sankeyize.js

var sankeyIze = function(ox, oy, dx, dy) {
  var curve = ((dx-ox) * 0.25)
  var path = "";
  path += "M "+ ox + "," + oy;
  path += "Q " + (ox+curve) + "," + oy + " " + ((ox+dx)/2) +","+ ((oy+dy)/2);
  path += "Q " + (dx-curve) + "," + dy + " " + dx + "," + dy;
  return path;
};