Physics2D: Handle kinematic objects properly

include/Nazara/Physics2D/RigidBody2D.hpp

@@ -44,13 +44,14 @@ namespace Nz
 			const Collider2DRef& GetGeom() const;
 			cpBody* GetHandle() const;
 			float GetMass() const;
+			float GetMomentOfInertia() const;
 			Vector2f GetPosition() const;
 			float GetRotation() const;
 			void* GetUserdata() const;
 			Vector2f GetVelocity() const;
 			PhysWorld2D* GetWorld() const;
 
-			bool IsMoveable() const;
+			bool IsKinematic() const;
 			bool IsSleeping() const;
 
 			void SetAngularVelocity(float angularVelocity);
@@ -70,7 +71,8 @@ namespace Nz
 			NazaraSignal(OnRigidBody2DRelease, RigidBody2D* /*rigidBody*/);
 
 		private:
-			void Create(float mass = 1.f, float moment = 1.f);
+			void CopyBodyData(cpBody* body);
+			cpBody* Create(float mass = 1.f, float moment = 1.f);
 			void Destroy();
 
 			std::vector<cpShape*> m_shapes;

src/Nazara/Physics2D/Collider2D.cpp

@@ -143,9 +143,9 @@ namespace Nz
 		return ColliderType2D_Null;
 	}
 
-	float NullCollider2D::ComputeMomentOfInertia(float /*mass*/) const
+	float NullCollider2D::ComputeMomentOfInertia(float mass) const
 	{
-		return 0.f;
+		return (mass > 0.f) ? 1.f : 0.f; //< Null inertia is only possible for static/kinematic objects
 	}
 
 	void NullCollider2D::CreateShapes(RigidBody2D* /*body*/, std::vector<cpShape*>& /*shapes*/) const

src/Nazara/Physics2D/RigidBody2D.cpp

@@ -27,10 +27,8 @@ namespace Nz
 	{
 		NazaraAssert(m_world, "Invalid world");
 
-		Create();
+		m_handle = Create(mass);
-
 		SetGeom(geom);
-		SetMass(mass);
 	}
 
 	RigidBody2D::RigidBody2D(const RigidBody2D& object) :
@@ -43,30 +41,13 @@ namespace Nz
 		NazaraAssert(m_world, "Invalid world");
 		NazaraAssert(m_geom, "Invalid geometry");
 
-		Create();
+		m_handle = Create(object.GetMass(), object.GetMomentOfInertia());
+		SetGeom(object.GetGeom(), false);
 
-		cpBodySetMass(m_handle, cpBodyGetMass(object.GetHandle()));
+		CopyBodyData(object.GetHandle());
-		cpBodySetMoment(m_handle, cpBodyGetMoment(object.GetHandle()));
 
-		SetGeom(object.GetGeom());
+		for (int i = 0; i < m_shapes.size(); ++i)
-		SetMass(object.GetMass());
-
-		cpBodySetForce(m_handle, cpBodyGetForce(object.GetHandle()));
-		cpBodySetTorque(m_handle, cpBodyGetTorque(object.GetHandle()));
-
-		cpBodySetAngle(m_handle, cpBodyGetAngle(object.GetHandle()));
-		cpBodySetAngularVelocity(m_handle, cpBodyGetAngularVelocity(object.GetHandle()));
-		cpBodySetCenterOfGravity(m_handle, cpBodyGetCenterOfGravity(object.GetHandle()));
-		cpBodySetPosition(m_handle, cpBodyGetPosition(object.GetHandle()));
-		cpBodySetVelocity(m_handle, cpBodyGetVelocity(object.GetHandle()));
-
-		for (int i = 0; i != m_shapes.size(); ++i)
 			m_shapes[i]->bb = cpShapeCacheBB(object.m_shapes[i]);
-
-		cpBodySetMass(m_handle, cpBodyGetMass(object.GetHandle()));
-		cpBodySetMoment(m_handle, cpBodyGetMoment(object.GetHandle()));
-
-		m_handle->m = object.GetHandle()->m;
 	}
 
