This repo contains the source code for the demo from this article.
This demo uses raylib and raygui so you will need to first install those. Once installed, the demo itself is a pretty straight forward to make - just compile ranges.cpp.
I've included a basic Makefile which you can use if you are using raylib on Windows. You may need to edit the paths in the Makefile but assuming default installation locations you can just run Make.
If you are on Linux or another platform you will probably have to hack this Makefile a bit.
If you want to compile the web demo you will need to first install emscripten. Then you should be able to (on Windows) run emsdk_env followed by make PLATFORM=PLATFORM_WEB. You then need to run wasm-server.py, and from there will be able to access localhost:8080/ranges.html in your web browser which should contain the demo.