Mercurial > dive4elements > river
comparison flys-artifacts/src/main/java/de/intevation/flys/artifacts/geom/VectorUtils.java @ 1797:5eec623db50a
Polygon2D: moved 2D vector operation to separate class.
flys-artifacts/trunk@3120 c6561f87-3c4e-4783-a992-168aeb5c3f6f
| author | Sascha L. Teichmann <sascha.teichmann@intevation.de> |
|---|---|
| date | Mon, 31 Oct 2011 10:03:32 +0000 |
| parents | |
| children | 281b9430c720 |
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| 1796:ae6ace900c07 | 1797:5eec623db50a |
|---|---|
| 1 package de.intevation.flys.geom; | |
| 2 | |
| 3 import java.awt.geom.Point2D; | |
| 4 | |
| 5 public final class VectorUtils | |
| 6 { | |
| 7 public static final double EPSILON = 1e-4; | |
| 8 | |
| 9 private VectorUtils() { | |
| 10 } | |
| 11 | |
| 12 private static final double X(Point2D p) { | |
| 13 return p.getX(); | |
| 14 } | |
| 15 | |
| 16 private static final double Y(Point2D p) { | |
| 17 return p.getY(); | |
| 18 } | |
| 19 | |
| 20 public static final Point2D sub(Point2D a, Point2D b) { | |
| 21 return new Point2D.Double(X(a)-X(b), Y(a)-Y(b)); | |
| 22 } | |
| 23 | |
| 24 public static final double dot(Point2D a, Point2D b) { | |
| 25 return X(a)*X(b) + Y(a)*Y(b); | |
| 26 } | |
| 27 | |
| 28 public static final Point2D add(Point2D a, Point2D b) { | |
| 29 return new Point2D.Double(X(a)+X(b), Y(a)+Y(b)); | |
| 30 } | |
| 31 | |
| 32 public static final Point2D negate(Point2D a) { | |
| 33 return new Point2D.Double(-X(a), -Y(a)); | |
| 34 } | |
| 35 | |
| 36 public static final Point2D ortho(Point2D a) { | |
| 37 return new Point2D.Double(-Y(a), X(a)); | |
| 38 } | |
| 39 | |
| 40 public static final Point2D scale(Point2D a, double s) { | |
| 41 return new Point2D.Double(s*X(a), s*Y(a)); | |
| 42 } | |
| 43 | |
| 44 public static final double lengthSq(Point2D a) { | |
| 45 double x = X(a); | |
| 46 double y = Y(a); | |
| 47 return x*x + y*y; | |
| 48 } | |
| 49 | |
| 50 public static final double length(Point2D a) { | |
| 51 return Math.sqrt(lengthSq(a)); | |
| 52 } | |
| 53 | |
| 54 public static final Point2D normalize(Point2D a) { | |
| 55 double length = length(a); | |
| 56 return length != 0d | |
| 57 ? scale(a, 1d/length) | |
| 58 : new Point2D.Double(X(a), Y(a)); | |
| 59 } | |
| 60 | |
| 61 public static final double L1(Point2D a, Point2D b) { | |
| 62 return Math.abs(X(a)-X(b)) + Math.abs(Y(a)-Y(b)); | |
| 63 } | |
| 64 | |
| 65 public static final boolean collinear(Point2D a, Point2D b, Point2D c) { | |
| 66 double x1 = X(a); | |
| 67 double y1 = Y(a); | |
| 68 double x2 = X(b); | |
| 69 double y2 = Y(b); | |
| 70 double x3 = X(c); | |
| 71 double y3 = Y(c); | |
| 72 | |
| 73 return Math.abs((x2-x1)*(y3-y1)-(y2-y1)*(x3-x1)) < EPSILON; | |
| 74 } | |
| 75 | |
| 76 public static boolean epsilonEquals(Point2D a, Point2D b) { | |
| 77 return Math.abs(X(a)-X(b)) < EPSILON | |
| 78 && Math.abs(Y(a)-Y(b)) < EPSILON; | |
| 79 } | |
| 80 | |
| 81 } | |
| 82 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 : |