public RiverPoint GetClosestRiverPointTo(Vector2 aPosition)
    {
        RiverPointQuadTree smallestQuadtree = GetSmallestQuadtreeAt(aPosition);
        RiverPointQuadTree currentlyExplored = smallestQuadtree;

        RiverPoint closestPoint = null;

        smallestQuadtree.ExploreNode(aPosition, ref closestPoint); //initial condition : search for closest point in smallest quadtree

        while (currentlyExplored.myParent != null)  //while current != root
        {
            currentlyExplored = currentlyExplored.myParent;
            currentlyExplored.ExploreNode(aPosition, ref closestPoint);
        }

        return closestPoint;
    }

    protected void ExploreNode(Vector2 aPoint, ref RiverPoint aClosestPoint)
    {
        if (myHasChildren)
        {
            for (int i = 0; i < 2; ++i)
                for (int j = 0; j < 2; ++j)
                {
                    float distanceToChild = myChildren[i, j].GetSquaredDistanceOfPointToNode(aPoint);
                    if (distanceToChild >= 0f)   //Point not inside of that node (should have been explored already)
                    {
                        if (aClosestPoint == null)
                        {
                            myChildren[i, j].ExploreNode(aPoint, ref aClosestPoint);
                        }
                        else
                        {
                            if (distanceToChild < (aPoint - aClosestPoint.myPosition).sqrMagnitude) //Only explore nodes that could have closer points
                            {
                                myChildren[i, j].ExploreNode(aPoint, ref aClosestPoint);
                            }
                        }
                    }
                }
        }
        else
        {
            for (int i = 0; i < myPoints.Count; ++i)
            {
                if (aClosestPoint == null)
                    aClosestPoint = myPoints[i];
                else
                {
                    if ((aPoint - myPoints[i].myPosition).sqrMagnitude < (aPoint - aClosestPoint.myPosition).sqrMagnitude)
                        aClosestPoint = myPoints[i];
                }
            }
        }
    }

    protected float GetSquaredDistanceOfPointToNode(Vector2 aPoint)
    {
        if (IsPointInQuadtree(aPoint))
            return -1f;
        else
        {
            float cx = Mathf.Clamp(aPoint.x, myTopLeft.x, myBottomRight.x);// Mathf.Max(Mathf.Min(aPoint.x, myBottomRight.x), myTopLeft.x);
            float cy = Mathf.Clamp(aPoint.y, myTopLeft.y, myBottomRight.y); //Mathf.Max(Mathf.Min(aPoint.y, aBottomRight.y), ry);
            return (aPoint.x - cx) * (aPoint.x - cx) + (aPoint.y - cy) * (aPoint.y - cy);
        }
    }