Dynamic shadow system

///Shadow
var max_length=96;

for (var i=0; i<max_length; i++)
{
  var ly=y+lengthdir_y(i,270);
  if (collision_point(x,ly,obj_wall,true,true))
    break;
}
shadow_size=(max_length/i)/4;
if (i<64)
{
draw_sprite_ext(sprite_index,image_index,x,ly-2,
shadow_size*image_xscale,-shadow_size/4,0,c_black,0.4)
}
draw_self();