I thought I'd put up a short tutorial I made on multi-level parallax layers. This is for total, complete noobs, so if you already know about parallax, skip it. I made a tut with a few pics here:
[Parallax: Parallax is an apparent displacement or difference of orientation of an object viewed along two different lines of sight, and is measured by the angle or semi-angle of inclination between those two lines.]
Now if you are anything like me, that definition just went about as far over your head as a Saturn V rocket. In plainer english, parallax is 3D depth of movement. An object farther away moves at a different rate than an object closer to us.
Parallax in 2D games is a trick older than time. You use 3 (or more) backgrounds instead of 2. As the player moves through a level, each background layer scrolls at different speeds to mimic 3D movement. They don�t even have to be the correct speeds, the bottom layer just had to move at a slower rate than the upper layer. In Construct, this can easily be achieved with 3 or more layers. The beauty of Construct is that you are not limited by merely 3 layers. My space shooter�s first introductory level uses a layer for the player (hey, that rhymed!), 3 layers for parallax backgrounds, and a foundation layer to preserve our original scroll rate. So our layout is thus:
The key here is scroll rate. In Construct, go to the layers tab and create 5 layers.
Name them per the order listed above. Once you have them, set the �Scroll X Rate� and �Scroll Y Rate� for �background1' to 75%, set �background2' to 50%, and �background3' to 25%. Leave the �player� and �foundation� layers at 100%. To test this, add some sprites (any sprites) to each layer, add a test sprite to the �player� layer, and add an 8 direction behavior to it. Now test your game by hitting the computer monitor icon in the upper left, next to �File�. Boom, you can now see triple parallax at work. If you want even more depth, add more layers between �player� and �foundation�, simply adjust your scroll rates and you�re off to the races.
The general rule of thumb is the very bottom layer and the very top layer MUST have the same scroll rate for this to work. It�s that easy once you know the concept. Have fun!