set up a weak link between a line and its reverse to avoid duplications.
Project: http://git-wip-us.apache.org/repos/asf/commons-math/repo Commit: http://git-wip-us.apache.org/repos/asf/commons-math/commit/84cf29ec Tree: http://git-wip-us.apache.org/repos/asf/commons-math/tree/84cf29ec Diff: http://git-wip-us.apache.org/repos/asf/commons-math/diff/84cf29ec Branch: refs/heads/master Commit: 84cf29ecf31c67c7640f8821d4fdda625a173aa6 Parents: 6525cc4 Author: Luc Maisonobe <l...@apache.org> Authored: Tue Dec 2 15:37:15 2014 +0100 Committer: Luc Maisonobe <l...@apache.org> Committed: Tue Dec 2 15:37:15 2014 +0100 ---------------------------------------------------------------------- .../math3/geometry/euclidean/twod/Line.java | 39 ++++++++++++++++++-- 1 file changed, 36 insertions(+), 3 deletions(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/commons-math/blob/84cf29ec/src/main/java/org/apache/commons/math3/geometry/euclidean/twod/Line.java ---------------------------------------------------------------------- diff --git a/src/main/java/org/apache/commons/math3/geometry/euclidean/twod/Line.java b/src/main/java/org/apache/commons/math3/geometry/euclidean/twod/Line.java index b40f0fa..d6fd487 100644 --- a/src/main/java/org/apache/commons/math3/geometry/euclidean/twod/Line.java +++ b/src/main/java/org/apache/commons/math3/geometry/euclidean/twod/Line.java @@ -80,6 +80,9 @@ public class Line implements Hyperplane<Euclidean2D>, Embedding<Euclidean2D, Euc /** Tolerance below which points are considered identical. */ private final double tolerance; + /** Reverse line. */ + private Line reverse; + /** Build a line from two points. * <p>The line is oriented from p1 to p2</p> * @param p1 first point @@ -118,6 +121,7 @@ public class Line implements Hyperplane<Euclidean2D>, Embedding<Euclidean2D, Euc this.sin = sin; this.originOffset = originOffset; this.tolerance = tolerance; + this.reverse = null; } /** Build a line from two points. @@ -152,6 +156,7 @@ public class Line implements Hyperplane<Euclidean2D>, Embedding<Euclidean2D, Euc sin = line.sin; originOffset = line.originOffset; tolerance = line.tolerance; + reverse = null; } /** {@inheritDoc} */ @@ -165,6 +170,7 @@ public class Line implements Hyperplane<Euclidean2D>, Embedding<Euclidean2D, Euc * @param p2 second point */ public void reset(final Vector2D p1, final Vector2D p2) { + unlinkReverse(); final double dx = p2.getX() - p1.getX(); final double dy = p2.getY() - p1.getY(); final double d = FastMath.hypot(dx, dy); @@ -186,6 +192,7 @@ public class Line implements Hyperplane<Euclidean2D>, Embedding<Euclidean2D, Euc * @param alpha angle of the line with respect to abscissa axis */ public void reset(final Vector2D p, final double alpha) { + unlinkReverse(); this.angle = MathUtils.normalizeAngle(alpha, FastMath.PI); cos = FastMath.cos(this.angle); sin = FastMath.sin(this.angle); @@ -195,6 +202,7 @@ public class Line implements Hyperplane<Euclidean2D>, Embedding<Euclidean2D, Euc /** Revert the instance. */ public void revertSelf() { + unlinkReverse(); if (angle < FastMath.PI) { angle += FastMath.PI; } else { @@ -205,14 +213,37 @@ public class Line implements Hyperplane<Euclidean2D>, Embedding<Euclidean2D, Euc originOffset = -originOffset; } + /** Unset the link between an instance and its reverse. + */ + private void unlinkReverse() { + if (reverse != null) { + reverse.reverse = null; + } + reverse = null; + } + /** Get the reverse of the instance. * <p>Get a line with reversed orientation with respect to the - * instance. A new object is built, the instance is untouched.</p> + * instance.</p> + * <p> + * As long as neither the instance nor its reverse are modified + * (i.e. as long as none of the {@link #reset(Vector2D, Vector2D)}, + * {@link #reset(Vector2D, double)}, {@link #revertSelf()}, + * {@link #setAngle(double)} or {@link #setOriginOffset(double)} + * methods are called), then the line and its reverse remain linked + * together so that {@code line.getReverse().getReverse() == line}. + * When one of the line is modified, the link is deleted as both + * instance becomes independent. + * </p> * @return a new line, with orientation opposite to the instance orientation */ public Line getReverse() { - return new Line((angle < FastMath.PI) ? (angle + FastMath.PI) : (angle - FastMath.PI), - -cos, -sin, -originOffset, tolerance); + if (reverse == null) { + reverse = new Line((angle < FastMath.PI) ? (angle + FastMath.PI) : (angle - FastMath.PI), + -cos, -sin, -originOffset, tolerance); + reverse.reverse = this; + } + return reverse; } /** Transform a space point into a sub-space point. @@ -383,6 +414,7 @@ public class Line implements Hyperplane<Euclidean2D>, Embedding<Euclidean2D, Euc * @param angle new angle of the line with respect to the abscissa axis */ public void setAngle(final double angle) { + unlinkReverse(); this.angle = MathUtils.normalizeAngle(angle, FastMath.PI); cos = FastMath.cos(this.angle); sin = FastMath.sin(this.angle); @@ -399,6 +431,7 @@ public class Line implements Hyperplane<Euclidean2D>, Embedding<Euclidean2D, Euc * @param offset offset of the origin */ public void setOriginOffset(final double offset) { + unlinkReverse(); originOffset = offset; }
