Godot 4: Magnifying glass (fish eye) shader (tutorial)

Hi everyone! In this video, I would like to show how we can create a shader that works like a fish-eye camera or deforms part of the image using a magnifying glass. The shader will be fully configurable, so we'll be able to adjust the magnifying glass's radius, the level of distortion, or crop the edge to simulate looking through a peephole in a door.