# Ease

A generic implementation of standard easing functions for use in animation or
robotics.

For examples of "standard" easing algorithms (in this case used in CSS
animations) take a look at [easings.net](http://easings.net)

## Installation

[Available in Hex](https://hex.pm/packages/ease), the package can be installed
by adding `ease` to your list of dependencies in `mix.exs`:

```elixir
def deps do
  [{:ease, "~> 0.1.0"}]
end
```

Documentation can be found at [https://hexdocs.pm/ease](https://hexdocs.pm/ease).

## Usage

You can use an easing function directly from within your own loop, provided
that you can supply the four arguments needed;

* `current_time` - the elapsed "time" in the loop, ie if your `duration` is
  ten, and you want to find the position for half way through the duration
  then you set it to `5`. Units are arbitrary (steps, ms, whatever).
* `start_value` - the initial value or position at `current_time` of zero.
* `change_in_value`- how much the `start_value` should be changed by the end
   of the animation, ie the expected final value minus the `start_value`.
* `duration` - the duration of the animation, in the same units as `current_time`.

Given a quadratic ease-in of `1..10`, over 1 unit of time, where would we be
when half-way through:

    iex> Ease.ease_in_quad(0.5, 1, 10, 1)
    3.25

Plot the `{x, y}` positions for a circular ease-in:

    iex> ys = 1..10
    ...> xs = Ease.map(ys, :ease_in_circular)
    ...> Enum.zip(xs, ys)
    [{1.0, 1}, {1.0557280900008417, 2}, {1.2250356126078779, 3},
     {1.5147186257614298, 4}, {1.9377422517014504, 5}, {2.5166852264521173, 6},
     {3.291796067500631, 7}, {4.34314575050762, 8}, {5.876894374382339, 9},
     {10.0, 10}]

# License

Source code is licensed under the terms of the MIT license, the text of which
is included in the `LICENSE` file in this distribution.