Sorting refers to the idea that certain objects get rendered in front of others in order to create the illusion of depth. Sorting objects in an isometric 3D engine is one of those pesky tasks that is taken for granted when it works like it's supposed to but sticks out like a sore thumb when it doesn't. The two furnaces below are sorting correctly. The one on the right appears to be "in front" of the one on the left, just as it is supposed to. Good deal.
BUT, if we move the right furnace back, flawed sorting rears its ugly head! The furnace looks like it has moved UP instead of back, which won't do at all.
