Shader source exploration, info requested to finish series (C++)

[ceedj]

Hi folks, I'm CJ, creator/coder of the PEDS webseries. Yes, THAT. Long story short, life happened, I want to finish this. I've been updating my filming mod and cleaning up the mess of code I've built over the last 10 years or so (omg LAMBDAS? I've been under a rock!) Anyway, for the finale, I'd like (not-really-but-maybe-spoilers?) a glow outline around two of my characters. I've seen some screenshots that come pretty close to what I'd like, so with an updated compiler in hand, I'd like to give it a shot. I don't really have any relevant code yet, so here's a screenshot of some code that I've been working on. This is in a blank file (I've been stripping my experiments from the mod and giving them their own code space) so please ignore the Intellisense squigglies. 

So, can anyone shed some light on where in the source I can start exploring this? I learned 3 different languages to get this going almost 15 years ago, what's one more?

Thanks for looking!

EDIT/PS: I can likely do this in post (After Effects) by rotoscoping and some creative masks, but I'm really aiming to get as much in-game as I can, I've put together several new animations as well, and used a few community updates to my particles. Although motion tracking is neat, getting in-game fx from any angle I want is neater. 

Edited February 10, 2019 by ceedj