NAME
          DtCameraIsValid - Get the state of the valid bits for the
          given camera.


     SYNOPSIS
          #include <Dt.h>


          int  DtCameraIsValid( int cameraID, int valid_bit )


     DESCRIPTION
          DtCameraIsValid() returns 1 if none of the attributes of a
          camera indicated by cameraID have changed for the current
          frame, otherwise it returns 0.  The valid_bit parameter is
          used to check if any or all attributes of the camera have
          changed.  The following attributes can be checked to see if
          they have change from the previous frame:

          DT_CAMERA - if angle of the below attributes have changed.
          DT_CAMERA_POSITION - camera position has changed.
          DT_CAMERA_ORIENTATION - camera orientation has changed.
          DT_CAMERA_ASPECT - camera's aspect ratio has changed.
          DT_CAMERA_NEAR_CLIP - camera's near clipping plane has
          changed.
          DT_CAMERA_FAR_CLIP - camera's far clipping plane has
          changed.
          DT_CAMERA_FOCAL_DISTANCE - camera's focal distance has
          changed.
          DT_CAMERA_HEIGHT_ANGLE - camera's height angle has changed.
          DT_CAMERA_HEIGHT - camera's height has changed.

     Notes:  This is an obsolete routine.  Don't use.

     FILES
          Link with -lDtOMio