3.7.1 tween 怎么自定义 easing

[tell_me_why (天府三街黑铁V)]

const start = tween(element).by(0.25, { position: v3(0, this.moveOffset * dirModifier) }, { easing: ‘backIn’});

比如这个easing 能否用自定义CurveRange

[iwae (喵喵喵喵喵喵喵喵)]

可以自定义个(k)=>number

[tell_me_why (天府三街黑铁V)]

参数k是个啥啊