Here you can find the source of fractionAlongRay(double px, double py, double qx, double qy, double rx, double ry)
| Parameter | Description |
|---|---|
| px | X coord of reference point |
| py | Y coord of reference point |
| qx | X coord of ray origin |
| qy | Y coord of ray origin |
| rx | X length of ray |
| ry | Y length of ray |
public static double fractionAlongRay(double px, double py, double qx, double qy, double rx, double ry)
//package com.java2s; /*// w ww. j av a 2s . c o m * Copyright 2011 Mark McKay * * Licensed 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. */ public class Main { /** * Calculate the scalar such that when the length of the ray is * multiplied by this scalar, it will provide the closest point * along the ray to the reference point. * * @param px X coord of reference point * @param py Y coord of reference point * @param qx X coord of ray origin * @param qy Y coord of ray origin * @param rx X length of ray * @param ry Y length of ray * @return Scalar of ray */ public static double fractionAlongRay(double px, double py, double qx, double qy, double rx, double ry) { double sx = px - qx; double sy = py - qy; return dot(sx, sy, rx, ry) / dot(rx, ry, rx, ry); } public static double dot(double ax, double ay, double bx, double by) { return ax * bx + ay * by; } public static int dot(int ax, int ay, int bx, int by) { return ax * bx + ay * by; } }