So I want to do marching cubes in 3D with the grid of points moved around by depth. So we have XYZ and screen x and screen y.

We're going to need to interpolate edge midpoints for each cube and sloppy duplication will be okay for the first pass. We'll just need to identify edges with endpts inside or outside the surface, draw those midpts, then keep track of them in each cube and build as many triangle faces as needed to map the surfaces