1 /*
2 * Copyright (c) 2012, 2014, Oracle and/or its affiliates.
3 * All rights reserved. Use is subject to license terms.
4 *
5 * This file is available and licensed under the following license:
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * - Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * - Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the distribution.
16 * - Neither the name of Oracle Corporation nor the names of its
17 * contributors may be used to endorse or promote products derived
18 * from this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
23 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
24 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
25 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
26 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
30 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32 package com.oracle.javafx.scenebuilder.kit.editor.panel.content.util;
33
34 import javafx.geometry.Point2D;
35
36 /**
37 *
38 *
39 */
40 public class LineEquation {
41
42 private final double x0;
43 private final double y0;
44 private final double x1;
45 private final double y1;
46 private final double distance;
47
48 public LineEquation(double x0, double y0, double x1, double y1) {
49 assert ! ((x0 == x1) && (y0 == y1));
50 this.x0 = x0;
51 this.y0 = y0;
52 this.x1 = x1;
53 this.y1 = y1;
54 final double dx = x1 - x0;
55 final double dy = y1 - y0;
56 this.distance = Math.sqrt(dx * dx + dy * dy);
57 }
58
59 public LineEquation(Point2D p0, Point2D p1) {
60 this(p0.getX(), p0.getY(), p1.getX(), p1.getY());
61 }
62
63 public double getDistance() {
64 return distance;
65 }
66
67 public boolean isValid() {
68 return distance > 0.0;
69 }
70
71 /**
72 * Returns the (x,y) of a target point given its offset along this line.
73 *
74 * @param offset offset of the target point
75 * @return the coordinates of the target point
76 */
77 public Point2D pointAtOffset(double offset) {
78 /*
79 * - offset=0 matches p0
80 * - offset=+D matches p1
81 * - offset < 0 matches line points before p0
82 * - 0 < offset < D matches line points between p0 and p1
83 * - D < offset matches line points after p1
84 *
85 * where D is the distance between p0 and p1
86 */
87 return pointAtP(offsetToP(offset));
88 }
89
90 /**
91 * Projects p on this line and returns the offset of the projected point.
92 *
93 * @param x target point x
94 * @param y target point y
95 * @return the offset of p projection on this line.
96 */
97 public double offsetAtPoint(double x, double y) {
98 /*
99 * offset is the dot product of:
100 * - v1 : vector ((x0, y0), (x, y))
101 * - v2 : normalized vector ((x0, y0), (x1, y1))
102 */
103
104 final double dx1 = x - x0;
105 final double dy1 = y - y0;
106 final double dx2 = (x1 - x0) / distance;
107 final double dy2 = (y1 - y0) / distance;
108 final double result = dx1 * dx2 + dy1 * dy2;
109
110 return result;
111 }
112
113 /**
114 * Returns the (x,y) of a target point given its parametric position.
115 *
116 * @param p parametric position of the target point
117 * @return the coordinates of the target point
118 */
119 public Point2D pointAtP(double p) {
120 final double x, y;
121
122 /*
123 * - p=0 matches p0
124 * - p=1 matches p1
125 * - p < 0 matches line points before p0
126 * - 0 < p < 1 matches line points between p0 and p1
127 * - 1 < p matches line points after p1
128 */
129
130 assert isValid();
131
132 x = x0 + p * (x1 - x0);
133 y = y0 + p * (y1 - y0);
134
135 return new Point2D(x, y);
136 }
137
138 /**
139 * Convert an offset to a parametric position
140 *
141 * @param offset an offset along this line
142 * @return the matching parametric position
143 */
144 public double offsetToP(double offset) {
145 assert isValid();
146 return offset / distance;
147 }
148
149 /**
150 * Convert a parametric position to an offset
151 *
152 * @param p a parametric position
153 * @return the matching offset
154 */
155 public double pToOffset(double p) {
156 assert isValid();
157 return p * distance;
158 }
159 }