fading out tilemap layers

[danyburton]

hello friends, I have been trying to smoothly fade out certain layers of a tilemap, but have not been successful. I can get the tiles to dissapear, but I cannot get them to fade out.

Thankyou for any help

[danyburton]

don't worry, turns out I was trying to set the alpha to like -800 or something

 

[danyburton]

function* goSpooky(time)
{
  var totalTime = 0;
  while (totalTime < time)
  {
    totalTime += yield;
    var alpha = 1 - totalTime / time;
    if (alpha < 0) alpha = 0;
    for (var i = 1;i < state.tilemap.layers.length;i++)
    {
      state.tilemap.forEach
      (
        function(tile)
        {
          tile.alpha = alpha;
        },this,0,0,state.tilemap.width,state.tilemap.height,i
      );
      state.tilemap.layers[i].dirty = true;
    }
  }
}

here's my code if anyone ever desires it