<style>
body{
height: 600vh;
position: relative;
}
.abc{
width: 300px;
height: 300px;
background-image: url("https://picsum.photos/id/121/300/300");
position: fixed;
transition: all 0.2s;
left: 0px;
}
</style>
<body>
<div class="abc"></div>
</body>
<script>
$(function(){
$(window).scroll(function(){
let a = $(window).scrollTop();
let maxa = $(document).height()-$(window).height();
let halfa = maxa/2;
let ra;
if(a<=halfa){
ra = parseInt(a/halfa *150);
$(".abc").css("border-radius",ra+"px");
$(".abc").css("transform",'rotate(0deg)');
$(".abc").css("left","0px");
}
else{
ra = parseInt(a/halfa * 360-360);
ww = $(window).width()-$(".abc").width();
lt = parseInt(a/halfa *ww - ww);
$(".abc").css("border-radius",150+"px");
$(".abc").css("transform",'rotate(' + ra + 'deg)');
$(".abc").css("left",lt+"px");
}
console.log(ra+" "+a/halfa);
});
});
</script>