2d Terrain/Object Detection

well, I'm working on a 2d top-down game for my cs class, and am currently setting up the terrain. However, I've run into a problem. To spare you a confusing explanation, I've taken the liberty of using ASCII to draw a diagram. :

		
		
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The obvious problem is determining when a) the vehicle is beneath the bridge/object - the vehicle drawn first, then the bridge, and when it is it is over it (i.e. flying) - the bridge drawn first, vehicle last. The best I could think of was to make an ordered list of objects to draw (sorted by [y] value - those past a certain [y] are simply not drawn, but are included because collisions have to be checked for) to make it more efficient and to keep the drawing centralized. I'm using java with swing [straight up], so I need to minimize the drawing calls. Then use two [for] loops, checking for collisions and then switching the position of the two objects if one needs to be infront. that seems a little inefficient, though, and error prone. does anyone have a better thought/idea/solution ? any help is appreciated. [Edited by - stormrunner on October 29, 2004 6:05:18 PM]