private static extern PluginError zcuCalculateFrustumDisparity( IntPtr frustumHandle, ZSVector3 point, out float disparity);
private static extern PluginError zcuGetFrustumCameraOffset( IntPtr frustumHandle, out ZSVector3 cameraOffset);
private static extern PluginError zcuGetFrustumEyePosition( IntPtr frustumHandle, Eye eye, CoordinateSpace coordinateSpace, out ZSVector3 eyePosition);
private static extern PluginError zcuSetFrustumCameraOffset( IntPtr frustumHandle, [param: MarshalAs(UnmanagedType.LPStruct)] ZSVector3 cameraOffset);