From ccbb30cdda8370ad626b30a56d1d9c7f169d03ec Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Tue, 18 Jul 2023 19:52:45 +0900
Subject: [PATCH] Fix `ParticleSpewer` not correctly accounting for lower frame
 rates (and spawning less particles)

---
 osu.Game/Graphics/ParticleSpewer.cs | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/osu.Game/Graphics/ParticleSpewer.cs b/osu.Game/Graphics/ParticleSpewer.cs
index 8519cf0c59..02053e1be7 100644
--- a/osu.Game/Graphics/ParticleSpewer.cs
+++ b/osu.Game/Graphics/ParticleSpewer.cs
@@ -20,9 +20,9 @@ namespace osu.Game.Graphics
     {
         private readonly FallingParticle[] particles;
         private int currentIndex;
-        private double lastParticleAdded;
+        private double? lastParticleAdded;
 
-        private readonly double cooldown;
+        private readonly double timeBetweenSpawns;
         private readonly double maxDuration;
 
         /// <summary>
@@ -44,7 +44,7 @@ namespace osu.Game.Graphics
 
             particles = new FallingParticle[perSecond * (int)Math.Ceiling(maxDuration / 1000)];
 
-            cooldown = 1000f / perSecond;
+            timeBetweenSpawns = 1000f / perSecond;
             this.maxDuration = maxDuration;
         }
 
@@ -52,18 +52,27 @@ namespace osu.Game.Graphics
         {
             base.Update();
 
-            if (Active.Value && CanSpawnParticles && Math.Abs(Time.Current - lastParticleAdded) > cooldown)
+            Invalidate(Invalidation.DrawNode);
+
+            if (!Active.Value || !CanSpawnParticles)
             {
+                lastParticleAdded = null;
+                return;
+            }
+
+            while (lastParticleAdded == null || Math.Abs(Time.Current - lastParticleAdded.Value) > timeBetweenSpawns)
+            {
+                lastParticleAdded ??= Time.Current;
+
                 var newParticle = CreateParticle();
-                newParticle.StartTime = (float)Time.Current;
+                newParticle.StartTime = (float)lastParticleAdded;
 
                 particles[currentIndex] = newParticle;
 
                 currentIndex = (currentIndex + 1) % particles.Length;
-                lastParticleAdded = Time.Current;
-            }
 
-            Invalidate(Invalidation.DrawNode);
+                lastParticleAdded += timeBetweenSpawns;
+            }
         }
 
         /// <summary>