// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.
using System;
using System.Collections.Generic;
using System.Linq;
using osu.Framework.Graphics;
using osu.Game.Beatmaps;
using osu.Game.Rulesets.Objects;
using osu.Game.Rulesets.Objects.Types;
using osu.Game.Rulesets.Osu.Objects;
using osuTK;
namespace osu.Game.Rulesets.Osu.Beatmaps
{
public class OsuBeatmapProcessor : BeatmapProcessor
{
private const int stack_distance = 3;
public OsuBeatmapProcessor(IBeatmap beatmap)
: base(beatmap)
{
}
public override void PreProcess()
{
IHasComboInformation? lastObj = null;
// For sanity, ensures that both the first hitobject and the first hitobject after a spinner start a new combo.
// This is normally enforced by the legacy decoder, but is not enforced by the editor.
foreach (var obj in Beatmap.HitObjects.OfType<IHasComboInformation>())
{
if (obj is not Spinner && (lastObj == null || lastObj is Spinner))
obj.NewCombo = true;
lastObj = obj;
}
base.PreProcess();
}
public override void PostProcess()
{
base.PostProcess();
ApplyStacking(Beatmap);
}
internal static void ApplyStacking(IBeatmap beatmap)
{
var hitObjects = beatmap.HitObjects as List<OsuHitObject> ?? beatmap.HitObjects.OfType<OsuHitObject>().ToList();
if (hitObjects.Count > 0)
{
// Reset stacking
foreach (var h in hitObjects)
h.StackHeight = 0;
if (beatmap.BeatmapInfo.BeatmapVersion >= 6)
applyStacking(beatmap.BeatmapInfo, hitObjects, 0, hitObjects.Count - 1);
else
applyStackingOld(beatmap.BeatmapInfo, hitObjects);
}
}
private static void applyStacking(BeatmapInfo beatmapInfo, List<OsuHitObject> hitObjects, int startIndex, int endIndex)
{
ArgumentOutOfRangeException.ThrowIfGreaterThan(startIndex, endIndex);
ArgumentOutOfRangeException.ThrowIfNegative(startIndex);
ArgumentOutOfRangeException.ThrowIfNegative(endIndex);
int extendedEndIndex = endIndex;
if (endIndex < hitObjects.Count - 1)
{
// Extend the end index to include objects they are stacked on
for (int i = endIndex; i >= startIndex; i--)
{
int stackBaseIndex = i;
for (int n = stackBaseIndex + 1; n < hitObjects.Count; n++)
{
OsuHitObject stackBaseObject = hitObjects[stackBaseIndex];
if (stackBaseObject is Spinner) break;
OsuHitObject objectN = hitObjects[n];
if (objectN is Spinner)
continue;
double endTime = stackBaseObject.GetEndTime();
double stackThreshold = objectN.TimePreempt * beatmapInfo.StackLeniency;
if (objectN.StartTime - endTime > stackThreshold)
// We are no longer within stacking range of the next object.
break;
if (Vector2Extensions.Distance(stackBaseObject.Position, objectN.Position) < stack_distance
|| (stackBaseObject is Slider && Vector2Extensions.Distance(stackBaseObject.EndPosition, objectN.Position) < stack_distance))
{
stackBaseIndex = n;
// HitObjects after the specified update range haven't been reset yet
objectN.StackHeight = 0;
}
}
if (stackBaseIndex > extendedEndIndex)
{
extendedEndIndex = stackBaseIndex;
if (extendedEndIndex == hitObjects.Count - 1)
break;
}
}
}
// Reverse pass for stack calculation.
int extendedStartIndex = startIndex;
for (int i = extendedEndIndex; i > startIndex; i--)
{
int n = i;
/* We should check every note which has not yet got a stack.
* Consider the case we have two interwound stacks and this will make sense.
*
* o <-1 o <-2
* o <-3 o <-4
*
* We first process starting from 4 and handle 2,
* then we come backwards on the i loop iteration until we reach 3 and handle 1.
* 2 and 1 will be ignored in the i loop because they already have a stack value.
*/
OsuHitObject objectI = hitObjects[i];
if (objectI.StackHeight != 0 || objectI is Spinner) continue;
double stackThreshold = objectI.TimePreempt * beatmapInfo.StackLeniency;
/* If this object is a hitcircle, then we enter this "special" case.
