Having upgraded to 1.16, new chunks that are generated in the nether often don't blend with the old chunks (new chunks often appear as cross-sections next to old chunks), so I would like to regenerate all my old chunks.
However, I have already built an awful lot in the nether - a huge central hub, multiple farms and a simple but lengthy network of tunnels of 5x5 width/height from -1000,-1000 to 1000 1000.
I would like to start a fresh new nether world, regenerate a 2000x2000 region, and then copy over only these specific regions that I've built on.
I've worked out I would only need to copy 8 box regions and 2 diagonal box regions and noted these exact co-ordinates.
Ignoring chests and such, you can consider each block is just an integer / string in a 3D array, the task at hand should be very simple. I could easily write my own mod that exports these regions to a JSON file, and then imports them, but I figured there must be a command line tool or pre-existing mod to save me the effort.
The Meaning of Life, the Universe, and Everything.
you can try to place the files of the chunks you have builded in from the old nether folder to the new nether folder it would mean though that you will have to track down the chunks 1 by 1 but if you get all the numbers of them from the ingame then it's a matter of minutes to swap the files in the nether folders just make sure to do back ups from the world before