UPBGE: Fix removed constraints when suspending physics.

Previously when we was suspending physics of an object using constraints,
they were removed. This behaviour could be needed in some rare case but
for the most case where the user just want to optimize physics computation
the engine should keep the constraints.

To do so the constraints have to be removed from the dynamic world but not
removed from the controller or deleted in RemoveCcdPhysicsController. In
the same time AddCcdPhysicsController iterate over all the constraint in
the activated controller and add they in the dynamic world.

Unfortunately there's some limitation, first we could not do redundant
operation in removing and adding of the constraint in the world, second
we have to keep the disable collision between bodies flag used when adding
a constraint into world. To solve both of these issues the user pointer
of the constraint are used to store a new type: CcdConstraint (in
CcdPhysicsController). This new type only store the disable collision
flag and a boolean named m_active set to true when the constraint is added
in world else to false when removed.
Two functions are added to clean the code: RemoveConstraint and RestoreConstraint.

On python API side the user could specify to remove or not the constraints
when calling KX_GameObject.suspendPhysics(freeConstraints=False).

doc/python_api/rst/bge_types/bge.types.KX_GameObject.rst

@@ -741,10 +741,14 @@ base class --- :class:`SCA_IObject`
       :arg angular_damping: Angular ("rotational") damping factor.
       :type angular_damping: float ∈ [0, 1]
 
-   .. method:: suspendPhysics()
+   .. method:: suspendPhysics([freeConstraints])
 
       Suspends physics for this object.
 
+      :arg freeConstraints: When set to `True` physics constraints used by the object are deleted.
+          Else when `False` (the default) constraints are restored when restoring physics.
+      :type freeConstraints: bool
+
    .. method:: restorePhysics()
 
       Resumes physics for this object. Also reinstates collisions.

source/gameengine/Ketsji/KX_GameObject.cpp

@@ -1911,7 +1911,7 @@ PyMethodDef KX_GameObject::Methods[] = {
 	{"getReactionForce", (PyCFunction) KX_GameObject::sPyGetReactionForce, METH_NOARGS},
 	{"alignAxisToVect",(PyCFunction) KX_GameObject::sPyAlignAxisToVect, METH_VARARGS},
 	{"getAxisVect",(PyCFunction) KX_GameObject::sPyGetAxisVect, METH_O},
-	{"suspendPhysics", (PyCFunction)KX_GameObject::sPySuspendPhysics, METH_NOARGS},
+	{"suspendPhysics", (PyCFunction)KX_GameObject::sPySuspendPhysics, METH_VARARGS},
 	{"restorePhysics", (PyCFunction)KX_GameObject::sPyRestorePhysics,METH_NOARGS},
 	{"suspendDynamics", (PyCFunction)KX_GameObject::sPySuspendDynamics, METH_VARARGS},
 	{"restoreDynamics", (PyCFunction)KX_GameObject::sPyRestoreDynamics,METH_NOARGS},
@@ -3561,10 +3561,16 @@ PyObject *KX_GameObject::PyApplyImpulse(PyObject *args)
 	return nullptr;
 }
 
-PyObject *KX_GameObject::PySuspendPhysics()
+PyObject *KX_GameObject::PySuspendPhysics(PyObject *args)
 {
+	int freeConstraints = false;
+
+	if (!PyArg_ParseTuple(args, "|i:suspendPhysics", &freeConstraints)) {
+		return nullptr;
+	}
+
 	if (GetPhysicsController()) {
-		GetPhysicsController()->SuspendPhysics();
+		GetPhysicsController()->SuspendPhysics((bool)freeConstraints);
 	}
 	Py_RETURN_NONE;
 }

source/gameengine/Ketsji/KX_GameObject.h

@@ -952,7 +952,7 @@ class KX_GameObject : public SCA_IObject
 	KX_PYMETHOD_O(KX_GameObject,SetState);
 	KX_PYMETHOD_VARARGS(KX_GameObject,AlignAxisToVect);
 	KX_PYMETHOD_O(KX_GameObject,GetAxisVect);
-	KX_PYMETHOD_NOARGS(KX_GameObject,SuspendPhysics);
+	KX_PYMETHOD_VARARGS(KX_GameObject,SuspendPhysics);
 	KX_PYMETHOD_NOARGS(KX_GameObject,RestorePhysics);
 	KX_PYMETHOD_VARARGS(KX_GameObject,SuspendDynamics);
 	KX_PYMETHOD_NOARGS(KX_GameObject,RestoreDynamics);

