The other issue I am having with making my player interact correctly with trees is a z order problem, I believe. I have browsed the forums looking for a solution, but so far I haven't found any.
Basically, I want the player sprite to look like he is standing in front of a tree if he logically SHOULD be standing "in front" of a tree, and I want him standing behind a tree if he should be standing "behind" a tree. So far I have him permanently z-ordered behind the trees.
This is a test level with some placeholder graphics for the UI and no animation, so please excuse the awful presentation. I just want to show an example of how it is currently working.
We are making a tower defense game along the lines of Pixel Junk Monsters if anyone here has played it on PS3. If you watch some PJM gameplay footage you will see how their player interacts with trees. We aren't cloning the game, but we pretty much cloned their 1st level because we figured if we can make a PJM level first with all the core functionality, we can just adjust things from there.