Oh wow there is a way, but can I hide it?

Generating vertices at run-time and uploading the mesh to the CPU is expensive. It usually can't be done on complex meshes in real-time without incurring performance drops.

Shaders are likely the best way to go, unless you are only sporadically moving the objects in question (and their colliders), instead of moving them every frame.

For the record the system I have in place is not constantly running every frame or anything I'm just wondering if there's any possibility of simplifying the code a bit in Godot, the borders do expand though along with the colliders to handle the game logic if the radius increases. As for shaders I wasn't aware there would be a way of pulling off this effect without a mesh, the reason being is I wanted the influence circle to take into account the height of the terrain and hug it forming the clean borders you see in the topic.

I'd love to learn about any other potential options if there are any but I have done a LOT of research on this topic and this is unfortunately the best method I've found for achieving the effect, at least in 3D. I'm surprised how little border effects are discussed these days given how awesome they can make games look. I'm also a big fan of the elite dangerous influence map.

10 days later

https://godotshaders.com/shader/influence-area-displaying-shader/

Interesting! I'm doing a bit of a necro on this but people will find it useful, I found a shader somebody created that does exactly the same as the method that I posted up initially. The only issue is can I make this more 3D possibly? I'd like to have the shader go vertical, other than that the behaviour is very similar and it seems to be pretty efficient just using purely shader rather than any mesh generation.

I may still end up using my mesh generation method for the sake of customisability depending on what information I can find on this, we'll see though.

6 months later