From: John Stone (
Date: Mon Sep 08 2014 - 09:55:55 CDT

You cannot change the selection on write, otherwise you would get a
trajectory with a scrambled combination of atom indices. The most
commonly used trajectory formats do not allow the set of atoms written
in subsequent frames to be changed -- they must remain consistent
for the length of the entire trajectory. There are a couple of
file formats that do allow different per-frame atom sets to be written,
but they are currently in the extreme minority.

  John Stone

On Sun, Sep 07, 2014 at 10:43:05PM -0600, Eric Smoll wrote:
> Hello VMD users,
> Under "graphics -> representations", the trajectory tab has a option to
> "update selection every frame". From the terminal, I believe this can be
> accomplished with with command "mol selupdate 0 0 on".A
> When i use "animate write $TYPE $FILETYPE sel $SEL" on a selection, the
> selection is not updated. I assume the output atoms are those captured
> when the selection is set. "mol selupdate 0 0 on" does not seem to impact
> the output of "animate write." How can I update my selection for every
> frame output by "animate write"?
> -Eric

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