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Merge pull request #33969 from bdach/old-replays-or-something

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Fix very old lazer replays failing to decode
This commit is contained in:
Dean Herbert
2025-07-01 18:15:07 +09:00
committed by GitHub
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parent b3ba51d730 654faa553a
commit c845dd04d3
1 changed files with 17 additions and 1 deletions
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osu.Game/Scoring/Legacy/LegacyScoreDecoder.cs
+17 -1
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@@ -286,7 +286,23 @@ namespace osu.Game.Scoring.Legacy
// In mania, mouseX encodes the pressed keys in the lower 20 bits
int mouseXParseLimit = currentRuleset.RulesetInfo.OnlineID == 3 ? (1 << 20) - 1 : Parsing.MAX_COORDINATE_VALUE;
int diff = Parsing.ParseInt(split[0]);
// the legacy replay format as defined by stable expects frame delta times
// ('delta time' here meaning the amount of time between consecutive frames)
// to be integral and does not allow fractional values.
// one particular reason why this matters is that integral deltas
// avoid nasty floating point traps like accumulation error from summation or round-off error.
// however, there was a period in lazer's lifetime wherein lazer emitted replays
// with fractional (float) frame deltas, up until https://github.com/ppy/osu/pull/12583.
// despite the fact that gameplay mechanics changed multiple times since
// and the replay isn't going to play back anywhere near accurately anyway,
// no mistakes are ever forgiven, thus this attempts to parse the delta as an integer once,
// and if that fails, tries again as float.
// notably this cannot just be `(int)Parsing.ParseFloat(split[0])`, because that can lose information
// (`float` numbers have 24 bits of significand precision, which is not enough to accurately represent every possible value of `int`).
int diff;
if (!int.TryParse(split[0], out diff))
diff = (int)Math.Round(Parsing.ParseFloat(split[0]));
float mouseX = Parsing.ParseFloat(split[1], mouseXParseLimit);
float mouseY = Parsing.ParseFloat(split[2], Parsing.MAX_COORDINATE_VALUE);