rlbuddy can load custom maps now! Either you can download them and then import from a zip, or you can download them from bakkesplugins straight from the app!

Importing it from a file is relatively easy. I checked the code for Lethamyr’s custom map loader to see what exactly it did, and for Lethamyr maps it:

1. extracted the zip into a temp dir
2. read info.json, .udk, and preview.jpg
3. copied those into its own saved map directory

I knew Rust, being a low-level language would let me not have to extract the zip fully first. Additionally, Bakkesplugins maps don’t contain info.json or preview.jpg, they only contain a udk file, so I had to make sure it would work with that. So, the import code I wrote basically:

1. enumerates files in the zip
2. extracts info.json (if found) into a struct
3. copies *.upk into the target directory
4. copies *.jpg into the target directory/preview.jpg if it exists

It worked great. I made a really cool looking widget with stupid manual layouting behind it for map selection. First, it would add the preview image (or a black background if none). Then, it would get the screen rect of the image, and draw a semitransparent black background onto it (for contrast). Finally, it drew the actual contents in that screen rect. So, I got pretty-looking tiles with preview image backgrounds!

I also added a progress bar for import status. I benchmarked each main part of the import process and found that decompressing/extracting the upk file took around 2 seconds, for which the ui thread would be totally frozen (big nono)! So, I moved the work onto another thread, and also made it decompress/load in 100 total chunks, updating a progress bar each time.

I then moved on to the map downloader. Bakkesplugins doesn’t have an API, so it relies on scraping the website. I didn’t actually use any external crates for gathering information, though. I wrote a parser which takes a list of rules, each with a start and end search string, and looks for each of them in sequence till it fails to find a rule. I tried to make it completely zero-copy, but something it needed was to turn an [Option; N] into a Option<[T; N]> if every element was Some, but the only way I could figure out how to do that was with an iterator. It’s still really fast though. So, it parses search results, including map titles and urls straight out of the html string without needing an HTML parser or regex library.

Once it was able to load results from the search page, I went to sleep and came back today. Now I had to get it to actually download the ZIP files and preview images, and import them straight into the app. It first has to download/parse the plugin info page since the ZIP url isn’t available in the search results. Then, it requests the ZIP. I had some trouble with this, since I wanted to show a progress bar for the download status. I first tried a function from this gist, but it didn’t work. So, I made my own which used the same chunking strategy as the import status loader. Turns out, ureq blocks requests once they hit 10MB by default, which was probably why the gist version didn’t work. But, mine was faster anyways, so I kept it. It’s even cooler since I made it myself.

Then, I wired up a couple more commands to let it import straight from archive bytes instead of from a file path, and it finally loaded! Once that worked, I made it pass along the map title, author, and description as well. Then, I extended it to parse out the thumbnail image url and download that, then pass that along to the importer as well.

Anyways, that was super fun. I would add a lot more detail, but Stardance limits devlogs to 4000 characters and I’m approaching scarily close to that. I’m planning on just polishing the downloader interface a bit more, and then I’ll do some bugfixes for the next release. See ya!