Didn't know where else to ask so...

[1SDANi]

I've just finished following Alex_Stv's Voxel Tutorial series and started making my own non-cube block models. Everything was looking okay until I found that some chunks may be rendered over any non-cube block.

Here is an image of what I mean:

Notice how in the red tent, the clipping stops at a certain point. That is because that is the chunk boundary, and somehow only that chunk is affected.

Apparently it looks like it should if looked at from a particular angle:

Really annoying.

Here's a link to the code for the special blocks. I don't believe I've edited any other code:
https://drive.google.com/open?id=0B8GPmOdcLf_fLWZtUGdTaVZQMGs

Again, this is based on the Voxel Tutorial series by the same creator, but his website didn't say where I should ask such questions.