As you can see there are still some excess drawing going on. Currently the drawing method checks if the tiles (x,y+1) and (x+1,y) are higher then it, and if it is don't draw the verts.
There still needs to be a way to check if a current vert is being covered, not the entire thing. Once this is established there will be an easy modification to do the same for the tiles.
Well, midterms start this week :(