From 8ec138399af7e5a703a1e9b8b946f26dcd0c8473 Mon Sep 17 00:00:00 2001
From: Wojtek Figat <wojtek@figat.pl>
Date: Wed, 11 Jun 2025 18:40:35 +0200
Subject: [PATCH] Add higher level streaming time budget in frame based on idle
 time

---
 Source/Engine/Engine/Engine.cpp | 5 +++++
 Source/Engine/Level/Level.cpp   | 8 ++++++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/Source/Engine/Engine/Engine.cpp b/Source/Engine/Engine/Engine.cpp
index 5607432c2..4ea18a85c 100644
--- a/Source/Engine/Engine/Engine.cpp
+++ b/Source/Engine/Engine/Engine.cpp
@@ -76,6 +76,7 @@ FatalErrorType Engine::FatalError = FatalErrorType::None;
 bool Engine::IsRequestingExit = false;
 int32 Engine::ExitCode = 0;
 Window* Engine::MainWindow = nullptr;
+double EngineIdleTime = 0;
 
 int32 Engine::Main(const Char* cmdLine)
 {
@@ -190,7 +191,10 @@ int32 Engine::Main(const Char* cmdLine)
             if (timeToTick > 0.002)
             {
                 PROFILE_CPU_NAMED("Idle");
+                auto sleepStart = Platform::GetTimeSeconds();
                 Platform::Sleep(1);
+                auto sleepEnd = Platform::GetTimeSeconds();
+                EngineIdleTime += sleepEnd - sleepStart;
             }
         }
 
@@ -227,6 +231,7 @@ int32 Engine::Main(const Char* cmdLine)
             OnUpdate();
             OnLateUpdate();
             Time::OnEndUpdate();
+            EngineIdleTime = 0;
         }
 
         // Start physics simulation
diff --git a/Source/Engine/Level/Level.cpp b/Source/Engine/Level/Level.cpp
index 678eada1f..5516e6d53 100644
--- a/Source/Engine/Level/Level.cpp
+++ b/Source/Engine/Level/Level.cpp
@@ -251,6 +251,7 @@ public:
 };
 
 LevelService LevelServiceInstanceService;
+extern double EngineIdleTime;
 
 CriticalSection Level::ScenesLock;
 Array<Scene*> Level::Scenes;
@@ -863,6 +864,8 @@ void LevelImpl::flushActions()
     else if (Engine::GetFramesPerSecond() > 0)
         targetFps = (float)Engine::GetFramesPerSecond();
     context.TimeBudget = Level::StreamingFrameBudget / targetFps;
+    if (EngineIdleTime > 0.001)
+        context.TimeBudget += (float)(EngineIdleTime * 0.5); // Increase time budget if engine has some idle time for spare
 #if USE_EDITOR
     // Throttle up in Editor
     context.TimeBudget *= Editor::IsPlayMode ? 1.2f : 2.0f;
@@ -871,8 +874,9 @@ void LevelImpl::flushActions()
     // Throttle up in Debug
     context.TimeBudget *= 1.2f;
 #endif
-    if (context.TimeBudget <= ZeroTolerance)
-        context.TimeBudget = MAX_float;
+    if (context.TimeBudget <= 0.0f)
+        context.TimeBudget = MAX_float; // Unlimited if 0
+    context.TimeBudget = Math::Max(context.TimeBudget, 0.001f); // Minimum 1ms
 
     // Runs actions in order
     ScopeLock lock(_sceneActionsLocker);