Simon Hunt | 1c21989 | 2014-10-22 16:32:39 -0700 | [diff] [blame] | 1 | /* |
Thomas Vachuska | 781d18b | 2014-10-27 10:31:25 -0700 | [diff] [blame^] | 2 | * Licensed to the Apache Software Foundation (ASF) under one |
| 3 | * or more contributor license agreements. See the NOTICE file |
| 4 | * distributed with this work for additional information |
| 5 | * regarding copyright ownership. The ASF licenses this file |
| 6 | * to you under the Apache License, Version 2.0 (the |
| 7 | * "License"); you may not use this file except in compliance |
| 8 | * with the License. You may obtain a copy of the License at |
| 9 | * |
| 10 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 11 | * |
| 12 | * Unless required by applicable law or agreed to in writing, |
| 13 | * software distributed under the License is distributed on an |
| 14 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| 15 | * KIND, either express or implied. See the License for the |
| 16 | * specific language governing permissions and limitations |
| 17 | * under the License. |
| 18 | */ |
| 19 | |
| 20 | /* |
Simon Hunt | 1c21989 | 2014-10-22 16:32:39 -0700 | [diff] [blame] | 21 | Geometry library - based on work by Mike Bostock. |
| 22 | */ |
| 23 | |
| 24 | (function() { |
| 25 | |
| 26 | if (typeof geo == 'undefined') { |
| 27 | geo = {}; |
| 28 | } |
| 29 | |
| 30 | var tolerance = 1e-10; |
| 31 | |
| 32 | function eq(a, b) { |
| 33 | return (Math.abs(a - b) < tolerance); |
| 34 | } |
| 35 | |
| 36 | function gt(a, b) { |
| 37 | return (a - b > -tolerance); |
| 38 | } |
| 39 | |
| 40 | function lt(a, b) { |
| 41 | return gt(b, a); |
| 42 | } |
| 43 | |
| 44 | geo.eq = eq; |
| 45 | geo.gt = gt; |
| 46 | geo.lt = lt; |
| 47 | |
| 48 | geo.LineSegment = function(x1, y1, x2, y2) { |
| 49 | this.x1 = x1; |
| 50 | this.y1 = y1; |
| 51 | this.x2 = x2; |
| 52 | this.y2 = y2; |
| 53 | |
| 54 | // Ax + By = C |
| 55 | this.a = y2 - y1; |
| 56 | this.b = x1 - x2; |
| 57 | this.c = x1 * this.a + y1 * this.b; |
| 58 | |
| 59 | if (eq(this.a, 0) && eq(this.b, 0)) { |
| 60 | throw new Error( |
| 61 | 'Cannot construct a LineSegment with two equal endpoints.'); |
| 62 | } |
| 63 | }; |
| 64 | |
| 65 | geo.LineSegment.prototype.intersect = function(that) { |
| 66 | var d = (this.x1 - this.x2) * (that.y1 - that.y2) - |
| 67 | (this.y1 - this.y2) * (that.x1 - that.x2); |
| 68 | |
| 69 | if (eq(d, 0)) { |
| 70 | // The two lines are parallel or very close. |
| 71 | return { |
| 72 | x : NaN, |
| 73 | y : NaN |
| 74 | }; |
| 75 | } |
| 76 | |
| 77 | var t1 = this.x1 * this.y2 - this.y1 * this.x2, |
| 78 | t2 = that.x1 * that.y2 - that.y1 * that.x2, |
| 79 | x = (t1 * (that.x1 - that.x2) - t2 * (this.x1 - this.x2)) / d, |
| 80 | y = (t1 * (that.y1 - that.y2) - t2 * (this.y1 - this.y2)) / d, |
| 81 | in1 = (gt(x, Math.min(this.x1, this.x2)) && lt(x, Math.max(this.x1, this.x2)) && |
| 82 | gt(y, Math.min(this.y1, this.y2)) && lt(y, Math.max(this.y1, this.y2))), |
| 83 | in2 = (gt(x, Math.min(that.x1, that.x2)) && lt(x, Math.max(that.x1, that.x2)) && |
| 84 | gt(y, Math.min(that.y1, that.y2)) && lt(y, Math.max(that.y1, that.y2))); |
| 85 | |
| 86 | return { |
| 87 | x : x, |
| 88 | y : y, |
| 89 | in1 : in1, |
| 90 | in2 : in2 |
| 91 | }; |
| 92 | }; |
| 93 | |
| 94 | geo.LineSegment.prototype.x = function(y) { |
| 95 | // x = (C - By) / a; |
| 96 | if (this.a) { |
| 97 | return (this.c - this.b * y) / this.a; |
| 98 | } else { |
| 99 | // a == 0 -> horizontal line |
| 100 | return NaN; |
| 101 | } |
| 102 | }; |
| 103 | |
| 104 | geo.LineSegment.prototype.y = function(x) { |
| 105 | // y = (C - Ax) / b; |
| 106 | if (this.b) { |
| 107 | return (this.c - this.a * x) / this.b; |
| 108 | } else { |
| 109 | // b == 0 -> vertical line |
| 110 | return NaN; |
| 111 | } |
| 112 | }; |
| 113 | |
| 114 | geo.LineSegment.prototype.length = function() { |
| 115 | return Math.sqrt( |
| 116 | (this.y2 - this.y1) * (this.y2 - this.y1) + |
| 117 | (this.x2 - this.x1) * (this.x2 - this.x1)); |
| 118 | }; |
| 119 | |
| 120 | geo.LineSegment.prototype.offset = function(x, y) { |
| 121 | return new geo.LineSegment( |
| 122 | this.x1 + x, this.y1 + y, |
| 123 | this.x2 + x, this.y2 + y); |
| 124 | }; |
| 125 | |
| 126 | })(); |