Perform rounding to Precision in BindableNumber on decimal to avoid rounding error accumulation
#6249
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peppy
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Apr 16, 2024
bdach
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May 28, 2024
Compare: ppy#26616 This came up elsewhere, namely in ppy#28277 (comment). As it turns out, at least one beatmap among those whose scores had unexpected changes in total score, namely https://osu.ppy.sh/beatmapsets/971028#fruits/2062131, was using slider velocity multipliers that were not a multiple of 0.01 (the specific value used was 0.225x). This meant that due to the rounding applied to `SliderVelocityMultiplierBindable` via `Precision`, the raw value was being incorrectly rounded, resulting in incorrect conversion. The "direct" change that revealed this is most likely ppy/osu-framework#6249, by the virtue of shuffling the `BindableNumber` rounding code around and accidentally changing midpoint rounding semantics in the process. But it was not at fault here, as rounding was just as wrong before that change as after in this specific context.
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TextAdventurer12
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Jul 6, 2024
Compare: ppy#26616 This came up elsewhere, namely in ppy#28277 (comment). As it turns out, at least one beatmap among those whose scores had unexpected changes in total score, namely https://osu.ppy.sh/beatmapsets/971028#fruits/2062131, was using slider velocity multipliers that were not a multiple of 0.01 (the specific value used was 0.225x). This meant that due to the rounding applied to `SliderVelocityMultiplierBindable` via `Precision`, the raw value was being incorrectly rounded, resulting in incorrect conversion. The "direct" change that revealed this is most likely ppy/osu-framework#6249, by the virtue of shuffling the `BindableNumber` rounding code around and accidentally changing midpoint rounding semantics in the process. But it was not at fault here, as rounding was just as wrong before that change as after in this specific context.
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RFC. Closes ppy/osu#27847.
Didn't really benchmark this as I consider it a basic correctness issue, but will do on request. Game-side units tests pass.