Rename .env.example to .env and put proper values for both of its variables:
- PERF_CALC_PATH is going to be something like C:/osu-tools/PerformanceCalculator/bin/Release/net5.0/PerformanceCalculator.dll
- MAP_PATH is the path to the folder containing a bunch of {map_id}.osu files
Since PerformanceCalculator.dll won't print the stars for a map simulation by default, you will need to make a tiny adjustment to a file in the osu-tools repo. In osu-tools/PerformanceCalculator/Simulate/SimulateCommand.cs, add the following line to the other lines that look similar:
```
o["Stars"] = difficultyAttributes.StarRating;
```
Don't forget to recompile osu-tools via dotnet build -c Release after making the change.
Run cargo run --release. The program will use the PerformanceCalculator.dll to calculate the values and then store them in output.json.

Output format

The calculated values for each map for multiple different mod combinations will be stored in a JSON array. The array elements will be of the following form:

osu:

  {
      "mode": 0,
      "map_id": integer,
      "aim": double,
      "speed": double,
      "accuracy": double,
      "flashlight": double,
      "od": double,
      "ar": double,
      "mods": "HD, HR", // comma + whitespace separated string of mod abbreviations ("None" for nomod)
      "stars": double,
      "pp": double,
  }

taiko:

  {
      "mode": 1,
      "map_id": integer,
      "accuracy": double,
      "strain": double,
      "mods": "HD, HR", // comma + whitespace separated string of mod abbreviations ("None" for nomod)
      "stars": double,
      "pp": double,
  }

catch:

  {
      "mode": 2,
      "map_id": integer,
      "mods": "HD, HR", // comma + whitespace separated string of mod abbreviations ("None" for nomod)
      "stars": double,
      "pp": double,
  }

mania:

  {
      "mode": 3,
      "map_id": integer,
      "accuracy": double,
      "strain": double,
      "mods": "HD, HR", // comma + whitespace separated string of mod abbreviations ("None" for nomod)
      "stars": double,
      "pp": double,
  }