I am working on a game helicopter ( http://i1-games.softpedia-static.com/screenshots/Copter_1.jpg ). When you touch the screen, you go up, otherwise you go down. Thus, you change the position of the sprite.
Now I need a trailpath for my sprite, anyone who has an idea how to do this? Here is an example of how it should look:

Tips for the center line are good enough. If you have an idea how to make a gradient, let me know!
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