Jquery / Javascript不透明动画滚动 [英] Jquery/Javascript Opacity animation with scroll

问题描述

我想根据用户滚动更改对象的不透明度（并使过渡为动画）。
example（http://davegamache.com/）

I'm looking to change the opacity on an object (and have the transition be animated) based on a users scroll. example(http://davegamache.com/)

我在这里搜索了所有地方
，但它最终指向我waypoints插件（http://stackoverflow.com/questions/6316757/opacity-based-on-scroll-position）

I've searched everywhere like here, but it ends up pointing me to the waypoints plugin (http://stackoverflow.com/questions/6316757/opacity-based-on-scroll-position)

我已经实现了[waypoints] [1 ]插件，并且一旦它的高于100px，对象就会褪色。 [使用offet属性]但是想基本上控制对象的不透明度，并且动画是可见的，如上面的例子。

I've implemented the [waypoints][1] plugin and have the object fading once it's higher than 100px. [Using the offet attribute] but would like to basically control the opacity of an object and have the animation be visible like the above example.

这是我最后的手段。非常感谢任何帮助。

I've searched all over- this is my last resort. Any help is greatly appreciated.

推荐答案

工作示例，起点和终点：$ b​​ $ b http://jsfiddle.net/z7E9u/1/

working exemple with starting and ending point here: http://jsfiddle.net/z7E9u/1/

我复制粘贴基本代码

    var fadeStart=100 // 100px scroll or less will equiv to 1 opacity
    ,fadeUntil=200 // 200px scroll or more will equiv to 0 opacity
    ,fading = $('#fading')
;

$(window).bind('scroll', function(){
    var offset = $(document).scrollTop()
        ,opacity=0
    ;
    if( offset<=fadeStart ){
        opacity=1;
    }else if( offset<=fadeUntil ){
        opacity=1-offset/fadeUntil;
    }
    fading.css('opacity',opacity).html(opacity);
});

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