-------------------------------------------
var,funct: load surface (topology must match startup)
  set insurf <surface>
  read_binary_surface
-------------------------------------------

Large Panel Only: [fn-]F3

The "insurf:" entry at the upper left (large
fn-F3 panel only) contains editable name used for
reading/reloading a surface using the "R" button
to the right.  The entry shows the full filename
of the current surface (not just suffix like the
"surf:" entry on the F2 panel).

To load a different surface for the current
subject and hemisphere, type its name in the
entry and click "R".  An invalid entry will
reload the initial surface.

The standard location for surfaces is:

  $SUBJECTS_DIR/<subjname>/surf/$hemi.$surfext

This entry accepts the following variations in
the pathname for a left hemisphere orig surface:

  lh.orig               ;# in $SUBJECTS_DIR/$subject/surf
  ~/surf/lh.orig        ;# '~' globs to current subject
  /full/path/to/lh.orig ;# absolute path

The new surface must have the same number of
vertices and faces as the surface tksurfer was
started up with.  The current surface pose,
magnification, and statistical overlay data (if
any) are preserved.

This entry uses the C/tcl function:

  read_binary_surface

to read the current surface filename in the tcl/C
variable, $insurf.  The function can read native
freesurfer triangular or quadrangular surfaces in
binary or ASCII format.  A number of other
surface formats are also auto-detected and
readable by this function:

  native FreeSurfer tri or quad: (binary)
  native FreeSurfer tri or quad: (ASCII)
  ICO tri: FreeSurfer icosahedral (ASCII)
  VTK tri: visualization toolkit format (ASCII)
  OFF tri: object file format (ASCII)
  GIFTI tri: NIFTI surface format (base64 ASCII)
  OBJ tri: Alias Wavefront (ASCII)
  SRF tri: Brain Voyager (binary)

If the tksurfer start-up surface is a triangular
surface, it can't be updated/changed to a
same-vertex-count quadrangular surface (can't
know which edges to remove) using this entry.
The reverse, however works (startup with quad
surface, update with same-vertex tri surface).

Since *.srf surfaces have left-handed coordinates
(PIL vs. freesurfer RAS coordinates), they will
appear mirror-imaged in tksurfer (a right hemi
will look like a left hemi, and vice versa, and
you will get a warning panel the first two times
you open the surface).  The surface coordinates
can be mirror-imaged (e.g., in order to save the
surface as a native freesurfer surface) with
"FlipHemi" at the middle-upper right of the
larger F3 interface (this flips the sign of the
x-coordinate).

See R-click help for the upper-left "surf:" entry
for details of readable surface file formats.
