In games or animations, there are many moving objects which can move them from point A to B linearly, but after applying an easing, or easing function, it can make it look more natural. An easing function says an animation of how to progress. In this way, a straight motion can take an interesting shape.
Easing functions specify the rate of change of a parameter over time. It is whose equations which make something move slowly at the start and speed up, or slow down near the end. The most common set of easing equations come from Robert Penner’s book and webpage.
The easeInOutBack() method is used for the effect of backwards easing in and out the object it is used on.
Syntax:
easeInOutBack(t, b, c, d)
Parameters: This method accepts four parameters as mentioned above and described below:
- t: This parameter holds the specified time when animation will start. For example, if value of t is 0, it means animation is just started.
- b: This parameter holds the specified starting position of the object on x-axis. For example, if value of b is 10, it means the starting position of the objects on x-coordinate is 10.
- c: This parameter holds the specified change in value for the object. For example, if value of c is 30, it means, the object has to move 30 to the right, ending at 40.
- d: This parameter holds the specified duration of the whole process. For example, if the value of d is 2, it means, the object has 2 second to perform this motion from 10 to 40.
Return Value: This method returns the eased position of the object i.e., the position of the object at a specific time.
Example 1:
<html>
<head>
<!-- Adding the FabricJS library -->
<script src=
</script>
</head>
<body>
<script type="text/javascript">
// The easeInOutBack() function
function easeInOutBack (t, b, c, d) {
if (s == undefined) s = 1.70158;
if ((t /= d / 2) < 1)
return c / 2 *
(t * t * (((s *= (1.525)) + 1)
* t - s)) + b;
return c / 2 *
((t -= 2) * t *
(((s *= (1.525)) + 1) * t
+ s) + 2) + b;
}
// Calling the easeInOutBack() function over
// the specified parameter values
console.log(
fabric.util.ease.easeInOutBack(1, 2, 3, 4)
);
</script> </body>
</html>
|
Output:
1.70095446875
Example 2:
<html>
<head>
<!-- Adding the FabricJS library -->
<script src=
</script>
</head>
<body>
<script type="text/javascript">
// Initializing the parameters with its values
var t = 5;
var b = 10;
var c = 40;
var d = 12;
// Calling the easeInOutBack() function over
// the specified parameter values
console.log(
fabric.util.ease.easeInOutBack(t, b, c, d)
);
</script>
</body>
</html>
|
Output:
15.567339120370374