Yeah, I tried to copy / change the BlockGrass class to meet my needs, but came out a sickly green, I do have an overlay image, and when I place that as the TOP image, it's transparent, but it's the same shade of green as the biome.
Thanks for the top of the two-pass rendering, I'll have a look at it a.s.a.p.
Thanks! The two pass rendering worked a treat! Not 100% what I was after, but I got it working at least, now I do have at least one major issue, and one slight annoyance.
http://i.imgur.com/r3sJtYj.png
As you can see the biome colouring works a treat, but the block / item rendering in my hotbar is messed up, and I don't know how to fix that, and finally the slight annoyance, is that the bottom of the block is still that sickly green.
Here is the renderer class, the desire path class and the registry class
Thank you again for pointing me in this direction!