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Code Issues Releases Wiki Activity

Add better commenting around legacy last tick edge case

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This commit is contained in:
Dean Herbert 2023-10-04 13:33:06 +09:00
parent 9361b1879c
commit cfb18e18c0
1 changed files with 14 additions and 5 deletions
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19
osu.Game/Rulesets/Objects/SliderEventGenerator.cs
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@ -88,18 +88,27 @@ namespace osu.Game.Rulesets.Objects
int finalSpanIndex = spanCount - 1;
double finalSpanStartTime = startTime + finalSpanIndex * spanDuration;
double finalSpanEndTime = Math.Max(startTime + totalDuration / 2, (finalSpanStartTime + spanDuration) + TAIL_LENIENCY);
double finalProgress = (finalSpanEndTime - finalSpanStartTime) / spanDuration;
if (spanCount % 2 == 0) finalProgress = 1 - finalProgress;
// Note that `finalSpanStartTime + spanDuration ≈ startTime + totalDuration`, but we write it like this to match floating point precision
// of stable.
//
// So thinking about this in a saner way, the time of the LegacyLastTick is
//
// `slider.StartTime + max(slider.Duration / 2, slider.Duration - 36)`
//
// As a slider gets shorter than 72 ms, the leniency offered falls below the 36 ms `TAIL_LENIENCY` constant.
double legacyLastTickTime = Math.Max(startTime + totalDuration / 2, (finalSpanStartTime + spanDuration) + TAIL_LENIENCY);
double legacyLastTickProgress = (legacyLastTickTime - finalSpanStartTime) / spanDuration;
if (spanCount % 2 == 0) legacyLastTickProgress = 1 - legacyLastTickProgress;
yield return new SliderEventDescriptor
{
Type = SliderEventType.LegacyLastTick,
SpanIndex = finalSpanIndex,
SpanStartTime = finalSpanStartTime,
Time = finalSpanEndTime,
PathProgress = finalProgress,
Time = legacyLastTickTime,
PathProgress = legacyLastTickProgress,
};
yield return new SliderEventDescriptor