Re: [Update REQ 5442]: camera motion and maniview

["Stuart Levy" <slevy>]

The way maniview (actually Charlie Gunn's discrete-group code inside
geomview) does camera centering is to alter the position of the camera
inside the geomview drawing loop, so that it will be correctly placed
the *next* time the view is drawn.  This works well if the camera is moving
in a series of small, relative steps as it often does in interactive
motions.  But when you specify the camera's position explicitly for each
frame, the re-centered camera position never gets used for drawing.

You could force geomview to redraw after computing the new position,
though, by saying:

  (xform-set <whatever-camera>  <transform1>)
  (redraw <whatever-camera>)
  (xform-set <whatever-camera>  <transform2>)
  (redraw <whatever-camera>)

The result might be unattractive, though, since you'll alternately see
views drawn from raw and recentered camera positions.  I think there may
be no way to avoid that.