A quadtree has limit on number of item in each nodes. Suppose a node has already has same number of item as the limit. If I add another item on same node the node should split and new item should be added there. What I dont understand, Is previously existed node should be shifted to the new node? or they will remain where they were (parent of newly craeted node)?
It's a quad tree so when you split it into 4 parts any entities belonging to the parent get divided between the children based on position.