# Vec2.js
[](http://ci.testling.com/tmpvar/vec2.js)
A generic library useful when you need to work with points/vectors in 2d space.
## Use
```javascript
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 `Infinity`and `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
```html
```
### Node
install with npm
npm install vec2
and then require it!
var Vec2 = require('vec2');
## License
MIT (see [LICENSE.txt](LICENSE.txt))