From 8d4e4cd37d6d67b77ab1843657d52c4b349448be Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tur=C3=A1nszki=20J=C3=A1nos?=
 <turanszkij@users.noreply.github.com>
Date: Sun, 12 Feb 2023 11:44:09 +0100
Subject: [PATCH] improved framerate locking

---
 WickedEngine/wiApplication.cpp | 15 ++++++++++-----
 WickedEngine/wiHelper.cpp      | 24 +++++++++++++++++-------
 WickedEngine/wiHelper.h        |  5 +++++
 WickedEngine/wiVersion.cpp     |  2 +-
 4 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/WickedEngine/wiApplication.cpp b/WickedEngine/wiApplication.cpp
index 02cfdc598..dfc5156d8 100644
--- a/WickedEngine/wiApplication.cpp
+++ b/WickedEngine/wiApplication.cpp
@@ -140,14 +140,19 @@ namespace wi
 
 		deltaTime = float(std::max(0.0, timer.record_elapsed_seconds()));
 
+		const float target_deltaTime = 1.0f / targetFrameRate;
+		if (framerate_lock && deltaTime < target_deltaTime)
+		{
+			wi::helper::QuickSleep((target_deltaTime - deltaTime) * 1000);
+			deltaTime += float(std::max(0.0, timer.record_elapsed_seconds()));
+		}
+
 		wi::input::Update(window, canvas);
 
 		// Wake up the events that need to be executed on the main thread, in thread safe manner:
 		wi::eventhandler::FireEvent(wi::eventhandler::EVENT_THREAD_SAFE_POINT, 0);
 
-		const float dt = framerate_lock ? (1.0f / targetFrameRate) : deltaTime;
-
-		fadeManager.Update(dt);
+		fadeManager.Update(deltaTime);
 
 		if (GetActivePath() != nullptr)
 		{
@@ -161,7 +166,7 @@ namespace wi
 		{
 			if (frameskip)
 			{
-				deltaTimeAccumulator += dt;
+				deltaTimeAccumulator += deltaTime;
 				if (deltaTimeAccumulator > 10)
 				{
 					// application probably lost control, fixed update would take too long
@@ -183,7 +188,7 @@ namespace wi
 		wi::profiler::EndRange(range); // Fixed Update
 
 		// Variable-timed update:
-		Update(dt);
+		Update(deltaTime);
 
 		Render();
 
diff --git a/WickedEngine/wiHelper.cpp b/WickedEngine/wiHelper.cpp
index 816ffc530..3d9f7b8a9 100644
--- a/WickedEngine/wiHelper.cpp
+++ b/WickedEngine/wiHelper.cpp
@@ -1236,14 +1236,23 @@ namespace wi::helper
 
 	void Spin(float milliseconds)
 	{
-		milliseconds /= 1000.0f;
-		std::chrono::high_resolution_clock::time_point t1 = std::chrono::high_resolution_clock::now();
-		double ms = 0;
-		while (ms < milliseconds)
+		const std::chrono::high_resolution_clock::time_point t1 = std::chrono::high_resolution_clock::now();
+		const double seconds = double(milliseconds) / 1000.0;
+		while (std::chrono::duration_cast<std::chrono::duration<double>>(std::chrono::high_resolution_clock::now() - t1).count() < seconds);
+	}
+
+	void QuickSleep(float milliseconds)
+	{
+		const std::chrono::high_resolution_clock::time_point t1 = std::chrono::high_resolution_clock::now();
+		const double seconds = double(milliseconds) / 1000.0;
+		const int sleep_millisec_accuracy = 1;
+		const double sleep_sec_accuracy = double(sleep_millisec_accuracy) / 1000.0;
+		while (std::chrono::duration_cast<std::chrono::duration<double>>(std::chrono::high_resolution_clock::now() - t1).count() < seconds)
 		{
-			std::chrono::high_resolution_clock::time_point t2 = std::chrono::high_resolution_clock::now();
-			std::chrono::duration<double> time_span = std::chrono::duration_cast<std::chrono::duration<double>>(t2 - t1);
-			ms = time_span.count();
+			if (seconds - (std::chrono::high_resolution_clock::now() - t1).count() > sleep_sec_accuracy)
+			{
+				std::this_thread::sleep_for(std::chrono::milliseconds(sleep_millisec_accuracy));
+			}
 		}
 	}
 
@@ -1251,6 +1260,7 @@ namespace wi::helper
 	{
 #ifdef PLATFORM_UWP
 		winrt::Windows::System::Launcher::LaunchUriAsync(winrt::Windows::Foundation::Uri(winrt::to_hstring(url)));
+		return;
 #endif // PLATFORM_UWP
 
 #ifdef PLATFORM_WINDOWS_DESKTOP
diff --git a/WickedEngine/wiHelper.h b/WickedEngine/wiHelper.h
index 813502339..3b54938f8 100644
--- a/WickedEngine/wiHelper.h
+++ b/WickedEngine/wiHelper.h
@@ -132,6 +132,11 @@ namespace wi::helper
 	// Spins for the given time and does nothing (OS can not overtake)
 	void Spin(float milliseconds);
 
+	// Sleeps if duration is long enough to wake up in time, Spins otherwise
+	//	This lets OS overtake thread if duration is long enough to remain accurate
+	//	Also spins for more accuracy if needed
+	void QuickSleep(float milliseconds);
+
 	// Opens URL in the default browser
 	void OpenUrl(const std::string& url);
 };
diff --git a/WickedEngine/wiVersion.cpp b/WickedEngine/wiVersion.cpp
index f695fbd77..2c96cadb4 100644
--- a/WickedEngine/wiVersion.cpp
+++ b/WickedEngine/wiVersion.cpp
@@ -9,7 +9,7 @@ namespace wi::version
 	// minor features, major updates, breaking compatibility changes
 	const int minor = 71;
 	// minor bug fixes, alterations, refactors, updates
-	const int revision = 149;
+	const int revision = 150;
 
 	const std::string version_string = std::to_string(major) + "." + std::to_string(minor) + "." + std::to_string(revision);