Showing highlighted silhouette of mesh ONLY when it is occluded

[ldogg]

Hi everybody, so i'm trying to create an online game using Babylon.js but have run into a problem thats got me a little stumped so hoping someone here would be willing to help me out. Please bear with me on this one, i'm a complete newbie with babylon as i've only every worked with THREE.js. Right now my game consists of a scene compromising of multiple meshes with multiple users represented as avatars (created from basic circle geometry for the moment) loaded into an environment. What I want to do is highlight the outline of these avatars ONLY when they are occluded by any other object, meaning that when they are not occluded they look normal with no highlight but when behind an object their highlighted silhouette can be seen by others (including yourself as you can see your own avatar). This is very akin to effects used in many other video games (see example below).

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Thus far, based on some googling and forum browsing (https://stackoverflow.com/questions/59807160/babylonjs-outline-through-walls & https://forum.babylonjs.com/t/highlight-through-objects/8002/4) I've figured out how to highlight the outline of objects using Babylon.HighlighLayer and I know that i can render objects above others via RenderingGroups but I can't seem to figure out how to use them in conjunction to create the effect I want. The best i've managed to do is get the highlighted avatar render above everything but I need just the silhouette not the entire mesh. I'm also constrained by the fact that my scene has many meshes in it that are loaded dynamically and i'm also trying to keep things as optimal as possible. Can't afford to use very computationally expensive procedures. 

Anybody know of the best way to approach this? Would greatly appreciate any advice or assistance you can provide.Thanks!