Recreating t3ssel8rs 3D pixel art terrain in Godot [NEED HELP]

For the past few years I've been enamored by T3ssel8r's 3D pixel art terrain system they made in Unity, of which you can see a demonstration of in this video (important to watch):

https://www.youtube.com/watch?v=mZjSmJ3dxHw

Ever since, I've been attempting to recreate it and my current attempt is in Godot, of which I've made a project of and uploaded to github(requires mono build of Godot, made in 4.2 but will probably work in any version from 4.0 to 4.2 and beyond): https://github.com/BradFitz66/PixelArtTerrain

My current algorithm works like this:

• Iterate through heightmap and for each distinct height (heightmap is quantized down to a certain amount of colors) create a new 'layer' (just 2D array of floats)

• Fill the layer with data (1s and 0s with 1 denoting a full cell and 0 denoting an empty cell)

• Run each layer through the marching square algorithm and generate a mesh

There's major issues with what I have currently. The terrain has holes all over the place. I'm not entirely sure how to solve that.

If anyone with a lot of experience in procedural mesh generation can give their input on this, that would be great!

I use Geometry3Sharp for mesh data (which is eventually converted to a godot-compatible mesh), this is because Geometry3Sharp comes with a bunch of stuff for extruding, simplification, etc. Read their github repo for more info.