private void OnDestroy()
        {
            m_tool = null;

            if (m_terrainBrushEditor != null)
            {
                m_terrainBrushEditor.SelectedBrushChanged -= OnSelectedBrushChanged;
                m_terrainBrushEditor.BrushParamsChanged   -= OnBrushParamsChanged;
            }
        }
 private void Awake()
 {
     m_terrainBrushEditor.SelectedBrushChanged += OnSelectedBrushChanged;
     m_terrainBrushEditor.BrushParamsChanged   += OnBrushParamsChanged;
     m_tool = IOC.Resolve <ITerrainAreaTool>();
 }