
{
return segmentPoint1;
}
final double u = ((this.x - segmentPoint1.x) * dX + (this.y - segmentPoint1.y) * dY) / (dX * dX + dY * dY);
if (u < 0)
{
return segmentPoint1;
}
else if (u > 1)
{
return segmentPoint2;
}
else
{
return segmentPoint1.interpolate(segmentPoint2, u);
}
}
/** {@inheritDoc} */
@Override
public final Point2d closestPointOnLine(final Point2d linePoint1, final Point2d linePoint2) throws DrawRuntimeException
{
double dX = linePoint2.x - linePoint1.x;
double dY = linePoint2.y - linePoint1.y;
Throw.when(dX == 0 && dY == 0, DrawRuntimeException.class, "line points are at same location");
final double u = ((this.x - linePoint1.x) * dX + (this.y - linePoint1.y) * dY) / (dX * dX + dY * dY);
return linePoint1.interpolate(linePoint2, u);
}
/**
* Closest point on a ray.
* @param ray Ray2d; the ray
* @return Point2d; the point on the ray that is closest to this
*/
public final Point2d closestPointOnLine(final Ray2d ray)
{
double dX = Math.cos(ray.phi);
double dY = Math.sin(ray.phi);
final double u = ((this.x - ray.x) * dX + (this.y - ray.y) * dY) / (dX * dX + dY * dY);
return ray.interpolate(new Point2d(ray.x + dX, ray.y + dY), Math.max(0, u));
}
/**
* Return the zero, one or two intersections between two circles. The circles must be different. Derived from pseudo code by
* <a href="http://paulbourke.net/geometry/circlesphere/">Paul Bourke</a> and C implementation by
* <a href="http://paulbourke.net/geometry/circlesphere/tvoght.c">Tim Voght </a>.
* @param center1 Point2d; the center of circle 1
* @param radius1 double; the radius of circle 1
* @param center2 Point2d; the center of circle 2
* @param radius2 double; the radius of circle 2
* @return List<Point2d> a list of zero, one or two points
* @throws NullPointerException when center1 or center2 is null
* @throws DrawRuntimeException when the two circles are identical, or radius1 < 0 or radius2 < 0
*/
public static final List<Point2d> circleIntersections(final Point2d center1, final double radius1, final Point2d center2,
final double radius2) throws NullPointerException, DrawRuntimeException
{
Throw.whenNull(center1, "center1 may not be null");
Throw.whenNull(center2, "center2 may not be null");
Throw.when(radius1 < 0 || radius2 < 0, DrawRuntimeException.class, "radius may not be less than 0");
Throw.when(center1.equals(center2) && radius1 == radius2, DrawRuntimeException.class, "Circles must be different");
List<Point2d> result = new ArrayList<>();
// dX,dY is the vector from center1 to center2
double dX = center2.x - center1.x;
double dY = center2.y - center1.y;
double distance = Math.hypot(dX, dY);
if (distance > radius1 + radius2 || distance < Math.abs(radius1 - radius2))
{
return result;
}
double a = (radius1 * radius1 - radius2 * radius2 + distance * distance) / (2 * distance);
// x2,y2 is the point where the line through the circle intersections crosses the line through the circle centers
double x2 = center1.x + (dX * a / distance);
double y2 = center1.y + (dY * a / distance);
// h is distance from x2,y2 to each of the solutions
double h = Math.sqrt(radius1 * radius1 - a * a);
// rX, rY is vector from x2,y2 to the first solution
double rX = -dY * (h / distance);
double rY = dX * (h / distance);
result.add(new Point2d(x2 + rX, y2 + rY));
if (h > 0)
{
// Two distinct solutions; add the second one
result.add(new Point2d(x2 - rX, y2 - rY));
}
return result;
}
/**
* Return the direction to another Point2d.
* @param otherPoint Point2d; the other point
* @return double; the direction to the other point in Radians (towards infinite X is 0; towards infinite Y is π / 2;
* etc.). If the points are identical; this method returns NaN.
*/
public double directionTo(final Point2d otherPoint)
{
return Math.atan2(otherPoint.y - this.y, otherPoint.x - this.x);
}
/**
* Return the coordinates as an AWT Point2D.Double object.
* @return Point2D; the coordinates as an AWT Point2D.Double object
*/
public Point2D toPoint2D()
{
return new Point2D.Double(getX(), getY());
}
/** {@inheritDoc} */
@Override
public String toString(final int fractionDigits)
{
int digits = fractionDigits < 0 ? 0 : fractionDigits;
String format = String.format("(%%.%1$df,%%.%1$df)", digits);
return String.format(format, getX(), getY());
}
/** {@inheritDoc} */
@Override
public String toString()
{
return String.format("(%f,%f)", getX(), getY());
}
/** {@inheritDoc} */
@Override
public int hashCode()
{
final int prime = 31;
int result = 1;
long temp;
temp = Double.doubleToLongBits(this.x);
result = prime * result + (int) (temp ^ (temp >>> 32));
temp = Double.doubleToLongBits(this.y);
result = prime * result + (int) (temp ^ (temp >>> 32));
return result;
}
/** {@inheritDoc} */
@SuppressWarnings("checkstyle:needbraces")
@Override
public boolean equals(final Object obj)
{
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Point2d other = (Point2d) obj;
if (Double.doubleToLongBits(this.x) != Double.doubleToLongBits(other.x))
return false;
if (Double.doubleToLongBits(this.y) != Double.doubleToLongBits(other.y))
return false;
return true;
}
}