Actionscript3 alpha masking?

Question

I was trying to apply a spotlight effect on a google map application. Specifically, I draw a circle that follows the mouse and set it as a mask over the map. The problem is

Answer 1

Another option is to use blendModes (it could be a bit more cpu expensive in some cases, but you can do a lot more like gradients and stuff). You need a hierachy like this:

parent clip (blendmode="layer")
   -mask with different alpha values (blendmode="alpha")
   -background image (blendmode="normal")

In your case, you would have your map as the background image. Then, inside the mask clip (do not set it as mask) put a 10% alpha shape covering the entire background and a circular shape with 100% alpha that follows your mouse... you can even put some blur to the circular shape, so you get a nice gradient...

I did something very similar some time ago, so I uploaded an early test here (fla) if you want to have a look :)