| // Copyright 2008 The Closure Library Authors. All Rights Reserved. |
| // |
| // 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. |
| |
| |
| /** |
| * @fileoverview Represents a line in 2D space. |
| * |
| * @author robbyw@google.com (Robby Walker) |
| */ |
| |
| goog.provide('goog.math.Line'); |
| |
| goog.require('goog.math'); |
| goog.require('goog.math.Coordinate'); |
| |
| |
| |
| /** |
| * Object representing a line. |
| * @param {number} x0 X coordinate of the start point. |
| * @param {number} y0 Y coordinate of the start point. |
| * @param {number} x1 X coordinate of the end point. |
| * @param {number} y1 Y coordinate of the end point. |
| * @struct |
| * @constructor |
| * @final |
| */ |
| goog.math.Line = function(x0, y0, x1, y1) { |
| /** |
| * X coordinate of the first point. |
| * @type {number} |
| */ |
| this.x0 = x0; |
| |
| /** |
| * Y coordinate of the first point. |
| * @type {number} |
| */ |
| this.y0 = y0; |
| |
| /** |
| * X coordinate of the first control point. |
| * @type {number} |
| */ |
| this.x1 = x1; |
| |
| /** |
| * Y coordinate of the first control point. |
| * @type {number} |
| */ |
| this.y1 = y1; |
| }; |
| |
| |
| /** |
| * @return {!goog.math.Line} A copy of this line. |
| */ |
| goog.math.Line.prototype.clone = function() { |
| return new goog.math.Line(this.x0, this.y0, this.x1, this.y1); |
| }; |
| |
| |
| /** |
| * Tests whether the given line is exactly the same as this one. |
| * @param {goog.math.Line} other The other line. |
| * @return {boolean} Whether the given line is the same as this one. |
| */ |
| goog.math.Line.prototype.equals = function(other) { |
| return this.x0 == other.x0 && this.y0 == other.y0 && |
| this.x1 == other.x1 && this.y1 == other.y1; |
| }; |
| |
| |
| /** |
| * @return {number} The squared length of the line segment used to define the |
| * line. |
| */ |
| goog.math.Line.prototype.getSegmentLengthSquared = function() { |
| var xdist = this.x1 - this.x0; |
| var ydist = this.y1 - this.y0; |
| return xdist * xdist + ydist * ydist; |
| }; |
| |
| |
| /** |
| * @return {number} The length of the line segment used to define the line. |
| */ |
| goog.math.Line.prototype.getSegmentLength = function() { |
| return Math.sqrt(this.getSegmentLengthSquared()); |
| }; |
| |
| |
| /** |
| * Computes the interpolation parameter for the point on the line closest to |
| * a given point. |
| * @param {number|goog.math.Coordinate} x The x coordinate of the point, or |
| * a coordinate object. |
| * @param {number=} opt_y The y coordinate of the point - required if x is a |
| * number, ignored if x is a goog.math.Coordinate. |
| * @return {number} The interpolation parameter of the point on the line |
| * closest to the given point. |
| * @private |
| */ |
| goog.math.Line.prototype.getClosestLinearInterpolation_ = function(x, opt_y) { |
| var y; |
| if (x instanceof goog.math.Coordinate) { |
| y = x.y; |
| x = x.x; |
| } else { |
| y = opt_y; |
| } |
| |
| var x0 = this.x0; |
| var y0 = this.y0; |
| |
| var xChange = this.x1 - x0; |
| var yChange = this.y1 - y0; |
| |
| return ((x - x0) * xChange + (y - y0) * yChange) / |
| this.getSegmentLengthSquared(); |
| }; |
| |
| |
| /** |
| * Returns the point on the line segment proportional to t, where for t = 0 we |
| * return the starting point and for t = 1 we return the end point. For t < 0 |
| * or t > 1 we extrapolate along the line defined by the line segment. |
| * @param {number} t The interpolation parameter along the line segment. |
| * @return {!goog.math.Coordinate} The point on the line segment at t. |
| */ |
| goog.math.Line.prototype.getInterpolatedPoint = function(t) { |
| return new goog.math.Coordinate( |
| goog.math.lerp(this.x0, this.x1, t), |
| goog.math.lerp(this.y0, this.y1, t)); |
| }; |
| |
| |
| /** |
| * Computes the point on the line closest to a given point. Note that a line |
| * in this case is defined as the infinite line going through the start and end |
| * points. To find the closest point on the line segment itself see |
| * {@see #getClosestSegmentPoint}. |
| * @param {number|goog.math.Coordinate} x The x coordinate of the point, or |
| * a coordinate object. |
| * @param {number=} opt_y The y coordinate of the point - required if x is a |
| * number, ignored if x is a goog.math.Coordinate. |
| * @return {!goog.math.Coordinate} The point on the line closest to the given |
| * point. |
| */ |
| goog.math.Line.prototype.getClosestPoint = function(x, opt_y) { |
| return this.getInterpolatedPoint( |
| this.getClosestLinearInterpolation_(x, opt_y)); |
| }; |
| |
| |
| /** |
| * Computes the point on the line segment closest to a given point. |
| * @param {number|goog.math.Coordinate} x The x coordinate of the point, or |
| * a coordinate object. |
| * @param {number=} opt_y The y coordinate of the point - required if x is a |
| * number, ignored if x is a goog.math.Coordinate. |
| * @return {!goog.math.Coordinate} The point on the line segment closest to the |
| * given point. |
| */ |
| goog.math.Line.prototype.getClosestSegmentPoint = function(x, opt_y) { |
| return this.getInterpolatedPoint( |
| goog.math.clamp(this.getClosestLinearInterpolation_(x, opt_y), 0, 1)); |
| }; |