| // Copyright 2007 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 Defines a 2-element vector class that can be used for |
| * coordinate math, useful for animation systems and point manipulation. |
| * |
| * Vec2 objects inherit from goog.math.Coordinate and may be used wherever a |
| * Coordinate is required. Where appropriate, Vec2 functions accept both Vec2 |
| * and Coordinate objects as input. |
| * |
| * @author brenneman@google.com (Shawn Brenneman) |
| */ |
| |
| goog.provide('goog.math.Vec2'); |
| |
| goog.require('goog.math'); |
| goog.require('goog.math.Coordinate'); |
| |
| |
| |
| /** |
| * Class for a two-dimensional vector object and assorted functions useful for |
| * manipulating points. |
| * |
| * @param {number} x The x coordinate for the vector. |
| * @param {number} y The y coordinate for the vector. |
| * @struct |
| * @constructor |
| * @extends {goog.math.Coordinate} |
| */ |
| goog.math.Vec2 = function(x, y) { |
| /** |
| * X-value |
| * @type {number} |
| */ |
| this.x = x; |
| |
| /** |
| * Y-value |
| * @type {number} |
| */ |
| this.y = y; |
| }; |
| goog.inherits(goog.math.Vec2, goog.math.Coordinate); |
| |
| |
| /** |
| * @return {!goog.math.Vec2} A random unit-length vector. |
| */ |
| goog.math.Vec2.randomUnit = function() { |
| var angle = Math.random() * Math.PI * 2; |
| return new goog.math.Vec2(Math.cos(angle), Math.sin(angle)); |
| }; |
| |
| |
| /** |
| * @return {!goog.math.Vec2} A random vector inside the unit-disc. |
| */ |
| goog.math.Vec2.random = function() { |
| var mag = Math.sqrt(Math.random()); |
| var angle = Math.random() * Math.PI * 2; |
| |
| return new goog.math.Vec2(Math.cos(angle) * mag, Math.sin(angle) * mag); |
| }; |
| |
| |
| /** |
| * Returns a new Vec2 object from a given coordinate. |
| * @param {!goog.math.Coordinate} a The coordinate. |
| * @return {!goog.math.Vec2} A new vector object. |
| */ |
| goog.math.Vec2.fromCoordinate = function(a) { |
| return new goog.math.Vec2(a.x, a.y); |
| }; |
| |
| |
| /** |
| * @return {!goog.math.Vec2} A new vector with the same coordinates as this one. |
| * @override |
| */ |
| goog.math.Vec2.prototype.clone = function() { |
| return new goog.math.Vec2(this.x, this.y); |
| }; |
| |
| |
| /** |
| * Returns the magnitude of the vector measured from the origin. |
| * @return {number} The length of the vector. |
| */ |
| goog.math.Vec2.prototype.magnitude = function() { |
| return Math.sqrt(this.x * this.x + this.y * this.y); |
| }; |
| |
| |
| /** |
| * Returns the squared magnitude of the vector measured from the origin. |
| * NOTE(brenneman): Leaving out the square root is not a significant |
| * optimization in JavaScript. |
| * @return {number} The length of the vector, squared. |
| */ |
| goog.math.Vec2.prototype.squaredMagnitude = function() { |
| return this.x * this.x + this.y * this.y; |
| }; |
| |
| |
| /** |
| * @return {!goog.math.Vec2} This coordinate after scaling. |
| * @override |
| */ |
| goog.math.Vec2.prototype.scale = |
| /** @type {function(number, number=):!goog.math.Vec2} */ |
| (goog.math.Coordinate.prototype.scale); |
| |
| |
| /** |
| * Reverses the sign of the vector. Equivalent to scaling the vector by -1. |
| * @return {!goog.math.Vec2} The inverted vector. |
| */ |
| goog.math.Vec2.prototype.invert = function() { |
| this.x = -this.x; |
| this.y = -this.y; |
| return this; |
| }; |
| |
| |
| /** |
| * Normalizes the current vector to have a magnitude of 1. |
| * @return {!goog.math.Vec2} The normalized vector. |
| */ |
| goog.math.Vec2.prototype.normalize = function() { |
| return this.scale(1 / this.magnitude()); |
| }; |
| |
| |
| /** |
| * Adds another vector to this vector in-place. |
| * @param {!goog.math.Coordinate} b The vector to add. |
| * @return {!goog.math.Vec2} This vector with {@code b} added. |
| */ |
| goog.math.Vec2.prototype.add = function(b) { |
| this.x += b.x; |
| this.y += b.y; |
| return this; |
| }; |
| |
| |
| /** |
| * Subtracts another vector from this vector in-place. |
| * @param {!goog.math.Coordinate} b The vector to subtract. |
