private void Awake()
    {
        //create an object and mesh for the trail
        trail = new GameObject("Trail", new[] { typeof(MeshRenderer), typeof(MeshFilter), typeof(PolygonCollider2D) });

        mesh = trail.GetComponent<MeshFilter>().mesh = new Mesh();
        trail.GetComponent<Renderer>().material = trailMaterial;

        //get and set the polygon collider on this trail.
        collider = trail.GetComponent<PolygonCollider2D>();
        collider.isTrigger = colliderIsTrigger;
        //trail.transform.parent = transform;

        //get the transform of the object this script is attatched to
        trans = transform;

        //set the first center position as the current position
        centerPositions = new LinkedList<Vector3>();
        centerPositions.AddFirst(trans.position);

        leftVertices = new LinkedList<Vertex>();
        rightVertices = new LinkedList<Vertex>();
    }

    private void Update()
    {
        if (!pausing)
        {
            //set the mesh and adjust widths if vertices were added or removed
            if (TryAddVertices() | TryRemoveVertices())
            {

                if (widthStart != widthEnd)
                {
                    SetVertexWidths();
                }

                SetMesh();
            }
        }
    }

    //************
    //
    // Private Methods
    //
    //************

    /// <summary>
    /// Adds new vertices if the object has moved more than 'vertexDistanceMin' from the most recent center position.
    /// If a pair of vertices has been added, this method returns true.
    /// </summary>
    private bool TryAddVertices()
    {
        bool vertsAdded = false;

        //check if the current position is far enough away (> 'vertexDistanceMin') from the most recent position where two vertices were added
        if ((centerPositions.First.Value - trans.position).sqrMagnitude > vertexDistanceMin * vertexDistanceMin)
        {
            Debug.Log("tray " + trans.position);
            //calculate the normalized direction from the 1) most recent position of vertex creation to the 2) current position
            Vector3 dirToCurrentPos = (trans.position - centerPositions.First.Value).normalized;

            //calculate the positions of the left and right vertices --> they are perpendicular to 'dirToCurrentPos' and 'renderDirection'
            Vector3 cross = Vector3.Cross(renderDirection, dirToCurrentPos);
            Vector3 leftPos = trans.position + (cross * -widthStart * 0.5f);
            Vector3 rightPos = trans.position + (cross * widthStart * 0.5f);

            //create two new vertices at the calculated positions
            leftVertices.AddFirst(new Vertex(leftPos, trans.position, (leftPos - trans.position).normalized));
            rightVertices.AddFirst(new Vertex(rightPos, trans.position, (rightPos - trans.position).normalized));

            //add the current position as the most recent center position
            centerPositions.AddFirst(trans.position);
            vertsAdded = true;
        }

        return vertsAdded;
    }