Lines.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.commons.geometry.euclidean.twod;
import java.text.MessageFormat;
import org.apache.commons.geometry.euclidean.oned.Interval;
import org.apache.commons.numbers.core.Precision;
/** Class containing factory methods for constructing {@link Line} and {@link LineSubset} instances.
*/
public final class Lines {
/** Utility class; no instantiation. */
private Lines() {
}
/** Create a line from two points lying on the line. The line points in the direction
* from {@code p1} to {@code p2}.
* @param p1 first point
* @param p2 second point
* @param precision precision context used to compare floating point values
* @return new line containing {@code p1} and {@code p2} and pointing in the direction
* from {@code p1} to {@code p2}
* @throws IllegalArgumentException If the vector between {@code p1} and {@code p2} has zero length,
* as evaluated by the given precision context
*/
public static Line fromPoints(final Vector2D p1, final Vector2D p2, final Precision.DoubleEquivalence precision) {
return fromPointAndDirection(p1, p1.vectorTo(p2), precision);
}
/** Create a line from a point and direction.
* @param pt point belonging to the line
* @param dir the direction of the line
* @param precision precision context used to compare floating point values
* @return new line containing {@code pt} and pointing in direction {@code dir}
* @throws IllegalArgumentException If {@code dir} has zero length, as evaluated by the
* given precision context
*/
public static Line fromPointAndDirection(final Vector2D pt, final Vector2D dir,
final Precision.DoubleEquivalence precision) {
if (dir.isZero(precision)) {
throw new IllegalArgumentException("Line direction cannot be zero");
}
final Vector2D.Unit normalizedDir = dir.normalize();
final double originOffset = normalizedDir.signedArea(pt);
return new Line(normalizedDir, originOffset, precision);
}
/** Create a line from a point lying on the line and an angle relative to the abscissa (x) axis. Note that the
* line does not need to intersect the x-axis; the given angle is simply relative to it.
* @param pt point belonging to the line
* @param angle angle of the line with respect to abscissa (x) axis, in radians
* @param precision precision context used to compare floating point values
* @return new line containing {@code pt} and forming the given angle with the
* abscissa (x) axis.
*/
public static Line fromPointAndAngle(final Vector2D pt, final double angle,
final Precision.DoubleEquivalence precision) {
final Vector2D.Unit dir = Vector2D.Unit.from(Math.cos(angle), Math.sin(angle));
return fromPointAndDirection(pt, dir, precision);
}
/** Construct a ray from a start point and a direction.
* @param startPoint ray start point
* @param direction ray direction
* @param precision precision context used for floating point comparisons
* @return a new ray instance with the given start point and direction
* @throws IllegalArgumentException If {@code direction} has zero length, as evaluated by the
* given precision context
* @see #fromPointAndDirection(Vector2D, Vector2D, Precision.DoubleEquivalence)
*/
public static Ray rayFromPointAndDirection(final Vector2D startPoint, final Vector2D direction,
final Precision.DoubleEquivalence precision) {
final Line line = Lines.fromPointAndDirection(startPoint, direction, precision);
return new Ray(line, startPoint);
}
/** Construct a ray starting at the given point and continuing to infinity in the direction
* of {@code line}. The given point is projected onto the line.
* @param line line for the ray
* @param startPoint start point for the ray
* @return a new ray instance starting at the given point and continuing in the direction of
* {@code line}
* @throws IllegalArgumentException if any coordinate in {@code startPoint} is NaN or infinite
*/
public static Ray rayFromPoint(final Line line, final Vector2D startPoint) {
if (!startPoint.isFinite()) {
throw new IllegalArgumentException("Invalid ray start point: " + startPoint);
}
return new Ray(line, line.project(startPoint));
}
/** Construct a ray starting at the given 1D location on {@code line} and continuing in the
* direction of the line to infinity.
* @param line line for the ray
* @param startLocation 1D location of the ray start point
* @return a new ray instance starting at the given 1D location and continuing to infinity
* along {@code line}
* @throws IllegalArgumentException if {@code startLocation} is NaN or infinite
*/
public static Ray rayFromLocation(final Line line, final double startLocation) {
if (!Double.isFinite(startLocation)) {
throw new IllegalArgumentException("Invalid ray start location: " + startLocation);
}
return new Ray(line, line.toSpace(startLocation));
}
/** Construct a reverse ray from an end point and a line direction.
* @param endPoint instance end point
* @param lineDirection line direction
* @param precision precision context used for floating point comparisons
* @return a new instance with the given end point and line direction
* @throws IllegalArgumentException If {@code lineDirection} has zero length, as evaluated by the
* given precision context
* @see #fromPointAndDirection(Vector2D, Vector2D, Precision.DoubleEquivalence)
*/
public static ReverseRay reverseRayFromPointAndDirection(final Vector2D endPoint, final Vector2D lineDirection,
final Precision.DoubleEquivalence precision) {
final Line line = Lines.fromPointAndDirection(endPoint, lineDirection, precision);
return new ReverseRay(line, endPoint);
}
/** Construct a reverse ray starting at infinity and continuing in the direction of {@code line}
* to the given end point. The point is projected onto the line.
* @param line line for the instance
* @param endPoint end point for the instance
* @return a new instance starting at infinity and continuing along the line to {@code endPoint}
* @throws IllegalArgumentException if any coordinate in {@code endPoint} is NaN or infinite
*/
public static ReverseRay reverseRayFromPoint(final Line line, final Vector2D endPoint) {
if (!endPoint.isFinite()) {
throw new IllegalArgumentException("Invalid reverse ray end point: " + endPoint);
}
return new ReverseRay(line, line.project(endPoint));
}
/** Construct a reverse ray starting at infinity and continuing in the direction of {@code line}
* to the given 1D end location.
