Drawing area of effect procedurally

Greatings. I have a fallowing problem: I need to draw an area of effect of a weapon. Infact it's not only an area of effect. It's something like an area of unit's vision combined with an effective distances of his weapons.

Green is a maximum accurecy, white is medium accurecy (it's infact not white but clear and green and red are infact semitransparent) and red is low accurecy. Could someone sugest me a module that implements this? Thank you!