When reviewing some trees from BigTiger (See attached mod) I noticed a bug with our engine where the entities using alpha would not be sorted according to depth, which would make the field go in front of the trees for instance

You can load the map test.xml

and see the bug. Notice than reloading the map a second time fixes the bug, but it's always broken the first time.

Notice the bug never happens with the patch.

Check the performance impact. I couldn't notice any but I have a pretty good machine.