Added a rain layer for atmosphere.

screens/primary.go

@@ -50,6 +50,11 @@ func NewPrimary() *Primary {
 	canvas.RegisterEvents(gamedata.GameEventFireball, p.EventHandlerFireball)
 	p.elements = append(p.elements, canvas)
 
+	//rainlayer
+	rain := gameelement.NewRainLayer(gamearea)
+	rain.Initialize()
+	p.elements = append(p.elements, rain)
+
 	//create foreground cloud layer
 	clouds := gameelement.NewCloudLayer(gamearea)
 	clouds.Initialize()