From 7a04c6f83b0e5b1fc140c22e176f06ccd803f29d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=B4me=20Leclercq?=
 <jerome.leclercq@fullcycle.games>
Date: Wed, 17 Jan 2018 17:13:50 +0100
Subject: [PATCH] Physics2D/RigidBody2D: Add
 EnableSimulation/IsSimulationEnabled

---
 ChangeLog.md                             |  1 +
 include/Nazara/Physics2D/RigidBody2D.hpp |  7 +++
 src/Nazara/Physics2D/RigidBody2D.cpp     | 70 ++++++++++++++++++++----
 3 files changed, 68 insertions(+), 10 deletions(-)

diff --git a/ChangeLog.md b/ChangeLog.md
index 27ff205ed..18a8b61c2 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -57,6 +57,7 @@ Nazara Engine:
 - Add JPEG image saver
 - Update Constraint2Ds classes (Add : Ref, Library, ConstRef, New function and Update : ctors)
 - Fix LuaClass not working correctly when Lua stack wasn't empty
+- Add RigidBody2D simulation control (via EnableSimulation and IsSimulationEnabled), which allows to disable physics and collisions at will.
 
 Nazara Development Kit:
 - Added ImageWidget (#139)
diff --git a/include/Nazara/Physics2D/RigidBody2D.hpp b/include/Nazara/Physics2D/RigidBody2D.hpp
index 49517aac3..4ca95717f 100644
--- a/include/Nazara/Physics2D/RigidBody2D.hpp
+++ b/include/Nazara/Physics2D/RigidBody2D.hpp
@@ -36,6 +36,8 @@ namespace Nz
 			void AddImpulse(const Vector2f& impulse, const Vector2f& point, CoordSys coordSys = CoordSys_Global);
 			void AddTorque(float torque);
 
+			void EnableSimulation(bool simulation);
+
 			Rectf GetAABB() const;
 			float GetAngularVelocity() const;
 			Vector2f GetCenterOfGravity(CoordSys coordSys = CoordSys_Local) const;
@@ -51,6 +53,7 @@ namespace Nz
 			PhysWorld2D* GetWorld() const;
 
 			bool IsKinematic() const;
+			bool IsSimulationEnabled() const;
 			bool IsSleeping() const;
 			bool IsStatic() const;
 
@@ -76,6 +79,8 @@ namespace Nz
 		private:
 			cpBody* Create(float mass = 1.f, float moment = 1.f);
 			void Destroy();
+			void RegisterToSpace();
+			void UnregisterFromSpace();
 
 			static void CopyBodyData(cpBody* from, cpBody* to);
 
@@ -84,6 +89,8 @@ namespace Nz
 			cpBody* m_handle;
 			void* m_userData;
 			PhysWorld2D* m_world;
+			bool m_isRegistered;
+			bool m_isSimulationEnabled;
 			bool m_isStatic;
 			float m_gravityFactor;
 			float m_mass;
diff --git a/src/Nazara/Physics2D/RigidBody2D.cpp b/src/Nazara/Physics2D/RigidBody2D.cpp
index fd54909b4..1bb39fbc1 100644
--- a/src/Nazara/Physics2D/RigidBody2D.cpp
+++ b/src/Nazara/Physics2D/RigidBody2D.cpp
@@ -20,6 +20,8 @@ namespace Nz
 	m_geom(),
 	m_userData(nullptr),
 	m_world(world),
+	m_isRegistered(false),
+	m_isSimulationEnabled(true),
 	m_isStatic(false),
 	m_gravityFactor(1.f),
 	m_mass(mass)
@@ -34,6 +36,8 @@ namespace Nz
 	m_geom(object.m_geom),
 	m_userData(object.m_userData),
 	m_world(object.m_world),
+	m_isRegistered(false),
+	m_isSimulationEnabled(true),
 	m_isStatic(object.m_isStatic),
 	m_gravityFactor(object.m_gravityFactor),
 	m_mass(object.GetMass())
@@ -121,6 +125,19 @@ namespace Nz
 		cpBodySetTorque(m_handle, cpBodyGetTorque(m_handle) + ToRadians(torque));
 	}
 
+	void RigidBody2D::EnableSimulation(bool simulation)
+	{
+		if (m_isRegistered != simulation)
+		{
+			m_isRegistered = simulation;
+
+			if (simulation)
+				RegisterToSpace();
+			else
+				UnregisterFromSpace();
+		}
+	}
+
 	Rectf RigidBody2D::GetAABB() const
 	{
 		if (m_shapes.empty())
@@ -217,6 +234,11 @@ namespace Nz
 		return m_mass <= 0.f;
 	}
 
+	bool RigidBody2D::IsSimulationEnabled() const
+	{
+		return m_isRegistered;
+	}
+
 	bool RigidBody2D::IsSleeping() const
 	{
 		return cpBodyIsSleeping(m_handle) != 0;
@@ -244,6 +266,7 @@ namespace Nz
 			cpBody* newHandle = Create(static_cast<float>(mass), static_cast<float>(moment));
 
 			CopyBodyData(m_handle, newHandle);
+
 			Destroy();
 
 			m_handle = newHandle;
@@ -258,10 +281,10 @@ namespace Nz
 
 		cpSpace* space = m_world->GetHandle();
 		for (cpShape* shape : m_shapes)
-		{
 			cpShapeSetUserData(shape, this);
-			cpSpaceAddShape(space, shape);
-		}
+
+		if (m_isSimulationEnabled)
+			RegisterToSpace();
 
 		if (recomputeMoment)
 		{
@@ -384,6 +407,7 @@ namespace Nz
 		OnRigidBody2DRelease = std::move(object.OnRigidBody2DRelease);
 
 		m_handle             = object.m_handle;
+		m_isRegistered          = object.m_isRegistered;
 		m_isStatic           = object.m_isStatic;
 		m_geom               = std::move(object.m_geom);
 		m_gravityFactor      = object.m_gravityFactor;
@@ -417,28 +441,54 @@ namespace Nz
 			handle = cpBodyNew(mass, moment);
 
 		cpBodySetUserData(handle, this);
-		cpSpaceAddBody(m_world->GetHandle(), handle);
 
 		return handle;
 	}
 
 	void RigidBody2D::Destroy()
 	{
+		UnregisterFromSpace();
+
 		cpSpace* space = m_world->GetHandle();
 		for (cpShape* shape : m_shapes)
-		{
-			cpSpaceRemoveShape(space, shape);
 			cpShapeFree(shape);
-		}
 
 		if (m_handle)
-		{
-			cpSpaceRemoveBody(space, m_handle);
 			cpBodyFree(m_handle);
-		}
+
 		m_shapes.clear();
 	}
 
+	void RigidBody2D::RegisterToSpace()
+	{
+		if (!m_isRegistered)
+		{
+			cpSpace* space = m_world->GetHandle();
+			for (cpShape* shape : m_shapes)
+				cpSpaceAddShape(space, shape);
+
+			if (m_handle)
+				cpSpaceAddBody(space, m_handle);
+
+			m_isRegistered = true;
+		}
+	}
+
+	void RigidBody2D::UnregisterFromSpace()
+	{
+		if (m_isRegistered)
+		{
+			cpSpace* space = m_world->GetHandle();
+			for (cpShape* shape : m_shapes)
+				cpSpaceRemoveShape(space, shape);
+
+			if (m_handle)
+				cpSpaceRemoveBody(space, m_handle);
+
+			m_isRegistered = false;
+		}
+	}
+
 	void RigidBody2D::CopyBodyData(cpBody* from, cpBody* to)
 	{
 		cpBodySetAngle(to, cpBodyGetAngle(from));