sascha@1797: package de.intevation.flys.geom;
sascha@1797: 
sascha@1797: import java.awt.geom.Point2D;
sascha@1797: 
sascha@1797: public final class VectorUtils
sascha@1797: {
sascha@1797:     public static final double EPSILON = 1e-4;
sascha@1797: 
sascha@1797:     private VectorUtils() {
sascha@1797:     }
sascha@1797: 
sascha@1799:     public static final double X(Point2D p) {
sascha@1797:         return p.getX();
sascha@1797:     }
sascha@1797: 
sascha@1799:     public static final double Y(Point2D p) {
sascha@1797:         return p.getY();
sascha@1797:     }
sascha@1797: 
sascha@1797:     public static final Point2D sub(Point2D a, Point2D b) {
sascha@1797:         return new Point2D.Double(X(a)-X(b), Y(a)-Y(b));
sascha@1797:     }
sascha@1797: 
sascha@1797:     public static final double dot(Point2D a, Point2D b) {
sascha@1797:         return X(a)*X(b) + Y(a)*Y(b);
sascha@1797:     }
sascha@1797: 
sascha@1797:     public static final Point2D add(Point2D a, Point2D b) {
sascha@1797:         return new Point2D.Double(X(a)+X(b), Y(a)+Y(b));
sascha@1797:     }
sascha@1797: 
sascha@1797:     public static final Point2D negate(Point2D a) {
sascha@1797:         return new Point2D.Double(-X(a), -Y(a));
sascha@1797:     }
sascha@1797: 
sascha@1797:     public static final Point2D ortho(Point2D a) {
sascha@1797:         return new Point2D.Double(-Y(a), X(a));
sascha@1797:     }
sascha@1797: 
sascha@1797:     public static final Point2D scale(Point2D a, double s) {
sascha@1797:         return new Point2D.Double(s*X(a), s*Y(a));
sascha@1797:     }
sascha@1797: 
sascha@1797:     public static final double lengthSq(Point2D a) {
sascha@1797:         double x = X(a);
sascha@1797:         double y = Y(a);
sascha@1797:         return x*x + y*y;
sascha@1797:     }
sascha@1797: 
sascha@1797:     public static final double length(Point2D a) {
sascha@1797:         return Math.sqrt(lengthSq(a));
sascha@1797:     }
sascha@1797: 
sascha@1797:     public static final Point2D normalize(Point2D a) {
sascha@1797:         double length = length(a);
sascha@1797:         return length != 0d
sascha@1797:             ? scale(a, 1d/length) 
sascha@1797:             : new Point2D.Double(X(a), Y(a));
sascha@1797:     }
sascha@1797: 
sascha@1797:     public static final double L1(Point2D a, Point2D b) {
sascha@1797:         return Math.abs(X(a)-X(b)) + Math.abs(Y(a)-Y(b));
sascha@1797:     }
sascha@1797: 
sascha@1797:     public static final boolean collinear(Point2D a, Point2D b, Point2D c) {
sascha@1797:         double x1 = X(a);
sascha@1797:         double y1 = Y(a);
sascha@1797:         double x2 = X(b);
sascha@1797:         double y2 = Y(b);
sascha@1797:         double x3 = X(c);
sascha@1797:         double y3 = Y(c);
sascha@1797: 
sascha@1797:         return Math.abs((x2-x1)*(y3-y1)-(y2-y1)*(x3-x1)) < EPSILON;
sascha@1797:     }
sascha@1797: 
sascha@1797:     public static boolean epsilonEquals(Point2D a, Point2D b) {
sascha@1797:         return Math.abs(X(a)-X(b)) < EPSILON 
sascha@1797:             && Math.abs(Y(a)-Y(b)) < EPSILON;
sascha@1797:     }
sascha@1797: 
sascha@1797: }
sascha@1797: // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :