SOURCE

var w = 3909, h = 5120, size = 512, l = (w > h) ? w : h
console.log('l', l)

//z为缩放级别
var z = Math.ceil(Math.log(l / size) / Math.log(2))

console.log('zoom', z)
var count=0
cut(z,w, h)
for (var i = z - 1; i > 0; i--) {
 //   console.log(i)
    resize(i)
}

function cut(i,nw, nh) {
  //  console.log('cut')

    var xsize = Math.ceil(nw / size)
    var ysize = Math.ceil(nh / size)
    for (var x = 0; x < xsize; x++) {
        for (var y = 0; y < ysize; y++) {
            console.log(i,x,y)
            count++
        }

    }
}

function resize(i) {
    //根据缩放级别算出缩放倍数
    var scale = Math.pow(2, (z - i))
   // nw,nh为缩放后新的宽高
    var nw = w / scale, nh = h / scale
    console.log('resize', nw, nh)
    cut(i,nw,nh)
}
console.log('count',count)