Ignoring blocking tiles?

[maximus_asinus]

PHP Code:

function onCreated() {
  setshape2(10,10,{
    11,11,11,11,11,11,11,11,11,11,
    11,11,11,11,11,11,11,11,11,11,
    11,11,11,11,11,11,11,11,11,11,
    11,11,11,11,11,11,11,11,11,11,
    11,11,11,11,11,11,11,11,11,11,
    11,11,11,11,11,11,11,11,11,11,
    11,11,11,11,11,11,11,11,11,11,
    11,11,11,11,11,11,11,11,11,11,
    11,11,11,11,11,11,11,11,11,11,
    11,11,11,11,11,11,11,11,11,11,
  });
  showpoly(200,{30,30,40,30,40,40,30,40});
  with (findimg(200)) {
    red = 0;
    green = 0;
    blue = 1;
    alpha = 0.75;
    layer = 0;
  }
} 


I'm trying to emulate the rising water from Link to the Past. This method gives me the desired effect visually, but I still need to override the blocking tiles in the affected area to turn them into swimming tiles.



My best method would be to draw the castle tiles on another layer, put non-blocking tiles underneath, and then use setshape to block the player when the water is drained. I'm just wondering if there is a better way.