 	RigidBody2D::RigidBody2D(RigidBody2D&& object) :
@@ -172,6 +153,11 @@ namespace Nz
 		return m_mass;
 	}
 
+	float RigidBody2D::GetMomentOfInertia() const
+	{
+		return float(cpBodyGetMoment(m_handle));
+	}
+
 	Vector2f RigidBody2D::GetCenterOfGravity(CoordSys coordSys) const
 	{
 		cpVect cog = cpBodyGetCenterOfGravity(m_handle);
@@ -216,9 +202,9 @@ namespace Nz
 		return m_world;
 	}
 
-	bool RigidBody2D::IsMoveable() const
+	bool RigidBody2D::IsKinematic() const
 	{
-		return m_mass > 0.f;
+		return m_mass <= 0.f;
 	}
 
 	bool RigidBody2D::IsSleeping() const
@@ -240,8 +226,12 @@ namespace Nz
 			cpFloat mass = cpBodyGetMass(m_handle);
 			cpFloat moment = cpBodyGetMoment(m_handle);
 
+			cpBody* newHandle = Create(static_cast<float>(mass), static_cast<float>(moment));
+
+			CopyBodyData(m_handle);
 			Destroy();
-			Create(static_cast<float>(mass), static_cast<float>(moment));
+
+			m_handle = newHandle;
 		}
 
 		if (geom)
@@ -299,8 +289,7 @@ namespace Nz
 
 	void RigidBody2D::SetMassCenter(const Vector2f& center)
 	{
-		if (m_mass > 0.f)
+		cpBodySetCenterOfGravity(m_handle, cpv(center.x, center.y));
-			cpBodySetCenterOfGravity(m_handle, cpv(center.x, center.y));
 	}
 
 	void RigidBody2D::SetMomentOfInertia(float moment)
@@ -364,12 +353,28 @@ namespace Nz
 		return *this;
 	}
 
-	void RigidBody2D::Create(float mass, float moment)
+	void RigidBody2D::CopyBodyData(cpBody* body)
 	{
-		m_handle = cpBodyNew(mass, moment);
+		cpBodySetAngle(m_handle, cpBodyGetAngle(body));
-		cpBodySetUserData(m_handle, this);
+		cpBodySetAngularVelocity(m_handle, cpBodyGetAngularVelocity(body));
+		cpBodySetCenterOfGravity(m_handle, cpBodyGetCenterOfGravity(body));
+		cpBodySetForce(m_handle, cpBodyGetForce(body));
+		cpBodySetPosition(m_handle, cpBodyGetPosition(body));
+		cpBodySetTorque(m_handle, cpBodyGetTorque(body));
+		cpBodySetVelocity(m_handle, cpBodyGetVelocity(body));
+	}
 
-		cpSpaceAddBody(m_world->GetHandle(), m_handle);
+	cpBody* RigidBody2D::Create(float mass, float moment)
+	{
+		cpBody* handle = cpBodyNew(mass, moment);
+		cpBodySetUserData(handle, this);
+
+		if (mass <= 0.f)
+			cpBodySetType(handle, CP_BODY_TYPE_KINEMATIC);
+
+		cpSpaceAddBody(m_world->GetHandle(), handle);
+
+		return handle;
 	}
 
 	void RigidBody2D::Destroy()

tests/Engine/Physics2D/RigidBody2D.cpp

@@ -128,7 +128,7 @@ SCENARIO("RigidBody2D", "[PHYSICS2D][RIGIDBODY2D]")
 				CHECK(body.GetUserdata() == &userData);
 				CHECK(body.GetVelocity() == Nz::Vector2f::Zero());
 
-				CHECK(body.IsMoveable() == true);
+				CHECK(body.IsKinematic() == false);
 				CHECK(body.IsSleeping() == false);
 			}
 		}
@@ -315,4 +315,4 @@ void EQUALITY(const Nz::RigidBody2D& left, const Nz::RigidBody2D& right)
 	CHECK(left.GetRotation() == right.GetRotation());
 	CHECK(left.GetUserdata() == right.GetUserdata());
 	CHECK(left.GetVelocity() == right.GetVelocity());
-}
+}