This is V2 of Fireflies, please add any suggestions you have to improve this!
I spent about 3 hours coding this, and for V2 I changed one of the blockshades I did previously, and used in my Road Trip SDS project. I think this adds to the ambiance, along with the curvy, more natural trees. I hope you enjoy it! You can go through and edit the pick random values in the code to change all of the firefly speeds, parallax speeds, firefly brightness, direction, etc.
