Shimmeringmoon

Arcaea screenshot analyzer!

This bot analyzes your Arcaea screenshots (both of your scores, and taken in the song-select menu), extracts score data from them, and keeps track of such score data in a database. This bot is still in development. Contact @prescientmoon on discord if you want to help out in any way.

Features

• song/chart info queries
• score queries (eg: listing your best score for a given chart)
• B30 (heck, even B300, if you so desire) rendering
• Multiple scoring systems to choose from (including sdvx like EX-scoring)
• Achievements (work in progress)
• Graph plotting (work in progress)

How does it work

• The bot uses poise in order to communicate with discord
• The bot renders images using my own custom bitmap renderer & layout system
• The bot recognises images using my own jacket recognition algorithm
• The bot reads text using my own OCR algorithm. The project started off by using Tesseract, although it was unreliable, and had big issues reading fonts with a lot of kerning (like Arcaea's song font for the bigrams 74 and 24). My implementation is much more accurate because it's much less general purpose, and uses knowledge of the font to achieve better results.

No neural-networks/machine-learning is used by this project. All image analysis is done using classical algorithms I came up with by glueing basic concepts together.

Running locally

The programs need (sometimes a subset of) the following environment variables in order to run:

SHIMMERING_DISCORD_TOKEN=yourtoken
SHIMMERING_DATA_DIR=shimmering/data
SHIMMERING_ASSET_DIR=shimmering/assets
SHIMMERING_CONFIG_DIR=shimmering/config
SHIMMERING_LOG_DIR=shimmering/logs

Binaries

The project currently exposes two binaries:

1. shimmering-discord-bot provides (as the name suggests) a discord bot exposing the shimmeringmoon functionality

2. shimmering-cli provides (again, as the name suggests) a command line interface for administration and debugging purposes:

   • The prepare-jackets command prepares the provided jackets for running the bot (see the section below for more details)
   • The analyse <...paths> command is a command-line version of the score magic discord command. This is useful for debugging things like the OCR implementation, without having to transmit files over the network.

Work in progress

These binaries are unstable at best, and broken at worst.

3. shimmering-server provides functionality over HTTP
4. shimmering-discord-presence is a client application that talks to shimmering-server in order to update your discord "currently playing", showing off the scores you are getting.

Fonts

The following fonts must be present in $SHIMMERING_FONTS_DIR:

Exo[wght].ttf
GeosansLight.ttf
Kazesawa-Bold.ttf
Kazesawa-Regular.ttf
unifont.otf

The shimmering-fonts derivation of the nix flake builds the aforementioned directory.

Assets

Most of the assets in this repo have been drawn by me. You need to bring in your own song jackets and place them at $SHIMMERING_ASSET_DIR/songs. This directory must contain a subdirectory for each song in the game, with each subdirectory containing a default jacket at base_256.jpg. Different files can be created to override the jacket for each difficulty. For more details, check out the implementation in ./src/arcaea/jacket.rs.

Additionally, you must place a custom b30 background at $SHIMMERING_ASSET_DIR/b30_background.jpg.

Caution

As far as I am concerned, the code in this repository does not violate the Arcaea terms of service in any way. Importing jackets that have been datamined/ripped out of the game is against the aforementioned TOS, and is highly discouraged.

After everything has been placed in the right directory, run shimmeringmoon-cli prepare-jackets to prepare everything. This will:

• Associate each asset with it's database ID
• Build out a recognition matrix (about 30\text{K}) for image recognition purposes. This file contains:
  • about 3 pixels worth of information for each jacket, stored together with the respective database ID
  • a projection matrix which transforms a 8 \times 8 downscaled vectorized version of an image (that's 192 dimensions — 64 \text{ pixels} \times 3 \text{ channels}) and projects it to a $10$-dimensional space (the matrix is built using truncated singular value decomposition).

Importing charts

The charts are stored in $SHIMMERING_CONFIG_DIR/charts.csv. This is a csv-version of Lumine's Arcaea song table (with permission). Importing song-data from any other source (such as datamined database files) will not only be more difficult for you (all the scripts I have written are built around the aforementioned spreadsheet), but is also against the Arcaea terms of service.

To add charts that have just been added to the CSV file into the database, run import-charts.py.

Testing

The project provides an always-growing automated test suite for it's core functionality. The command logic is written in terms of a generic MessagingContext trait, which allows running the commands in non-discord contexts. The technique employed is called "golden testing" (also known as "snapshot testing") — the output of each test is initially saved to disk (at test/commands). On subsequent runs, the output is compared to the existing files, with the test failing on mismatches. You can provide the SHIMMERING_TEST_REGEN=1 environment variable to override the existing output (make sure the changes are intended).

Each test saves it's output in a directory. Each file tracks the contents of a single response the bot produced during testing. This file contains everything from whether the response was a reply or not, to every field of every embed, to the hash of every attachment.

The screenshots used for testing are not available in this repository. Although thousands of Arcaea screenshots are posted to the internet on a daily basis, I do not want to risk any legal trouble. You need to therefore provide your own testing screenshots. The test suite expects the following files to be present in test/screenshots:

File	Description
alter_ego.jpg	a 9_926_250 score on ALTER EGO [ETR]
fracture_ray_ex.jpg	a 9_805_651 score on Fracture Ray [FTR]
fracture_ray_missed_ex.jpg	a 9_766_531 score on Fracture Ray [FTR]
antithese_74_kerning.jpg	a 9_983_744 score on Antithese [FTR]
genocider_24_kerning.jpg	a 9_724_775 score on GENOCIDER [FTR]

The hashes of the output images can often depend on the jacket images the tests were run with. This means you will likely have to regenerate the output locally in order to test with your own custom jackets.

Thanks

Many thanks go to:

• @.luminexus for providing the amazing Arcaea song table
• @siloricity for helping with development assets
• @black._heart_.sl for being the first person I discussed this idea extensively with
• @dyuan01 for discussing different scoring system ideas with me
• George Dragomir for, at my request, writing a new set of Tesseract bindings for the Rust programming language. The popular rust bindings for Tesseract are incomplete, unidiomatic, painful to use, easy to misuse, and leak copious amounts of memory. Please avoid them at all cost.
• The members of a certain small-scale Arcaea server for enduring my shimmeringmoon-related rambles :3