/**
* @license
* Copyright The Closure Library Authors.
* SPDX-License-Identifier: Apache-2.0
*/
/**
* @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.
*/
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) {
'use strict';
/**
* 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() {
'use strict';
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() {
'use strict';
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) {
'use strict';
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() {
'use strict';
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() {
'use strict';
return Math.hypot(this.x, 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() {
'use strict';
return this.x * this.x + this.y * this.y;
};
/**
* @param {number} sx The scale factor to use for the x dimension.
* @param {number=} opt_sy The scale factor to use for the y dimension.
* @return {!goog.math.Vec2} This vector after scaling.
* @override
*/
// Since the implementation of Coordinate.scale() returns "this", we
// can reuse that implementation here, and just recast the return type.
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() {
'use strict';
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() {
'use strict';
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 `b` added.
*/
goog.math.Vec2.prototype.add = function(b) {
'use strict';
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 `b` subtracted.
*/
goog.math.Vec2.prototype.subtract = function(b) {
'use strict';
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 `angle` radians.
*/
goog.math.Vec2.prototype.rotate = function(angle) {
'use strict';
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) {
'use strict';
var res = v.clone();
return res.subtract(axisPoint).rotate(angle).add(axisPoint);
};
/** @override */
goog.math.Vec2.prototype.equals = function(b) {
'use strict';
if (this === b) {
return true;
}
return b instanceof goog.math.Vec2 && !!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) {
'use strict';
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) {
'use strict';
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) {
'use strict';
return a.x * b.x + a.y * b.y;
};
/**
* Returns the determinant of two vectors.
* @param {!goog.math.Vec2} a The first vector.
* @param {!goog.math.Vec2} b The second vector.
* @return {number} The determinant of the two vectors.
*/
goog.math.Vec2.determinant = function(a, b) {
'use strict';
return a.x * b.y - a.y * b.x;
};
/**
* 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) {
'use strict';
return new goog.math.Vec2(
goog.math.lerp(a.x, b.x, x), goog.math.lerp(a.y, b.y, x));
};
/**
* Returns a new Vec2 that is a copy of the vector a, but rescaled by a factors
* sx and sy in the x and y directions. If only sx is specified, then y is
* scaled by the same factor as x.
* @param {!goog.math.Coordinate} a Vector a.
* @param {number} sx X scale factor.
* @param {number=} sy Y scale factor (optional).
* @return {!goog.math.Vec2} A new rescaled vector.
*/
goog.math.Vec2.rescaled = function(a, sx, sy = sx) {
return new goog.math.Vec2(a.x * sx, a.y * sy);
};
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