raphael-arrow.js

// single arrow at the end
Raphael.fn.arrow = function(x1, y1, x2, y2, size) {
  var angle = Raphael.angle(x1, y1, x2, y2);
  var a45   = Raphael.rad(angle-45);
  var a45m  = Raphael.rad(angle+45);
  var x2a = x2 + Math.cos(a45) * size;
  var y2a = y2 + Math.sin(a45) * size;
  var x2b = x2 + Math.cos(a45m) * size;
  var y2b = y2 + Math.sin(a45m) * size;
  return this.path(
    "M"+x1+" "+y1+"L"+x2+" "+y2+
    "M"+x2+" "+y2+"L"+x2a+" "+y2a+
    "M"+x2+" "+y2+"L"+x2b+" "+y2b
  );
};