I have 3 tiled images of some sort of galaxy/space in the background of a 2D Game: The first one has an alpha of 100%, the second an alpha of 80% and the last one has an alpha of 60%. I scroll the the one in the background slower than the other ones of course. classic parallax. In the foreground I have some particles flying towards the player to simulate some dust / stars flying by. (I know that stars don't fly by, but I think we all have seen this in a lot of games). But I can't quite achieve the depth effect I am looking for. I want it to look "deeper".
I did read something about using blending modes for the backgrounds, but that would require to render them as objects right?
So the question is: What is a good technique to do a scrolling parallax background in GameMaker?