From f2201404f3d383e375324ed30ef4083de18aa2c4 Mon Sep 17 00:00:00 2001
From: SirLynix <lynix680@gmail.com>
Date: Mon, 18 Dec 2023 12:15:08 +0100
Subject: [PATCH] Core/Clock: Add Tick method

---
 include/Nazara/Core/Clock.hpp             |  2 ++
 include/Nazara/Core/Clock.inl             | 31 ++++++++++++++++++++++-
 tests/UnitTests/Engine/Core/ClockTest.cpp | 15 +++++++++++
 3 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/include/Nazara/Core/Clock.hpp b/include/Nazara/Core/Clock.hpp
index f771ca8ba..1a9b6851e 100644
--- a/include/Nazara/Core/Clock.hpp
+++ b/include/Nazara/Core/Clock.hpp
@@ -32,6 +32,8 @@ namespace Nz
 			Time Restart(Time startingPoint = Time::Zero(), bool paused = false);
 			std::optional<Time> RestartIfOver(Time time);
 
+			bool Tick(Time time);
+
 			void Unpause();
 
 			Clock& operator=(const Clock& clock) = default;
diff --git a/include/Nazara/Core/Clock.inl b/include/Nazara/Core/Clock.inl
index a1c27c724..c32c03fd7 100644
--- a/include/Nazara/Core/Clock.inl
+++ b/include/Nazara/Core/Clock.inl
@@ -97,8 +97,10 @@ namespace Nz
 	* \brief Restart the clock if more than time elapsed
 	* \return If more than time elapsed since creation or last restart call
 	*
-	* Restarts the clock, putting its time counter back to zero
+	* Restarts the clock if over a specified duration, putting its time counter back to zero
 	* This function allows to check the elapsed time of a clock and restart it if over some value in a single call, preventing some loss between GetElapsedTime and Restart
+	*
+	* \seealso Tick
 	*/
 	template<bool HighPrecision>
 	std::optional<Time> Clock<HighPrecision>::RestartIfOver(Time time)
@@ -118,6 +120,33 @@ namespace Nz
 		return elapsedTime;
 	}
 
+	/*!
+	* \brief Restart the clock if more than time elapsed, but keeps the overflow
+	* \return True if more time has passed than time, false otherwise
+	*
+	* Restarts the clock if over a specified duration, but keeps the extra time (for example if elapsed time is 1.05s and this function is called with 1s, the clock will restart at 0.05s)
+	* This function allows to execute a code at periodic interval (tick) without losing time
+	*
+	* \seealso RestartIfOver
+	*/
+	template<bool HighPrecision>
+	bool Clock<HighPrecision>::Tick(Time time)
+	{
+		Time now = Now();
+
+		Time elapsedTime = m_elapsedTime;
+		if (!m_paused)
+			elapsedTime += now - m_refTime;
+
+		if (elapsedTime < time)
+			return false;
+
+		m_elapsedTime = elapsedTime - time;
+		m_refTime = now;
+
+		return true;
+	}
+
 
 	/*!
 	* \brief Unpause the clock
diff --git a/tests/UnitTests/Engine/Core/ClockTest.cpp b/tests/UnitTests/Engine/Core/ClockTest.cpp
index a2ae4cf7f..7fba8cb04 100644
--- a/tests/UnitTests/Engine/Core/ClockTest.cpp
+++ b/tests/UnitTests/Engine/Core/ClockTest.cpp
@@ -48,5 +48,20 @@ SCENARIO("Clock", "[CORE][CLOCK]")
 				CHECK(clock.GetElapsedTime() != initialTime);
 			}
 		}
+
+		WHEN("We restart if over")
+		{
+			clock.Restart(Nz::Time::Milliseconds(1'500), true);
+			CHECK(clock.RestartIfOver(Nz::Time::Microseconds(1'000)) == Nz::Time::Milliseconds(1'500));
+			CHECK(clock.GetElapsedTime() == Nz::Time::Zero());
+		}
+
+		WHEN("We tick it")
+		{
+			clock.Restart(Nz::Time::Milliseconds(1'500), true);
+			CHECK(clock.Tick(Nz::Time::Milliseconds(1'000)));
+			CHECK(clock.GetElapsedTime() == Nz::Time::Milliseconds(500));
+			CHECK_FALSE(clock.Tick(Nz::Time::Milliseconds(1'000)));
+		}
 	}
 }