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Fix slider event generator incorrectly not generating repeats when tick distance is zero

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RFC. This closes https://github.com/ppy/osu/issues/31186.

To explain why: The issue occurs on
https://osu.ppy.sh/beatmapsets/594828#osu/1258033, specifically on the
slider at time 128604. The failure site is

	fa0d2f4af2/osu.Game.Rulesets.Osu/Edit/Blueprints/Sliders/SliderCircleOverlay.cs (L65-L66)

wherein `LastRepeat` is `null`, even though the slider's `RepeatCount`
is 1 and thus `SpanCount` is 2.

In this case, `SliderEventGenerator` is given a non-zero `tickDistance`
but a zero `length`. The former is clamped to the latter:

	fa0d2f4af2/osu.Game/Rulesets/Objects/SliderEventGenerator.cs (L34)

Because of this, a whole block of code pertaining to tick generation
gets turned off, because of zero tick spacing - however, that block also
includes within it *repeat* generation, for seemingly very little reason
whatsoever:

	fa0d2f4af2/osu.Game/Rulesets/Objects/SliderEventGenerator.cs (L47-L77)

While a zero tick distance would indeed cause `generateTicks()` to loop
forever, it should have absolutely no effect on repeats.

While this *is* ultimately an aspire-tier bug caused by people pushing
things to limits, I do believe that in this case a fix is warranted
because of how hard the current behaviour violates invariants. I do not
like the possibility of having a slider with multiple spans and no
repeats.
This commit is contained in:
Bartłomiej Dach 2024-12-27 12:25:51 +01:00
parent ecf64dfc57
commit e7225399a2
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1 changed files with 15 additions and 15 deletions
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30
osu.Game/Rulesets/Objects/SliderEventGenerator.cs
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@ -44,13 +44,13 @@ namespace osu.Game.Rulesets.Objects
PathProgress = 0,
};
if (tickDistance != 0)
for (int span = 0; span < spanCount; span++)
{
for (int span = 0; span < spanCount; span++)
{
double spanStartTime = startTime + span * spanDuration;
bool reversed = span % 2 == 1;
double spanStartTime = startTime + span * spanDuration;
bool reversed = span % 2 == 1;
if (tickDistance != 0)
{
var ticks = generateTicks(span, spanStartTime, spanDuration, reversed, length, tickDistance, minDistanceFromEnd, cancellationToken);
if (reversed)
@ -61,18 +61,18 @@ namespace osu.Game.Rulesets.Objects
foreach (var e in ticks)
yield return e;
}
if (span < spanCount - 1)
if (span < spanCount - 1)
{
yield return new SliderEventDescriptor
{
yield return new SliderEventDescriptor
{
Type = SliderEventType.Repeat,
SpanIndex = span,
SpanStartTime = startTime + span * spanDuration,
Time = spanStartTime + spanDuration,
PathProgress = (span + 1) % 2,
};
}
Type = SliderEventType.Repeat,
SpanIndex = span,
SpanStartTime = startTime + span * spanDuration,
Time = spanStartTime + spanDuration,
PathProgress = (span + 1) % 2,
};
}
}