[QUOTE=Wigriff] That doesn't work for the same reason that my original couple of simple ideas didn't work: there might be 30 trees on the map, but there is really only 1 "tree." You have to use the UIDs to distinguish between different instances of trees in order to individualize each tree, or else the opacity will be set to 75% for each consecutive tree you walk into without it reverting to 100% until you aren't touching ANY trees.
You just end up with half of the trees being transparent that way. :) [/QUOTE]
Actually it should work, as each tick it sets every trees opacity to 100. After that it checks if player is overlapping any trees, and lowers their opacity. Don't see why it would not work :)