private void DestroyBuffers()
{
// LogManager.Instance.Write(string.Format("BillBoardSet.DestroyBuffers entered; vertexData {0}, indexData {1}, mainBuffer {2}",
// vertexData == null ? "null" : vertexData.ToString(),
// indexData == null ? "null" : indexData.ToString(),
// mainBuffer == null ? "null" : mainBuffer.ToString()));
this.vertexData = null;
this.indexData = null;
this.mainBuffer = null;
this.buffersCreated = false;
}