filtered-vector
===============
Applies cubic smoothing to a vector valued curve. This is useful for smoothing out inputs from the mouse or other input devices.

Example

``javascript
var now = require('right-now')
var filterVector = require('filtered-vector')
var smoothPosition = filterVector([256, 256])

var canvas = document.createElement('canvas')
canvas.width = 512
canvas.height = 512
document.body.appendChild(canvas)
var context = canvas.getContext('2d')

canvas.addEventListener('mousemove', function(ev) {
smoothPosition.push(now(), ev.x, ev.y)
})

function paint() {
requestAnimationFrame(paint)
var t = now()
context.fillStyle = 'rgba(0,0,0,1)'
context.fillRect(0,0,512,512)

context.strokeStyle = '#0f0'
context.lineWidth = 1
context.beginPath()
var x = smoothPosition.curve(t)
context.moveTo(x[0], x[1])
for(var i=0; i<2000; ++i) {
var y = smoothPosition.curve(Math.floor(t - i))
context.lineTo(y[0], y[1])
}
context.stroke()
}
paint()
`

Try out the demo in your browser.

Install

`
npm i filtered-vector
`

API

Constructor

#### var vec = require('filtered-vector')(initState[, initVelocity, initTime])
Creates a new smoothed vector with the given initial state, velocity and time.

* initState is the initial state of the vector
* initVelocity is the initial velocity of the vector
* initTime is the initial time of the vector

Returns A new smoothed vector valued curve

Methods

#### vec.curve(t)
Computes the value of the curve at time t

* t is the time parameter to sample the curve

Returns The value of the curve at time t

#### vec.dcurve(t)
Computes the derivative of the curve at time t

* t is the time parameter

Returns The derivative of the curve at time t

#### vec.bounds
A pair of arrays giving the upper and lower bounds on the constraints of the vector. Default is [-Infinity,-Infinity, ...] and [Infinity,Infinity,...]

#### vec.push(t, ...)
Adds a new data point onto the end of the curve

* t is the time the new data point was sampled
* ... are the components of the curve vector

#### vec.move(t, ...)
Incrementally moves the curve from the last sampled position by an offset. This is useful with input devices that emit relative motion (for example scrolling, key press events, pointer lock)

* t is the time at which the move event occured
* ... are the components of the relative motion

#### vec.set(t, ...)
Sets the state of the curve at time t

* t is the time parameter to sample
* ... are the components of the state

#### vec.jump(t, ...)
Sets the state of the vector at time t with no smoothing.

* t is the time parameter to sample
* ... are the components of the vector

#### vec.idle(t)
Adds a stationary data point to the curve (ie notify the curve that no input state has changed)

* t is the time at which the curve was idle

#### vec.flush(t)
Removes all samples in the buffer before time t

* t is the cutoff time

#### vec.lastT()

Returns The time of the last sample in the curve

#### vec.stable()

Returns true` is the vector is stationary as of the last event.

License

(c) 2015 Mikola Lysenko. MIT License