Unit-Bezier

A Combination of Mozilla and Chromium implementations of Bezier Curves used for animation interpolation for Javascript

Unit-Bezier takes optimizations from both Mozilla and Chromium timing function code and combines them into performant Javascript. It is compliant with both browsers' tests.

Getting Started

Download / Clone

Install with npm:

npm install Unit-Bezier

Clone the repo using Git:

git clone --bare https://github.com/jacobcpeters/Unit-Bezier.git

Alternatively you can download this repository.

Using Unit-Bezier

Use the 'new' operator to construct a new UnitBezier object for your function/module/class. The first parameter of the constructor is an array that contains the control points for the Bezier Curve [x1, y1, x2, y2]. The second parameter is the epsilon that controls the desired accuracy of the estimations.

var bezier = new UnitBezier(controlPoints, epsilon);

Easing Aliases

Easy to use aliases are available for common easing types in the UnitBezier.easings object.

var bezier = new UnitBezier(UnitBezier.easings.easeInOut, 0.005);

Table of available aliases:

Easing Name	Control Points
linear	[0.0, 0.0, 1.0, 1.0]
ease	[0.25, 0.1, 0.25, 1.0]
easeIn	[0.42, 0.0, 1.0, 1.0]
easeInOut	[0.42, 0.0, 0.58, 1.0]
easeOut	[0.0, 0.0, 0.58, 1.0]
easeInBack	[0.6, -0.28, 0.735, 0.045]
easeOutBack	[0.175, 0.885, 0.32, 1.275]
easeInOutBack	[0.680, -0.550, 0.265, 1.550]

Code example:

var bezier = new UnitBezier([0.0, 0.0, 1.0, 1.0], 0.000001), //linear Bezier Curve
    target = document.getElementById('animated-opacity'),
    animationLength = 1000, // 1000ms = 1s
    startTime = Date.now();
    
function animateOpacity() {
    var timeSinceAnimationStarted = Date.now() - startTime;
    
    target.style.opacity = 1 * bezier.calc(timeSinceAnimationStarted / animationLength);
    
    if(timeSinceAnimationStarted < animationLength) {
        requestAnimationFrame(animateOpacity);
    }
}
 
requestAnimationFrame(animateOpacity);

Feature requests

If Unit-Bezier doesn't support a feature you require, please put a request in the issues tracker.

License

© Jacob Peters, 2015. Licensed under an MIT license.