public Matrix GetCameraMatrix ( StereoEye stereoEye )
{
if (stereoEye==StereoEye.Mono) return cameraMatrix;
if (stereoEye==StereoEye.Left) return cameraMatrixL;
if (stereoEye==StereoEye.Right) return cameraMatrixR;
throw new ArgumentException("stereoEye");
}