* @param line line for the instance
* @param endLocation 1D location of the instance end point
* @return a new instance starting infinity and continuing in the direction of {@code line}
* to the given 1D end location
* @throws IllegalArgumentException if {@code endLocation} is NaN or infinite
*/
public static ReverseRay reverseRayFromLocation(final Line line, final double endLocation) {
if (!Double.isFinite(endLocation)) {
throw new IllegalArgumentException("Invalid reverse ray end location: " + endLocation);
}
return new ReverseRay(line, line.toSpace(endLocation));
}
/** Construct a new line segment from two points. A new line is created for the segment and points in the
* direction from {@code startPoint} to {@code endPoint}.
* @param startPoint segment start point
* @param endPoint segment end point
* @param precision precision context to use for floating point comparisons
* @return a new line segment instance with the given start and end points
* @throws IllegalArgumentException If the vector between {@code startPoint} and {@code endPoint} has zero length,
* as evaluated by the given precision context
*/
public static Segment segmentFromPoints(final Vector2D startPoint, final Vector2D endPoint,
final Precision.DoubleEquivalence precision) {
final Line line = Lines.fromPoints(startPoint, endPoint, precision);
// we know that the points lie on the line and are in increasing abscissa order
// since they were used to create the line
return new Segment(line, startPoint, endPoint);
}
/** Construct a new line segment from a line and a pair of points. The returned segment represents
* all points on the line between the projected locations of {@code a} and {@code b}. The points may
* be given in any order.
* @param line line forming the base of the segment
* @param a first point
* @param b second point
* @return a new line segment representing the points between the projected locations of {@code a}
* and {@code b} on the given line
* @throws IllegalArgumentException if either point contains NaN or infinite coordinate values
*/
public static Segment segmentFromPoints(final Line line, final Vector2D a, final Vector2D b) {
return segmentFromLocations(line, line.abscissa(a), line.abscissa(b));
}
/** Construct a new line segment from a pair of 1D locations on a line. The returned line
* segment consists of all points between the two locations, regardless of the order the
* arguments are given.
* @param line line forming the base of the segment
* @param a first 1D location on the line
* @param b second 1D location on the line
* @return a new line segment representing the points between {@code a} and {@code b} on
* the given line
* @throws IllegalArgumentException if either of the locations is NaN or infinite
*/
public static Segment segmentFromLocations(final Line line, final double a, final double b) {
if (Double.isFinite(a) && Double.isFinite(b)) {
final double min = Math.min(a, b);
final double max = Math.max(a, b);
return new Segment(line, line.toSpace(min), line.toSpace(max));
}
throw new IllegalArgumentException(
MessageFormat.format("Invalid line segment locations: {0}, {1}",
Double.toString(a), Double.toString(b)));
}
/** Create a {@link LineConvexSubset} spanning the entire line. In other words, the returned
* subset is infinite and contains all points on the given line.
* @param line the line to span
* @return a convex subset spanning the entire line
*/
public static LineConvexSubset span(final Line line) {
return new LineSpanningSubset(line);
}
/** Create a line subset from a line and a 1D interval on the line. The returned subset
* uses the precision context from the line and not any precision contexts referenced by the interval.
* @param line the line containing the subset
* @param interval 1D interval on the line
* @return a convex subset defined by the given line and interval
*/
public static LineConvexSubset subsetFromInterval(final Line line, final Interval interval) {
return subsetFromInterval(line, interval.getMin(), interval.getMax());
}
/** Create a line subset from a line and a 1D interval on the line. The double values may be given in any
* order and support the use of infinite values. For example, the call
* {@code Lines.subsetFromInterval(line, Double.POSITIVE_INFINITY, Double.NEGATIVE_INFINITY)} will return
* an instance representing the full span of the line.
* @param line the line containing the subset
* @param a first 1D location on the line
* @param b second 1D location on the line
* @return a line subset defined by the given line and interval
* @throws IllegalArgumentException if either double value is NaN or both are infinite with the same sign
* (eg, both positive infinity or both negative infinity)
*/
public static LineConvexSubset subsetFromInterval(final Line line, final double a, final double b) {
final double min = Math.min(a, b);
final double max = Math.max(a, b);
final boolean hasMin = Double.isFinite(min);
final boolean hasMax = Double.isFinite(max);
if (hasMin) {
if (hasMax) {
// has both
return new Segment(line, line.toSpace(min), line.toSpace(max));
}
// min only
return new Ray(line, line.toSpace(min));
} else if (hasMax) {
// max only
return new ReverseRay(line, line.toSpace(max));
} else if (Double.isInfinite(min) && Double.isInfinite(max) && Double.compare(min, max) < 0) {
return new LineSpanningSubset(line);
}
throw new IllegalArgumentException(MessageFormat.format(
"Invalid line subset interval: {0}, {1}", Double.toString(a), Double.toString(b)));
}
/** Validate that the actual line is equivalent to the expected line, throwing an exception if not.
* @param expected the expected line
* @param actual the actual line
* @throws IllegalArgumentException if the actual line is not equivalent to the expected line
*/
static void validateLinesEquivalent(final Line expected, final Line actual) {
if (!expected.eq(actual, expected.getPrecision())) {
throw new IllegalArgumentException("Arguments do not represent the same line. Expected " +
expected + " but was " + actual + ".");
}
}
}