shaders – How do I render zones like Cities Skylines district device?

I’m making an attempt to implement a zoning system just like the district device in Cities Skylines (see screenshot under). The participant is ready to attract/modify/erase zones with a brush device. Internally, I signify every zone with a closed chain of vertices equally spaced out. I’m new to laptop graphics and recreation dev normally. I recognize any pointer! 🙂

1. How do I render the semi-transparent white overlay for every zone as within the screenshot? My present resolution entails a dynamically generated mesh, with a semi-transparent materials. Is there a greater manner?
2. How do I render the white daring edge of every zone?
3. How do I render the “sticki-ness” between the perimeters? As in, when two edges get too shut, the sport fills the tiny area between them with white coloration as properly.

I am utilizing Unreal 5 if that issues.