Physics2D/PhysWorld2D: Add invStepCount argument to pre/post steps callbacks

ChangeLog.md

@@ -94,6 +94,7 @@ Nazara Engine:
 - ⚠️ Stream::ReadLine will now returns empty lines if present in the file
 - Fixed cubemaps seams with OpenGL
 - HandledObject movement constructor/assignement operator are now marked noexcept
+- ⚠️ PhysWorld2D callbacks OnPhysWorld2DPreStep and OnPhysWorld2DPostStep now takes a invStepCount depending on the number of step taken this update, fixing force application and other
 
 Nazara Development Kit:
 - Added ImageWidget (#139)

include/Nazara/Physics2D/PhysWorld2D.hpp

@@ -123,8 +123,8 @@ namespace Nz
 				float fraction;
 			};
 
-			NazaraSignal(OnPhysWorld2DPreStep, const PhysWorld2D* /*physWorld*/);
+			NazaraSignal(OnPhysWorld2DPreStep, const PhysWorld2D* /*physWorld*/, float /*invStepCount*/);
-			NazaraSignal(OnPhysWorld2DPostStep, const PhysWorld2D* /*physWorld*/);
+			NazaraSignal(OnPhysWorld2DPostStep, const PhysWorld2D* /*physWorld*/, float /*invStepCount*/);
 
 		private:
 			void InitCallbacks(cpCollisionHandler* handler, const Callback& callbacks);

src/Nazara/Physics2D/PhysWorld2D.cpp

@@ -311,14 +311,15 @@ namespace Nz
 	{
 		m_timestepAccumulator += timestep;
 
-		std::size_t stepCount = 0;
+		std::size_t stepCount = std::min(static_cast<std::size_t>(m_timestepAccumulator / m_stepSize), m_maxStepCount);
-		while (m_timestepAccumulator >= m_stepSize && stepCount < m_maxStepCount)
+		float invStepCount = 1.f / stepCount;
+		for (std::size_t i = 0; i < stepCount; ++i)
 		{
-			OnPhysWorld2DPreStep(this);
+			OnPhysWorld2DPreStep(this, invStepCount);
 
 			cpSpaceStep(m_handle, m_stepSize);
 
-			OnPhysWorld2DPostStep(this);
+			OnPhysWorld2DPostStep(this, invStepCount);
 			if (!m_rigidPostSteps.empty())
 			{
 				for (const auto& pair : m_rigidPostSteps)
@@ -331,7 +332,6 @@ namespace Nz
 			}
 
 			m_timestepAccumulator -= m_stepSize;
-			stepCount++;
 		}
 	}