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Diffstat (limited to 'src/main/java/org/apache/commons/math3/geometry/euclidean/twod/Segment.java')
-rw-r--r-- | src/main/java/org/apache/commons/math3/geometry/euclidean/twod/Segment.java | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/src/main/java/org/apache/commons/math3/geometry/euclidean/twod/Segment.java b/src/main/java/org/apache/commons/math3/geometry/euclidean/twod/Segment.java new file mode 100644 index 0000000..2ef7f4e --- /dev/null +++ b/src/main/java/org/apache/commons/math3/geometry/euclidean/twod/Segment.java @@ -0,0 +1,112 @@ +/* + * 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.twod; + +import org.apache.commons.math3.geometry.Point; +import org.apache.commons.math3.util.FastMath; + +/** Simple container for a two-points segment. + * @since 3.0 + */ +public class Segment { + + /** Start point of the segment. */ + private final Vector2D start; + + /** End point of the segment. */ + private final Vector2D end; + + /** Line containing the segment. */ + private final Line line; + + /** Build a segment. + * @param start start point of the segment + * @param end end point of the segment + * @param line line containing the segment + */ + public Segment(final Vector2D start, final Vector2D end, final Line line) { + this.start = start; + this.end = end; + this.line = line; + } + + /** Get the start point of the segment. + * @return start point of the segment + */ + public Vector2D getStart() { + return start; + } + + /** Get the end point of the segment. + * @return end point of the segment + */ + public Vector2D getEnd() { + return end; + } + + /** Get the line containing the segment. + * @return line containing the segment + */ + public Line getLine() { + return line; + } + + /** Calculates the shortest distance from a point to this line segment. + * <p> + * If the perpendicular extension from the point to the line does not + * cross in the bounds of the line segment, the shortest distance to + * the two end points will be returned. + * </p> + * + * Algorithm adapted from: + * <a href="http://www.codeguru.com/forum/printthread.php?s=cc8cf0596231f9a7dba4da6e77c29db3&t=194400&pp=15&page=1"> + * Thread @ Codeguru</a> + * + * @param p to check + * @return distance between the instance and the point + * @since 3.1 + */ + public double distance(final Vector2D p) { + final double deltaX = end.getX() - start.getX(); + final double deltaY = end.getY() - start.getY(); + + final double r = ((p.getX() - start.getX()) * deltaX + (p.getY() - start.getY()) * deltaY) / + (deltaX * deltaX + deltaY * deltaY); + + // r == 0 => P = startPt + // r == 1 => P = endPt + // r < 0 => P is on the backward extension of the segment + // r > 1 => P is on the forward extension of the segment + // 0 < r < 1 => P is on the segment + + // if point isn't on the line segment, just return the shortest distance to the end points + if (r < 0 || r > 1) { + final double dist1 = getStart().distance((Point<Euclidean2D>) p); + final double dist2 = getEnd().distance((Point<Euclidean2D>) p); + + return FastMath.min(dist1, dist2); + } + else { + // find point on line and see if it is in the line segment + final double px = start.getX() + r * deltaX; + final double py = start.getY() + r * deltaY; + + final Vector2D interPt = new Vector2D(px, py); + return interPt.distance((Point<Euclidean2D>) p); + } + } +} |