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With inspiration from other libraries
/*
* 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.math3.geometry.euclidean.threed;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.math3.exception.MathIllegalArgumentException;
import org.apache.commons.math3.geometry.Point;
import org.apache.commons.math3.geometry.euclidean.oned.Euclidean1D;
import org.apache.commons.math3.geometry.euclidean.oned.Interval;
import org.apache.commons.math3.geometry.euclidean.oned.IntervalsSet;
import org.apache.commons.math3.geometry.euclidean.oned.Vector1D;
import org.apache.commons.math3.geometry.partitioning.Region.Location;
/** This class represents a subset of a {@link Line}.
* @since 3.0
*/
public class SubLine {
/** Default value for tolerance. */
private static final double DEFAULT_TOLERANCE = 1.0e-10;
/** Underlying line. */
private final Line line;
/** Remaining region of the hyperplane. */
private final IntervalsSet remainingRegion;
/** Simple constructor.
* @param line underlying line
* @param remainingRegion remaining region of the line
*/
public SubLine(final Line line, final IntervalsSet remainingRegion) {
this.line = line;
this.remainingRegion = remainingRegion;
}
/** Create a sub-line from two endpoints.
* @param start start point
* @param end end point
* @param tolerance tolerance below which points are considered identical
* @exception MathIllegalArgumentException if the points are equal
* @since 3.3
*/
public SubLine(final Vector3D start, final Vector3D end, final double tolerance)
throws MathIllegalArgumentException {
this(new Line(start, end, tolerance), buildIntervalSet(start, end, tolerance));
}
/** Create a sub-line from two endpoints.
* @param start start point
* @param end end point
* @exception MathIllegalArgumentException if the points are equal
* @deprecated as of 3.3, replaced with {@link #SubLine(Vector3D, Vector3D, double)}
*/
public SubLine(final Vector3D start, final Vector3D end)
throws MathIllegalArgumentException {
this(start, end, DEFAULT_TOLERANCE);
}
/** Create a sub-line from a segment.
* @param segment single segment forming the sub-line
* @exception MathIllegalArgumentException if the segment endpoints are equal
*/
public SubLine(final Segment segment) throws MathIllegalArgumentException {
this(segment.getLine(),
buildIntervalSet(segment.getStart(), segment.getEnd(), segment.getLine().getTolerance()));
}
/** Get the endpoints of the sub-line.
*
* A subline may be any arbitrary number of disjoints segments, so the endpoints
* are provided as a list of endpoint pairs. Each element of the list represents
* one segment, and each segment contains a start point at index 0 and an end point
* at index 1. If the sub-line is unbounded in the negative infinity direction,
* the start point of the first segment will have infinite coordinates. If the
* sub-line is unbounded in the positive infinity direction, the end point of the
* last segment will have infinite coordinates. So a sub-line covering the whole
* line will contain just one row and both elements of this row will have infinite
* coordinates. If the sub-line is empty, the returned list will contain 0 segments.
*
* @return list of segments endpoints
*/
public List getSegments() {
final List list = remainingRegion.asList();
final List segments = new ArrayList(list.size());
for (final Interval interval : list) {
final Vector3D start = line.toSpace((Point) new Vector1D(interval.getInf()));
final Vector3D end = line.toSpace((Point) new Vector1D(interval.getSup()));
segments.add(new Segment(start, end, line));
}
return segments;
}
/** Get the intersection of the instance and another sub-line.
*
* This method is related to the {@link Line#intersection(Line)
* intersection} method in the {@link Line Line} class, but in addition
* to compute the point along infinite lines, it also checks the point
* lies on both sub-line ranges.
*
* @param subLine other sub-line which may intersect instance
* @param includeEndPoints if true, endpoints are considered to belong to
* instance (i.e. they are closed sets) and may be returned, otherwise endpoints
* are considered to not belong to instance (i.e. they are open sets) and intersection
* occurring on endpoints lead to null being returned
* @return the intersection point if there is one, null if the sub-lines don't intersect
*/
public Vector3D intersection(final SubLine subLine, final boolean includeEndPoints) {
// compute the intersection on infinite line
Vector3D v1D = line.intersection(subLine.line);
if (v1D == null) {
return null;
}
// check location of point with respect to first sub-line
Location loc1 = remainingRegion.checkPoint((Point) line.toSubSpace((Point) v1D));
// check location of point with respect to second sub-line
Location loc2 = subLine.remainingRegion.checkPoint((Point) subLine.line.toSubSpace((Point) v1D));
if (includeEndPoints) {
return ((loc1 != Location.OUTSIDE) && (loc2 != Location.OUTSIDE)) ? v1D : null;
} else {
return ((loc1 == Location.INSIDE) && (loc2 == Location.INSIDE)) ? v1D : null;
}
}
/** Build an interval set from two points.
* @param start start point
* @param end end point
* @return an interval set
* @param tolerance tolerance below which points are considered identical
* @exception MathIllegalArgumentException if the points are equal
*/
private static IntervalsSet buildIntervalSet(final Vector3D start, final Vector3D end, final double tolerance)
throws MathIllegalArgumentException {
final Line line = new Line(start, end, tolerance);
return new IntervalsSet(line.toSubSpace((Point) start).getX(),
line.toSubSpace((Point) end).getX(),
tolerance);
}
}