Function updateSpringElement

docs/app/js/sanddance-app.js:87549–87555

(prev, cur, dest, damping, stiffness)

}
var EPSILON = 1e-5;
function updateSpringElement(prev, cur, dest, damping, stiffness) {
    var velocity = cur - prev;
    var delta = dest - cur;
    var spring = delta * stiffness;
    var damper = -velocity * damping;
    return spring + damper + velocity + cur;
}
function updateSpring(prev, cur, dest, damping, stiffness) {
    if (Array.isArray(dest)) {
        var next = [];