There is some code [0] for generation of coastal lines in cartographic maps (text in french, code in JavaScript). It's kind of similar. The blog post [1] about

There is some code [0] for generation of coastal lines in cartographic maps (text in french, code in JavaScript). It's kind of similar. The blog post [1] about fiziko describes how it calculates parallel bezier curves using line intersection and curves of varying thinkness. The code about the coastal lines also uses a similar technique and describes how to get the result step by step. [0] https://observablehq.com/@linard-y/chemin-decale-offset-paths https://observablehq.com/@linard-y/chemin-decale-offset-path... [1] https://habr.com/en/post/454376/ https://habr.com/en/post/454376/