Sdk/System: Fix time loss when using max update rate

SDK/include/NDK/BaseSystem.inl

@@ -164,8 +164,10 @@ namespace Ndk
 				}
 				else
 				{
-					OnUpdate(m_maxUpdateRate);
-					m_updateCounter -= m_maxUpdateRate;
+					float updateRate = std::max(elapsedTime, m_maxUpdateRate);
+
+					OnUpdate(updateRate);
+					m_updateCounter -= updateRate;
 				}
 			}
 		}

tests/SDK/NDK/System.cpp

@@ -1,30 +1,40 @@
 #include <NDK/System.hpp>
 #include <Catch/catch.hpp>
-/*
+
 namespace
 {
 	class TestSystem : public Ndk::System<TestSystem>
 	{
 		public:
-			TestSystem(int value) :
-			m_value(value)
+			TestSystem() :
+			m_updateCounter(0),
+			m_elapsedTime(0.f)
 			{
 			}
 
-			int GetValue() const
-			{
-				return m_value;
-			}
-
 			~TestSystem() = default;
 
+			float GetElapsedTime() const
+			{
+				return m_elapsedTime;
+			}
+
+			std::size_t GetLoopCount() const
+			{
+				return m_updateCounter;
+			}
+
 			static Ndk::SystemIndex systemIndex;
 
 		private:
-			int m_value;
+			std::size_t m_updateCounter;
+			float m_elapsedTime;
 
 			void OnUpdate(float elapsedTime) override
 			{
+				++m_updateCounter;
+
+				m_elapsedTime += elapsedTime;
 			}
 	};
 
@@ -35,16 +45,63 @@ SCENARIO("System", "[NDK][SYSTEM]")
 {
 	GIVEN("Our TestSystem")
 	{
-		TestSystem testSystem(666);
+		TestSystem testSystem;
+		testSystem.SetMaximumUpdateRate(30.f);
 
-		WHEN("We clone it")
+		float maxTimePerFrame = 1 / 30.f;
+
+		WHEN("We update it with a higher framerate")
 		{
-			std::unique_ptr<Ndk::BaseSystem> clone = testSystem.Clone();
+			float timePerFrame = maxTimePerFrame / 2.f;
+			float elapsedTime = 2.f;
 
-			THEN("We should get a copy")
+			std::size_t loopCount = static_cast<std::size_t>(std::round(elapsedTime / timePerFrame));
+
+			for (std::size_t i = 0; i < loopCount; ++i)
+				testSystem.Update(timePerFrame);
+
+			CHECK(testSystem.GetLoopCount() == loopCount / 2);
+			CHECK(testSystem.GetElapsedTime() == Approx(elapsedTime).epsilon(timePerFrame));
+		}
+
+		WHEN("We update it with a lower framerate")
+		{
+			float timePerFrame = maxTimePerFrame * 2.f;
+			float elapsedTime = 10.f;
+
+			std::size_t loopCount = static_cast<std::size_t>(std::round(elapsedTime / timePerFrame));
+
+			for (std::size_t i = 0; i < loopCount; ++i)
+				testSystem.Update(timePerFrame);
+
+			CHECK(testSystem.GetLoopCount() == loopCount);
+			CHECK(testSystem.GetElapsedTime() == Approx(elapsedTime).epsilon(timePerFrame));
+
+			AND_WHEN("We suddenly increase framerate")
 			{
-				REQUIRE(static_cast<TestSystem*>(clone.get())->GetValue() == 666);
+				float newTimePerFrame = 1 / 300.f;
+				float newElapsedTime = 100.f;
+
+				std::size_t newLoopCount = static_cast<std::size_t>(std::round(newElapsedTime / newTimePerFrame));
+
+				for (std::size_t i = 0; i < newLoopCount; ++i)
+					testSystem.Update(newTimePerFrame);
+
+				CHECK(testSystem.GetLoopCount() == loopCount + newLoopCount / 10);
+				CHECK(testSystem.GetElapsedTime() == Approx(elapsedTime + newElapsedTime).epsilon(newTimePerFrame));
 			}
 		}
+
+
+		WHEN("We update it with a very low framerate")
+		{
+			float timePerFrame = 0.5f;
+
+			for (std::size_t i = 0; i < 10; ++i)
+				testSystem.Update(timePerFrame);
+
+			CHECK(testSystem.GetLoopCount() == 10);
+			CHECK(testSystem.GetElapsedTime() == Approx(5.f));
+		}
 	}
-}*/
+}

tests/SDK/NDK/Systems/PhysicsSystem2D.cpp

@@ -19,7 +19,7 @@ SCENARIO("PhysicsSystem2D", "[NDK][PHYSICSSYSTEM2D]")
 		Ndk::NodeComponent& nodeComponent = movingEntity->GetComponent<Ndk::NodeComponent>();
 		Ndk::PhysicsComponent2D& physicsComponent2D = movingEntity->AddComponent<Ndk::PhysicsComponent2D>();
 
-		world.GetSystem<Ndk::PhysicsSystem2D>().SetFixedUpdateRate(30.f);
+		world.GetSystem<Ndk::PhysicsSystem2D>().SetMaximumUpdateRate(0.f);
 
 		WHEN("We update the world")
 		{
@@ -43,7 +43,7 @@ SCENARIO("PhysicsSystem2D", "[NDK][PHYSICSSYSTEM2D]")
 
 			world.Update(1.f);
 
-			THEN("It should moved freely")
+			THEN("It should move freely")
 			{
 				REQUIRE(nodeComponent.GetPosition() == position);
 				movingAABB.Translate(position);