source/gameengine/Ketsji/KX_PyConstraintBinding.cpp

@@ -584,7 +584,7 @@ static PyObject *gPyRemoveConstraint(PyObject *self,
 	{
 		if (PHY_GetActiveEnvironment())
 		{
-			PHY_GetActiveEnvironment()->RemoveConstraintById(constraintid);
+			PHY_GetActiveEnvironment()->RemoveConstraintById(constraintid, true);
 		}
 	}
 	else {

source/gameengine/Ketsji/KX_SCA_DynamicActuator.cpp

@@ -144,7 +144,7 @@ bool KX_SCA_DynamicActuator::Update()
 		}
 		case KX_DYN_DISABLE_PHYSICS:
 		{
-			controller->SuspendPhysics();
+			controller->SuspendPhysics(false);
 			break;
 		}
 	}

source/gameengine/Physics/Bullet/CcdPhysicsController.cpp

@@ -231,6 +231,13 @@ class BlenderBulletMotionState : public btMotionState
 	}
 };
 
+CcdPhysicsController::CcdConstraint::CcdConstraint(bool disableCollision)
+	:m_disableCollision(disableCollision),
+	m_active(false)
+{
+}
+
+
 btRigidBody *CcdPhysicsController::GetRigidBody()
 {
 	return btRigidBody::upcast(m_object);
@@ -650,7 +657,7 @@ CcdPhysicsController::~CcdPhysicsController()
 {
 	//will be reference counted, due to sharing
 	if (m_cci.m_physicsEnv)
-		m_cci.m_physicsEnv->RemoveCcdPhysicsController(this);
+		m_cci.m_physicsEnv->RemoveCcdPhysicsController(this, true);
 
 	if (m_MotionState)
 		delete m_MotionState;
@@ -833,7 +840,7 @@ void CcdPhysicsController::SetPhysicsEnvironment(class PHY_IPhysicsEnvironment *
 		// since the environment is changing, we must also move the controler to the
 		// new environment. Note that we don't handle sensor explicitly: this
 		// function can be called on sensor but only when they are not registered
-		if (m_cci.m_physicsEnv->RemoveCcdPhysicsController(this))
+		if (m_cci.m_physicsEnv->RemoveCcdPhysicsController(this, true))
 		{
 			physicsEnv->AddCcdPhysicsController(this);
 
@@ -1015,9 +1022,9 @@ void CcdPhysicsController::RefreshCollisions()
 	GetPhysicsEnvironment()->UpdateCcdPhysicsController(this, GetMass(), m_object->getCollisionFlags(), handle->m_collisionFilterGroup, handle->m_collisionFilterMask);
 }
 
-void CcdPhysicsController::SuspendPhysics()
+void CcdPhysicsController::SuspendPhysics(bool freeConstraints)
 {
-	GetPhysicsEnvironment()->RemoveCcdPhysicsController(this);
+	GetPhysicsEnvironment()->RemoveCcdPhysicsController(this, freeConstraints);
 }
 
 void CcdPhysicsController::RestorePhysics()
@@ -1508,7 +1515,7 @@ void CcdPhysicsController::AddCompoundChild(PHY_IPhysicsController *child)
 	// must update the broadphase cache,
 	GetPhysicsEnvironment()->RefreshCcdPhysicsController(this);
 	// remove the children
-	GetPhysicsEnvironment()->RemoveCcdPhysicsController(childCtrl);
+	GetPhysicsEnvironment()->RemoveCcdPhysicsController(childCtrl, true);
 }
 
 /* Reverse function of the above, it will remove a shape from a compound shape

source/gameengine/Physics/Bullet/CcdPhysicsController.h

@@ -515,6 +515,17 @@ class CleanPairCallback : public btOverlapCallback
 /// CcdPhysicsController is a physics object that supports continuous collision detection and time of impact based physics resolution.
 class CcdPhysicsController : public PHY_IPhysicsController
 {
+public:
+	/// Constraint user data.
+	struct CcdConstraint
+	{
+		CcdConstraint(bool m_disableCollision);
+		/// Disable collision between constrained objects?
+		bool m_disableCollision;
+		/// The constraint is added in dynamic world?
+		bool m_active;
+	};
+
 protected:
 	btCollisionObject *m_object;
 	BlenderBulletCharacterController *m_characterController;
@@ -683,7 +694,7 @@ class CcdPhysicsController : public PHY_IPhysicsController
 
 	virtual void ResolveCombinedVelocities(float linvelX, float linvelY, float linvelZ, float angVelX, float angVelY, float angVelZ);
 	virtual void RefreshCollisions();
-	virtual void SuspendPhysics();
+	virtual void SuspendPhysics(bool freeConstraints);
 	virtual void RestorePhysics();
 	virtual void SuspendDynamics(bool ghost);
 	virtual void RestoreDynamics();