The Meaning of Life, the Universe, and Everything.
I think I have calculate that a wolf's aggro range towards sheeps or skeletons is approximately 16 blocks (somewhere between 15 and 17) in a straight line.
Oddly, at some point on a multiplayer server, when testing this with surface, I need to have the wolf at the opposite corner of a 16x16 square to keep it quiet (testing with a sheep).
It seemed me that a wolve can get angry at skeleton even when they're sperated by wall, line of sight or not ... except today still on multiplayer server, I had a wolf that kept quiet at approx. 6 blocks from a skeleton, separated by a wall ... I wonder if it may have got something to do with the fact that this skeleton was completele encased in blocks? Name tagged? The tag was "Dinnerbone"? Yes the server as a claim system which may proct tagged mobs?
Another thing I observed is a wolf located at approx 4 blocks south of sheeps, the sheeps being on the surface and the wolf underground. This wolf doesn't get angry.
So what's the effect of altitude on wolf's aggro range? Am I wrong regarding line of sight have no effect? Any more precisions/construtive corrections welcome.