Vec2.js

A generic library useful when you need to work with points/vectors in 2d space.

Use

  var a = new Vec2(10, 10), // new keyword
      b = Vec2(100, 10); // call the constructor directly

  console.log(a.distance(b)); // 90

Stuff to Note: most of the Vec2's methods take a returnNew as the last parameter. If passed a truthy value, a new vector will be returned to you. Otherwise the operation will be applied to this and this will be returned.

Also, since Infinityand NaN are so insidious, this library will throw as soon as it detects either of these so you can take action to fix your data/algorithm.

Supported operations

change([fn])

Add an observer fn that will be called whenever this vector changes. Calling this method without a function causes it to notify observers.

fn signature: function(vec, prev) {} - where prev is a clone of the vector before the last operation.

this function returns the passed fn

returns: Vec2

ignore([fn])

Pass a fn to remove it from the observers list. Calling this function without a fn will remove all observers.

returns: Vec2

set(x, y [, notify]) or set(vec2 [, notify])

Sets the x and y coordinates of this vector. If false is passed for notify, none of the observers will be called.

returns: Vec2

zero()

Sets the x and y of this vector to 0

returns: Vec2

clone()

Returns a clone of this vector.

Note: this does not clone observers

returns: Vec2

negate([returnNew])

Negate the x and y coords of this vector. If returnNew is truthy, a new vector with the negated coordinates will be returned.

returns: Vec2

add(x, y [, returnNew]) or add(array, [, returnNew]) or add(vec2 [, returnNew])

Add the x and y to this vector's coordinates.

If returnNew is truthy, return a new vector containing the resulting coordinates. Otherwise apply them to this vector and return it.

returns: Vec2

subtract(x, y [, returnNew]) or subtract(array, [, returnNew]) or subtract(vec2 [, returnNew])

returns: Vec2

multiply(scalar [, returnNew]) or multiply(x, y [, returnNew]) or multiply(array, [, returnNew]) or multiply(vec2 [, returnNew])

Multiply this vectors components with the incoming, returning a clone if returnNew is truthy.

returns: Vec2

divide(scalar [, returnNew]) or divide(x, y [, returnNew]) or divide(array, [, returnNew]) or divide(vec2 [, returnNew])

Divide this vectors components by the incoming, returning a clone if returnNew is truthy.

note: this method will throw if you attempt to divide by zero or pass values that cause NaNs

returns: Vec2

rotate(radians [, inverse [, returnNew]])

Rotate this vector's cordinates around (0,0). If returnNew is specified, a new Vec2 will be created and populated with the result and returned. Otherwise the result is applied to this vector and this is returned.

inverse - inverts the direction of the rotation

returnNew - causes the result to be applied to a new Vec2, otherwise the result is applied to this

returns: Vec2

length()

Returns the length of this vector from (0,0)

returns: double

lengthSquared()

Returns the length of this vector prior to the Math.sqrt call.

This is usefull when you don't need to know the actual distance, but need a normalized value to compare with another Vec2#lengthSquared or similar.

returns: double

distance(vec2)

returns: the distance between this vector and the incoming

nearest(array)

returns: closest vector in array to this vector.

normalize([returnNew])

Normalizes this vector. If returnNew is truthy, a new vector populated with the normalized coordinates will be returned.

returns: Vec2

equal(vec2) or equal(x, y) or equal(array)

returns true if the incoming coordinates are the same as this vector's

returns: boolean

abs([returnNew])

Return a Vec2 that contains the absolute value of each of this vector's parts.

If returnNew is truthy, create a new Vec2 and return it. Otherwise apply the absolute values to to this.

returns: Vec2

min(vec)

Return a Vec2 consisting of the smallest values from this vector and the incoming

When returnNew is truthy, a new Vec2 will be returned otherwise the minimum values in either this or vec will be applied to this vector.

returns: Vec2

max(vec)

Return a Vec2 consisting of the largest values from this vector and the incoming

When returnNew is truthy, a new Vec2 will be returned otherwise the maximum values in either this or vec will be applied to this vector.

returns: Vec2

clamp(low, high [, returnNew])

Clamp the coordinates of this vector to the high/low of the incoming vec2s. If returnNew apply the result to the new vector and return. Otherwise apply to this vector.

returns: Vec2

lerp(vec, amount [, returnNew])

Perform linear interpolation between this vector and the incoming.

amount - the percentage along the path to place the vector

returnNew - if truthy, apply the result to a new vector and return it, otherwise return this

returns: Vec2

skew([returnNew])

Returns a vector set with the (-y,x) coordinates of this vector. If returnNew a new vector is created and the operation is applied to the new vector.

returns: Vec2

dot()

returns: double

perpDot()

returns: double

angleTo(vec)

returns the angle from this vector to the incoming.

returns: double

isPointOnLine(start, end)

where start and end are vec2-like (e.g. start.x and start.y)

returns: boolean

toArray()

returns: [x, y]

fromArray(array)

Applies the [0] to this.x and [1] to this.y

returns: Vec2

toJSON()

returns: { x: ..., y: ...}

toString()

returns: '(x, y)'

Install

Browser

<script type="text/javascript" src="https://raw.github.com/tmpvar/vec2.js/master/vec2.min.js"></script>
<script type="text/javascript">
   var v = new Vec2();
</script>

Node

install with npm

npm install vec2

and then require it!

var Vec2 = require('vec2');

License

MIT (see LICENSE.txt)