How do I fix a StackOverflowException?

Question

I am getting a StackOverflowException in my C# program.

Cmodel.cs

public class CModel
{
    public Vector3 Position { get; set; }

    public Vector3 Rotation { get; set; }

    public Vector3 Scale { get; set; }

    public Model Model { get; private set; }

    public BoundingSphere BoundingSphere
    {
        get
        {
            // no need for rotation, as this is a sphere
            Matrix worldTransform = Matrix.CreateScale(Scale) *
            Matrix.CreateTranslation(Position); // THIS IS WHERE THE EXCEPTION OCCURS

            BoundingSphere transformed = BoundingSphere;
            transformed = transformed.Transform(worldTransform);

            return transformed;
        }
    }
    private Matrix[] modelTransforms;
    private GraphicsDevice graphicsDevice;
    private BoundingSphere boundingsphere;
    public CModel(Model Model, Vector3 Position, Vector3 Rotation,
    Vector3 Scale, GraphicsDevice graphicsDevice)
    {
    this.Model = Model;

    modelTransforms = new Matrix[Model.Bones.Count];
    Model.CopyAbsoluteBoneTransformsTo(modelTransforms);

    buildBoundingSphere();
    }


    public void Draw(Matrix View, Matrix Projection)
    {
        // Calculate the base transformation by combining
        // translation, rotation, and scaling
        Matrix baseWorld = Matrix.CreateScale(Scale)
        * Matrix.CreateFromYawPitchRoll(
        Rotation.Y, Rotation.X, Rotation.Z)
        * Matrix.CreateTranslation(Position);
        foreach (ModelMesh mesh in Model.Meshes)
        {
            Matrix localWorld = modelTransforms[mesh.ParentBone.Index]
            * baseWorld;
            foreach (ModelMeshPart meshPart in mesh.MeshParts)
            {
                BasicEffect effect = (BasicEffect)meshPart.Effect;
                effect.World = localWorld;
                effect.View = View;
                effect.Projection = Projection;
                effect.EnableDefaultLighting();
            }
            mesh.Draw();
        }
    }
        private void buildBoundingSphere()
        {
            BoundingSphere sphere = new BoundingSphere(Vector3.Zero, 0);

            // Merge all the model's built in bounding spheres
            foreach (ModelMesh mesh in Model.Meshes)
            {
                BoundingSphere transformed = mesh.BoundingSphere.Transform(
                    modelTransforms[mesh.ParentBone.Index]);

                sphere = BoundingSphere.CreateMerged(sphere, transformed);
            }

            this.boundingsphere = sphere;
        }
    }
}

Answer 1

You have a recursive call in your getter which will call itself and cause the StackOverflowException :

public BoundingSphere BoundingSphere
{
    get
    {
       ...
       BoundingSphere transformed = BoundingSphere;
       ...
    }
}

It's not completely clear what you meant to write - but if you want to preserve any state you will need a backing field for storing the bounding sphere instead.

Answer 2

1. Look at the call stack or the exception's stack trace.
2. Identify the loop.
3. Figure out how to break the loop.

Answer 3

Your get method calls itself: BoundingSphere calls BoundingSphere.

private BoundingSphere _boundingsphere = null;
public BoundingSphere BoundingSphere
{
    get
    {
        // no need for rotation, as this is a sphere
        **Matrix worldTransform = Matrix.CreateScale(Scale)
            * Matrix.CreateTranslation(Position);**

        BoundingSphere transformed = _boundingsphere;
        transformed = transformed.Transform(worldTransform);

        return transformed;
    }
    set
    {
        _boundingsphere = value;
    }
}

When you use following form:

public BoundingSphere BoundingSphere { get; set }

you don't need to specify variable to store actual value, but when you implement get or set explicitly you should declare additional variable and use it in get, set implementations.

Answer 4

I think you're needing to change

get 
{ 
    ...
    BoundingSphere transformed = BoundingSphere; // public property
    ...
}

to this

get 
{ 
    ...
    BoundingSphere transformed = boundingsphere; // private variable
    ...
}