Question : Set alpha to part of a Movie Clip

If I have a MovieClip called square_mc which consists of a square is it posible to set its alpha to .5 but just in a specific part of square_mc? for example if I have a movie clip called circle_mc could I set the alpha of square_mc to .5 but just in the center of the movie clip and as big as circle_mc so that it looks like a square with a circle in the center because the alpha of the circle is less?

Answer : Set alpha to part of a Movie Clip

you're in a bit of a predicament I'd say, as you can easily draw basic shapes with the drawing api and control the colour/alpha with that but to do terrains with code might be another issue of note.
I misunderstood your original post I thought you were drawing the items on stage.

good luck.