The shader itself is where the bulk of the change has gone, and I will try my best to explain every step of the process...
our constants and variables are set, most significant this time around are coordL coordR (since the different texture resources are loaded onto different fields of the texture page we're drawing from, coordL is the left half, and coordR is the right half). also important is intLeap and floatLeap, which will be used for traversing for loops later on when we do ray tracing.