Java Geometry Circle circleCentre(double x1, double y1, double x2, double y2, double x3, double y3)

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  5. circleCentre(double x1, double y1, double x2, double y2, double x3, double y3)

Description

Returns a circle passing by the 3 given points.

License

Apache License

Parameter

Parameter Description
x1 <var>x</var> value of the first point.
y1 <var>y</var> value of the first point.
x2 <var>x</var> value of the second point.
y2 <var>y</var> value of the second point.
x3 <var>x</var> value of the third point.
y3 <var>y</var> value of the third point.

Return

A circle passing by the given points.

Declaration 

public static Point2D.Double circleCentre(double x1, double y1, double x2, double y2, double x3, double y3)

Method Source Code

//package com.java2s;
/*//  ww w. j  ava 2 s.  c  o  m
 * 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.
 */

import java.awt.geom.Point2D;

public class Main {
    /**
     * Returns a circle passing by the 3 given points. The distance between the returned
     * point and any of the given points will be constant; it is the circle radius.
     *
     * @param  x1 <var>x</var> value of the first  point.
     * @param  y1 <var>y</var> value of the first  point.
     * @param  x2 <var>x</var> value of the second point.
     * @param  y2 <var>y</var> value of the second point.
     * @param  x3 <var>x</var> value of the third  point.
     * @param  y3 <var>y</var> value of the third  point.
     * @return A circle passing by the given points.
     *
     * @todo This method is used by Geotk (a sandbox for code that may migrate to SIS), but not yet by SIS.
     *       We temporarily keep this code here, but may delete or move it elsewhere in a future SIS version
     *       depending whether we port to SIS the sandbox code.
     */
    public static Point2D.Double circleCentre(double x1, double y1, double x2, double y2, double x3, double y3) {
        x2 -= x1;
        x3 -= x1;
        y2 -= y1;
        y3 -= y1;
        final double sq2 = (x2 * x2 + y2 * y2);
        final double sq3 = (x3 * x3 + y3 * y3);
        final double x = (y2 * sq3 - y3 * sq2) / (y2 * x3 - y3 * x2);
        return new Point2D.Double(x1 + 0.5 * x, y1 + 0.5 * (sq2 - x * x2) / y2);
    }
}

Related

  1. circle2poly(float x, float y, float radius)
  2. circleArrow(double size)
  3. circleCentre(double x1, double y1, double x2, double y2, double x3, double y3)
  4. pCircle(int x, int y, int r)