List<> Saving / Serializing

Unity Engine
1

I’ve setup a Quadtree data structure that I’m using for some terrain data. I am running into a problem regarding the serialising of List<> objects. My structure is something like the following:

[Serializable]
public class TerrainScript : MonoBehaviour 
{
    public QuadTree m_QuadTree;
}

[Serializable]
public class QuadTree
{
    public QuadTreeNode m_root;
}

[Serializable]
public class QuadTreeNode
{
    public List<QuadTreeNode> m_nodes = new List<QuadTreeNode>(); (Getting NullReferenceException when accessing these contents)
}

It works fine, up until I close Unity or run the game and try to continue editing the terrain. It is like it has tried to reconstruct my objects but hasn’t been able to. I get a NullReferenceException whenever anything tries to access the list in QuadTreeNode. Am I missing something when it comes to serialization? Everything is public, and is either a List<> or basic data type, and all classes have the [Serializable] tag. Is there anything else I can try?

2

I think it’s because you’re declaring the variable with a new List();

Instead, just simply declare the variable as such: public List m_nodes;

3

That seems to have worked. The error has shifted to a different area of code. It seems like everything is fine, but when I go into Play mode and come back, or close Unity and reopen it. It doesn’t properly reinstantiate my objects.

I am getting “NullReferenceException: Object reference not set to an instance of an object” at this line:

[Serializable]
public class RectangleF
{
    public float _x;
    public float _y;
    public float _width;
    public float _height;
    public float _x2;
    public float _y2;
}

[Serializable]
public class QuadTreeNode
{
    public List<QuadTreeNode> m_nodes;
    public RectangleF m_bounds;

    public RectangleF GetBounds() { return m_bounds; }
}

[Serializable]
public class TerrainScript : MonoBehaviour 
{
    public void CreateGeometry(QuadTreeNode obj)
    {
            if (obj.GetEnabled())
           {
                vertices[m_CurrentVertex].x = obj.GetBounds().X; (exception here only after play/continue or unity open/close)
             }
    }
}

I’ve been looking into Serialization. Is [Serializable] all I need to add to make my own classes serializable for use in the Unity Editor?

Any help greatly appreciated.