Partially addresses https://github.com/ppy/osu/discussions/26416
As pointed out in the discussion thread above, the total score
conversion process for mania was using accuracy directly from the
replay. In mania accuracy is calculated differently in score V1 than in
score V2, which meant that scores coming from stable were treated more
favourably (due to weighting GREAT and PERFECT equally).
To fix, recompute accuracy locally and use that for the accuracy
portion.
Note that this will still not be (and cannot be made) 100% accurate, as
in stable score V2, as well as in lazer, hold notes are *two*
judgements, not one as in stable score V1, meaning that full and correct
score statistics are not available without playing back the replay.
The effects of the change can be previewed on the following spreadsheet:
https://docs.google.com/spreadsheets/d/1wxD4UwLjwcr7n9y5Yq7EN0lgiLBN93kpd4gBnAlG-E0/edit#gid=1711190356
Top 5 changed scores with replays:
| score | master | this PR | replay |
| :------------------------------------------------------------------------------------------------------------------------------- | ------: | ------: | ------: |
| [Outlasted on Uwa!! So Holiday by toby fox [[4K] easy] (0.71\*)](https://osu.ppy.sh/scores/mania/460404716) | 935,917 | 927,269 | 920,579 |
| [ag0 on Emotional Uplifting Orchestral by bradbreeck [[4K] Rocket's Normal] (0.76\*)](https://osu.ppy.sh/scores/mania/453133066) | 921,636 | 913,535 | 875,549 |
| [rlarkgus on Zen Zen Zense by Gom (HoneyWorks) [[5K] Normal] (1.68\*)](https://osu.ppy.sh/scores/mania/458368312) | 934,340 | 926,787 | 918,855 |
| [YuJJun on Harumachi Clover by R3 Music Box [4K Catastrophe] (1.80\*)](https://osu.ppy.sh/scores/mania/548215786) | 918,606 | 911,111 | 885,454 |
| [Fritte on 45-byou by respon feat. Hatsune Miku & Megpoid [[5K] Normal] (1.52\*)](https://osu.ppy.sh/scores/mania/516079410) | 900,024 | 892,569 | 907,456 |
Co-authored-by: Zyf <zyfarok@gmail.com>
Closes https://github.com/ppy/osu/issues/25860
Users reported that some stable scores would convert to large negative
total scores in lazer after the introduction of combo exponent. Those
large negative total scores were actually mangled NaNs.
The root cause of this was the following calculation going below zero
unexpectedly:
8e8d9b2cd9/osu.Game/Database/StandardisedScoreMigrationTools.cs (L323)
which then propagates negative numbers onward until
8e8d9b2cd9/osu.Game/Database/StandardisedScoreMigrationTools.cs (L337)
which yields a NaN due to attempting to take the square root of a
negative number.
To fix, clamp `comboPortionInScoreV1` to sane limits: to
`comboPortionFromLongestComboInScoreV1` from below, and to
`maximumAchievableComboPortionInScoreV1` from above. This is a less
direct fix than perhaps imagined, but it seems like a better one as it
will also affect the calculation of both the lower and the upper
estimate of the score.
Causes several knock-on inspections in `OsuGame` et al. Probably best
addressed in a separate pass, because treatment is mixed at best (some
places nullcheck, some expect non-null).