| * @return {!goog.math.Vec2} This vector with {@code b} subtracted. |
| */ |
| goog.math.Vec2.prototype.subtract = function(b) { |
| this.x -= b.x; |
| this.y -= b.y; |
| return this; |
| }; |
| |
| |
| /** |
| * Rotates this vector in-place by a given angle, specified in radians. |
| * @param {number} angle The angle, in radians. |
| * @return {!goog.math.Vec2} This vector rotated {@code angle} radians. |
| */ |
| goog.math.Vec2.prototype.rotate = function(angle) { |
| var cos = Math.cos(angle); |
| var sin = Math.sin(angle); |
| var newX = this.x * cos - this.y * sin; |
| var newY = this.y * cos + this.x * sin; |
| this.x = newX; |
| this.y = newY; |
| return this; |
| }; |
| |
| |
| /** |
| * Rotates a vector by a given angle, specified in radians, relative to a given |
| * axis rotation point. The returned vector is a newly created instance - no |
| * in-place changes are done. |
| * @param {!goog.math.Vec2} v A vector. |
| * @param {!goog.math.Vec2} axisPoint The rotation axis point. |
| * @param {number} angle The angle, in radians. |
| * @return {!goog.math.Vec2} The rotated vector in a newly created instance. |
| */ |
| goog.math.Vec2.rotateAroundPoint = function(v, axisPoint, angle) { |
| var res = v.clone(); |
| return res.subtract(axisPoint).rotate(angle).add(axisPoint); |
| }; |
| |
| |
| /** |
| * Compares this vector with another for equality. |
| * @param {!goog.math.Vec2} b The other vector. |
| * @return {boolean} Whether this vector has the same x and y as the given |
| * vector. |
| */ |
| goog.math.Vec2.prototype.equals = function(b) { |
| return this == b || !!b && this.x == b.x && this.y == b.y; |
| }; |
| |
| |
| /** |
| * Returns the distance between two vectors. |
| * @param {!goog.math.Coordinate} a The first vector. |
| * @param {!goog.math.Coordinate} b The second vector. |
| * @return {number} The distance. |
| */ |
| goog.math.Vec2.distance = goog.math.Coordinate.distance; |
| |
| |
| /** |
| * Returns the squared distance between two vectors. |
| * @param {!goog.math.Coordinate} a The first vector. |
| * @param {!goog.math.Coordinate} b The second vector. |
| * @return {number} The squared distance. |
| */ |
| goog.math.Vec2.squaredDistance = goog.math.Coordinate.squaredDistance; |
| |
| |
| /** |
| * Compares vectors for equality. |
| * @param {!goog.math.Coordinate} a The first vector. |
| * @param {!goog.math.Coordinate} b The second vector. |
| * @return {boolean} Whether the vectors have the same x and y coordinates. |
| */ |
| goog.math.Vec2.equals = goog.math.Coordinate.equals; |
| |
| |
| /** |
| * Returns the sum of two vectors as a new Vec2. |
| * @param {!goog.math.Coordinate} a The first vector. |
| * @param {!goog.math.Coordinate} b The second vector. |
| * @return {!goog.math.Vec2} The sum vector. |
| */ |
| goog.math.Vec2.sum = function(a, b) { |
| return new goog.math.Vec2(a.x + b.x, a.y + b.y); |
| }; |
| |
| |
| /** |
| * Returns the difference between two vectors as a new Vec2. |
| * @param {!goog.math.Coordinate} a The first vector. |
| * @param {!goog.math.Coordinate} b The second vector. |
| * @return {!goog.math.Vec2} The difference vector. |
| */ |
| goog.math.Vec2.difference = function(a, b) { |
| return new goog.math.Vec2(a.x - b.x, a.y - b.y); |
| }; |
| |
| |
| /** |
| * Returns the dot-product of two vectors. |
| * @param {!goog.math.Coordinate} a The first vector. |
| * @param {!goog.math.Coordinate} b The second vector. |
| * @return {number} The dot-product of the two vectors. |
| */ |
| goog.math.Vec2.dot = function(a, b) { |
| return a.x * b.x + a.y * b.y; |
| }; |
| |
| |
| /** |
| * Returns a new Vec2 that is the linear interpolant between vectors a and b at |
| * scale-value x. |
| * @param {!goog.math.Coordinate} a Vector a. |
| * @param {!goog.math.Coordinate} b Vector b. |
| * @param {number} x The proportion between a and b. |
| * @return {!goog.math.Vec2} The interpolated vector. |
| */ |
| goog.math.Vec2.lerp = function(a, b, x) { |
| return new goog.math.Vec2(goog.math.lerp(a.x, b.x, x), |
| goog.math.lerp(a.y, b.y, x)); |
| }; |