[Enhancement Req] Consider limiting rendering area when blocks are in front of mob fan

[JustJinxed]

I've overlooked this for awhile, but it came up in a recent Direwolf20 video. Seems the mob fan height and width rendering when showing the area, aren't impacted by a block in front of the fan, but the distance is. Is this intentional? And if so, can we maybe add a little something in the UI letting the player know when fan is blocked for distance, so newbies don't confuse it as not working?