[英]JavaScript animation with easing
I'm trying to build a slider module with JavaScript. 我正在尝试使用JavaScript构建滑块模块。 Everything works, but the animation is linear, and doesn't feel smooth or natural.
一切正常,但动画是线性的,并且感觉不流畅或自然。 I had thought of hooking up an easing equation, but I'm not sure where it goes.
我原本想挂钩一个宽松的方程式,但我不确定它的去向。
Here's the animation function I borrowed from here : 这是我从这里借来的动画功能:
function animate(elem, style, unit, from, to, time) {
if (!elem) return;
var start = new Date().getTime(),
timer = setInterval(function() {
var step = Math.min(1,(new Date().getTime()-start)/time);
elem.style[style] = (from+step*(to-from))+unit;
if (step == 1) clearInterval(timer);
},25);
elem.style[style] = from+unit;
}
And an easing function from here : 还有一个从这里开始的缓动功能:
/**
* @param {Number} t The current time
* @param {Number} b The start value
* @param {Number} c The change in value
* @param {Number} d The duration time
*/
function easeInCubic(t, b, c, d) {
t /= d;
return c*t*t*t + b;
}
I tried just passing in the values I already have like this: 我尝试只传递已经具有的值:
elem.style[style] = easeInCubic(start, from, to, time) + unit;
But clearly, that's wrong (I'm not amazing at maths, and I'm admittedly just guessing). 但是很显然,这是错误的(我在数学上并不令人惊讶,并且我只能猜测)。
How do I join the two together? 如何将两者结合在一起?
your approach is ok, you just used wrong parameters. 您的方法还可以,只是使用了错误的参数。 as it says, t is current time and d is overall animation time
就像它说的那样,t是当前时间,d是整体动画时间
function animate(elem, style, unit, from, to, time) {
if (!elem) return;
var start = new Date().getTime(),
timer = setInterval(function() {
var step = Math.min(1,(new Date().getTime()-start)/time);
elem.style[style] = easeInCubic(step*time, from,step*(to-from), time)+unit;
if (step == 1) clearInterval(timer);
},25);
elem.style[style] = from+unit;
}
t
is the current time, or more accurately the elapsed time. t
是当前时间,或更准确地说是经过的时间。 In your case new Date().getTime() - start
在您的情况下,
new Date().getTime() - start
c
is the difference between start and end, in your case from - to
. c
是开始和结束之间的差,在您的情况下from - to
。
var elapsedTime = new Date().getTime() - start;
elem.style[style] = easeInCubic(elapsedTime, from, to - from, time) + unit;
if (elapsedTime >= time) clearInterval(timer);
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