/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2006-2008, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
package org.geotools.geometry.iso.util.elem2D;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
/**
* @author Jackson Roehrig & Sanjay Jena
*
* Circle2D A circle, representated by a X- and Y- Coordinate and a radius r. This
* class provides a constructor building a unique circle from 3 points.
*
* This class was translated from CPP into Java The original source code can be
* found at http://astronomy.swin.edu.au/~pbourke/geometry/circlefrom3/
*
*
*
* @source $URL$
*/
public class Circle2D {
private double x = 0;
private double y = 0;
private double radius = 0;
public Circle2D(double centerX, double centerY, double radius) {
this.x = centerX;
this.y = centerY;
this.radius = radius;
}
/**
* Constructs a circle from three points
* @param First node
* @param Second node
* @param Thirs node
*/
public Circle2D(Point2D pt1, Point2D pt2, Point2D pt3) {
this.radius=-1; // error checking
if (!this.isPerpendicular(pt1, pt2, pt3) )
this.CalcCircle(pt1, pt2, pt3);
else if (!this.isPerpendicular(pt1, pt3, pt2) )
this.CalcCircle(pt1, pt3, pt2);
else if (!this.isPerpendicular(pt2, pt1, pt3) )
this.CalcCircle(pt2, pt1, pt3);
else if (!this.isPerpendicular(pt2, pt3, pt1) )
this.CalcCircle(pt2, pt3, pt1);
else if (!this.isPerpendicular(pt3, pt2, pt1) )
this.CalcCircle(pt3, pt2, pt1);
else if (!this.isPerpendicular(pt3, pt1, pt2) )
this.CalcCircle(pt3, pt1, pt2);
else {
throw new IllegalArgumentException("The three pts are perpendicular to axis\n");
}
}
// Check the given node are perpendicular to x or y axis
private boolean isPerpendicular(Point2D pt1, Point2D pt2, Point2D pt3) {
double yDelta_a= pt2.getY() - pt1.getY();
double xDelta_a= pt2.getX() - pt1.getX();
double yDelta_b= pt3.getY() - pt2.getY();
double xDelta_b= pt3.getX() - pt2.getX();
// checking whether the line of the two pts are vertical
if (Math.abs(xDelta_a) <= 0.000000001 && Math.abs(yDelta_b) <= 0.000000001){
return false;
}
return ((Math.abs(yDelta_a) <= 0.0000001) ||
(Math.abs(yDelta_b) <= 0.0000001) ||
(Math.abs(xDelta_a) <= 0.000000001) ||
(Math.abs(xDelta_b) <= 0.000000001));
}
private double CalcCircle(Point2D pt1, Point2D pt2, Point2D pt3)
{
double yDelta_a= pt2.getY() - pt1.getY();
double xDelta_a= pt2.getX() - pt1.getX();
double yDelta_b= pt3.getY() - pt2.getY();
double xDelta_b= pt3.getX() - pt2.getX();
if (Math.abs(xDelta_a) <= 0.000000001 && Math.abs(yDelta_b) <= 0.000000001){
this.x= 0.5*(pt2.getX() + pt3.getX());
this.y= 0.5*(pt1.getY() + pt2.getY());
this.radius= pt1.distance(this.getCenter());
return this.radius;
}
// IsPerpendicular() assure that xDelta(s) are not zero
double aSlope=yDelta_a/xDelta_a;
double bSlope=yDelta_b/xDelta_b;
if (Math.abs(aSlope-bSlope) <= 0.000000001) {
// checking whether the given points are colinear.
throw new IllegalArgumentException("The three pts are colinear\n");
}
// calc center
this.x= (aSlope*bSlope*(pt1.getY() - pt3.getY()) + bSlope*(pt1.getX() + pt2.getX())
- aSlope*(pt2.getX() + pt3.getX()) )/(2* (bSlope-aSlope) );
this.y = -1*(this.x - (pt1.getX() + pt2.getX())/2)/aSlope + (pt1.getY() + pt2.getY())/2;
this.radius= pt1.distance(this.getCenter());
return this.radius;
}
/**
*
* @return
*/
public double getX() {
return this.x;
}
/**
*
* @return
*/
public double getY() {
return this.y;
}
/**
*
* @return
*/
public double getRadius() {
return this.radius;
}
/**
*
* @return
*/
public Point2D getCenter() {
return new Point2D.Double(this.x, this.y);
}
/**
* @param radius The radius to set.
*/
public void setRadius(double radius) {
this.radius = radius;
}
/**
* @param x The x to set.
*/
public void setX(double x) {
this.x = x;
}
/**
* @param y The y to set.
*/
public void setY(double y) {
this.y = y;
}
public void setValues(double x, double y, double radius) {
this.x = x;
this.y = y;
this.radius = radius;
}
/**
* Verifies weather the circle contains a node or not.
* Point laying at the border of the circle are not contained by the circle.
* @param dp
* @return
*/
public boolean contains(Point2D dp) {
double dx = this.x - dp.getX();
double dy = this.y - dp.getY();
return ((dx*dx) + (dy*dy)) < (this.radius*this.radius);
}
public Rectangle2D getRectangle() {
return new Rectangle2D.Double(x-radius,y-radius,2*radius,2*radius);
}
public String toString() {
return "Circle2D: X:"+this.x+" Y:"+this.y+" r:"+this.radius;
}
}