The library manages to depth-sort correctly, even when using items of non-1x1 sizes. I took a look through the code but it's a big project to go through line by line!

There are some questions about the process such as:

1. How are the x, y, z values of each object defined? Are they the center points of the objects or something else?
2. I noticed that the IBounds defines the bounds of the object. If you were to visualise a cuboid of 40, 40, 90 in size, where would each of the IBounds metrics be?

I would like to know how as3isolib achieves this although I would also be happy with a generalised pseudo-code version.

At present I have a system that works 90% of the time but in cases of objects that are along the same horizontal line, the depth is calculated as the same value.

The depth calculation currently works like this:

x = object horizontal center point y = object vertical center point

originX and Y = the origin point relative to the object so if you want the origin to be the center, the value would be originX = 0.5, originY = 0.5. If you wanted the origin to be vertical center, horizontal far right of the object it would be originX = 1.0, originY = 0.5. The origin adjusts the position that the object is transformed from.

AABB_width = The bounding box width. AABB_height = The bounding box height.

depth = x + (AABB_width * originX) + y + (AABB_height * originY) - z;

This generates the same depth for all objects along the same horizontal x.