Hey! Thanks for checking out my mod.
This is a highly experimental, very messy, and very much still work-in-progress mod to bring Sonic Adventure gameplay to Sonic Generations, changing the relevant gameplay code to facilitate this. Included are custom objects that mimic the ones present in the original Emerald Coast level, as well as some other little additions and whatnot to get everything feeling just right--or just about right!
Being a work in progress, this is not the best reference for how to do something "correctly." This project contains a range of cleaned up code that's easy enough on the eyes, messy "gameplay code" that's intended to just get something working with comments and dead code paths at-the-ready to swap between at a moments notice, and straight up partially decompiled code both from Generations and SADX 2004. It's a bit of a frankenstein's mess.
So with that in mind, while this project is MIT licensed and I encourage the curious to take a look at how some things were done i.e. set objects, PLEASE do NOT just clone this code and copy/paste functions wholesale. That's not a great way to learn, first of all! But second, some of this is subject to change at any moment, including the gameplay code. Some of this is not very maintainable, while some of the code was made specifically for this project to get out the door for the Sonic Hacking Contest. There WILL be better resources for how to structure a project in the future, and right now you can find better projects like Skyth's mods, or BrianuuuSonic's 06DE (though some of what he does is a bit advanced still!). If you're looking to learn code best-practice, I recommend looking elsewhere. If you're here for a cursory glance at what makes Sonic Adventure tick, or how to get started making a custom gimmick for Generations, welcome! Tread with caution, cuz it's pretty messy around here haha.