This sample project showcases an implementation of dynamic split screen, also called Voronoi split screen, using the Godot engine.
This is now part of the Godot demo projects, under viewport/dynamic_split_screen and accessible soon from the Godot project manager, under the template tab.
A dynamic split screen system displays a single screen when the two players are close but a splitted view when they move apart.
The splitting line can take any angle depending on the players' position, so it won't be either vertical or horizontal.
This system was popularized by the Lego videogames.
Two cameras are placed inside two separate viewports and their texture, as well as some other parameters, are passed to a shader attached to a TextureRect filling the whole screen.
The SplitScreen shader, with the help of the CameraController script, chooses wich texture to display on each pixel to achieve the effect.
The cameras are placed on the segment joining the two players, either in the middle if they're close enough or at a fixed distance otherwise.
Open and launch the project inside the Godot engine and then you can use WASD keys to move the first player and IJKL keys to move the second one.
The Cameras node has parameters to tune the distance at which the screen splits and also the width and color of the splitting line.
An HTML5 export is testable here.