BGE: [#19836] Recursive Parenting in game crashes Blender. Added parenting loop detection.

source/gameengine/Ketsji/KX_GameObject.cpp

@@ -234,7 +234,11 @@ KX_GameObject* KX_GameObject::GetParent()
 void KX_GameObject::SetParent(KX_Scene *scene, KX_GameObject* obj, bool addToCompound, bool ghost)
 {
 	// check on valid node in case a python controller holds a reference to a deleted object
-	if (obj && GetSGNode() && obj->GetSGNode() && GetSGNode()->GetSGParent() != obj->GetSGNode())
+	if (obj && 
+		GetSGNode() &&			// object is not zombi
+		obj->GetSGNode() &&		// object is not zombi
+		GetSGNode()->GetSGParent() != obj->GetSGNode() &&	// not already parented to same object
+		!GetSGNode()->IsAncessor(obj->GetSGNode()))			// no parenting loop
 	{
 		// Make sure the objects have some scale
 		MT_Vector3 scale1 = NodeGetWorldScaling();

source/gameengine/SceneGraph/SG_Node.cpp

@@ -150,6 +150,12 @@ GetRootSGParent(
 	return (m_SGparent ? (const SG_Node*) m_SGparent->GetRootSGParent() : (const SG_Node*) this);
 }
 
+bool SG_Node::IsAncessor(const SG_Node* child) const
+{
+	return (!child->m_SGparent) ? false : 
+		(child->m_SGparent == this) ? true : IsAncessor(child->m_SGparent);
+}
+
 	void 
 SG_Node::
 DisconnectFromParent(

source/gameengine/SceneGraph/SG_Node.h

@@ -77,6 +77,13 @@ public:
 		SG_Node* child
 	);
 
+	/**
+	 * Return true if the node is the ancessor of child
+	 */
+		bool
+	IsAncessor(
+		const SG_Node* child
+	) const;
 	/** 
 	 * Get the current list of children. Do not use this interface for
 	 * adding or removing children please use the methods of this class for