* It either ends with a stack of hitcircles only, or a stack of hitcircles that are underneath a slider.
* Any other case is handled by the "is Slider" code below this.
*/
if (objectI is HitCircle)
{
while (--n >= 0)
{
OsuHitObject objectN = hitObjects[n];
if (objectN is Spinner) continue;
double endTime = objectN.GetEndTime();
if (objectI.StartTime - endTime > stackThreshold)
// We are no longer within stacking range of the previous object.
break;
// HitObjects before the specified update range haven't been reset yet
if (n < extendedStartIndex)
{
objectN.StackHeight = 0;
extendedStartIndex = n;
}
/* This is a special case where hticircles are moved DOWN and RIGHT (negative stacking) if they are under the *last* slider in a stacked pattern.
* o==o <- slider is at original location
* o <- hitCircle has stack of -1
* o <- hitCircle has stack of -2
*/
if (objectN is Slider && Vector2Extensions.Distance(objectN.EndPosition, objectI.Position) < stack_distance)
{
int offset = objectI.StackHeight - objectN.StackHeight + 1;
for (int j = n + 1; j <= i; j++)
{
// For each object which was declared under this slider, we will offset it to appear *below* the slider end (rather than above).
OsuHitObject objectJ = hitObjects[j];
if (Vector2Extensions.Distance(objectN.EndPosition, objectJ.Position) < stack_distance)
objectJ.StackHeight -= offset;
}
// We have hit a slider. We should restart calculation using this as the new base.
// Breaking here will mean that the slider still has StackCount of 0, so will be handled in the i-outer-loop.
break;
}
if (Vector2Extensions.Distance(objectN.Position, objectI.Position) < stack_distance)
{
// Keep processing as if there are no sliders. If we come across a slider, this gets cancelled out.
//NOTE: Sliders with start positions stacking are a special case that is also handled here.
objectN.StackHeight = objectI.StackHeight + 1;
objectI = objectN;
}
}
}
else if (objectI is Slider)
{
/* We have hit the first slider in a possible stack.
* From this point on, we ALWAYS stack positive regardless.
*/
while (--n >= startIndex)
{
OsuHitObject objectN = hitObjects[n];
if (objectN is Spinner) continue;
if (objectI.StartTime - objectN.StartTime > stackThreshold)
// We are no longer within stacking range of the previous object.
break;
if (Vector2Extensions.Distance(objectN.EndPosition, objectI.Position) < stack_distance)
{
objectN.StackHeight = objectI.StackHeight + 1;
objectI = objectN;
}
}
}
}
}
private static void applyStackingOld(BeatmapInfo beatmapInfo, List<OsuHitObject> hitObjects)
{
for (int i = 0; i < hitObjects.Count; i++)
{
OsuHitObject currHitObject = hitObjects[i];
if (currHitObject.StackHeight != 0 && !(currHitObject is Slider))
continue;
double startTime = currHitObject.GetEndTime();
int sliderStack = 0;
for (int j = i + 1; j < hitObjects.Count; j++)
{
double stackThreshold = hitObjects[i].TimePreempt * beatmapInfo.StackLeniency;
if (hitObjects[j].StartTime - stackThreshold > startTime)
break;
// The start position of the hitobject, or the position at the end of the path if the hitobject is a slider
Vector2 position2 = currHitObject is Slider currSlider
? currSlider.Position + currSlider.Path.PositionAt(1)
: currHitObject.Position;
// Note the use of `StartTime` in the code below doesn't match stable's use of `EndTime`.
// This is because in the stable implementation, `UpdateCalculations` is not called on the inner-loop hitobject (j)
// and therefore it does not have a correct `EndTime`, but instead the default of `EndTime = StartTime`.
//
// Effects of this can be seen on https://osu.ppy.sh/beatmapsets/243#osu/1146 at sliders around 86647 ms, where
// if we use `EndTime` here it would result in unexpected stacking.
if (Vector2Extensions.Distance(hitObjects[j].Position, currHitObject.Position) < stack_distance)
{
currHitObject.StackHeight++;
startTime = hitObjects[j].StartTime;
}
else if (Vector2Extensions.Distance(hitObjects[j].Position, position2) < stack_distance)
{
// Case for sliders - bump notes down and right, rather than up and left.
sliderStack++;
hitObjects[j].StackHeight -= sliderStack;
startTime = hitObjects[j].StartTime;
}
}
}
}
}
}