Ok, so I finally got around to creating a program that can write to MCA (region files). This was a LOT more difficult than the previous Minecraft level editor I made, as I had to deal with multiple layers (NBT recursive tags, ZLib compression, multiple calculations to get the chunk and block coordinates, and a sort of directory structure to hold everything). There are MANY places that this could have gone wrong, but at first it didn't seem that it did. I was able to load the r.0.0.mca file without any errors in the NBT Explorer software. So I thought everything was fine. But then when I copied this region file into the saves region subfolder of one of my gamesaves, and replaced the previous file of the same name, when I tried to play it in Minecraft, It refused to load it. The console showed a ton of errors. Here's a few lines of errors, just a sample of the full error set.
[03:49:04] [Server thread/ERROR]: Chunk file at 6,2 is missing level data, skipping
[03:49:04] [Server thread/ERROR]: Chunk file at 6,3 is missing level data, skipping
[03:49:04] [Server thread/ERROR]: Chunk file at 6,4 is missing level data, skipping
[03:49:04] [Server thread/ERROR]: Chunk file at 6,5 is missing level data, skipping
And here's a link to download the region file, so that if some uber Minecraft hacker/modder/toolmaker on here wants to take a look at the file and try to debug it, they will be able to do so. I hope that something in this file will indicate the exact nature of this problem, and that it will turn out to be a common one that most people have run into the first time they've tried to make a Minecraft level editor software, with a simple solution to fix it. This is the exact file, as output by my program, without having ever been played in Minecraft (and therefore has not been re-saved by the game). http://www.mediafire.com/download/39ua3wd1c1zquz4/r.0.0.mca
Never mind. I finally found that I was simply forgetting to put in the compound tag called "Level", after each unnamed compound tag that is the root tag for each chunk.
Why did this get moved to Mods Discussion? It is a question, involving a piece of software that I'm working on creating (not a mod to the Minecraft Jar or any other file in the game itself), in other words, a "tool". So the Minecraft tools section of this forum makes most sense.
[03:49:04] [Server thread/ERROR]: Chunk file at 6,2 is missing level data, skipping
[03:49:04] [Server thread/ERROR]: Chunk file at 6,3 is missing level data, skipping
[03:49:04] [Server thread/ERROR]: Chunk file at 6,4 is missing level data, skipping
[03:49:04] [Server thread/ERROR]: Chunk file at 6,5 is missing level data, skipping
And here's a link to download the region file, so that if some uber Minecraft hacker/modder/toolmaker on here wants to take a look at the file and try to debug it, they will be able to do so. I hope that something in this file will indicate the exact nature of this problem, and that it will turn out to be a common one that most people have run into the first time they've tried to make a Minecraft level editor software, with a simple solution to fix it. This is the exact file, as output by my program, without having ever been played in Minecraft (and therefore has not been re-saved by the game).
http://www.mediafire.com/download/39ua3wd1c1zquz4/r.0.0.mca