Chimera Commands Index
Usage:
rock [ axis [ angle [ frames ]]]
[ cycle frames-per-cycle ]
[ models model-spec ]
[ coordinateSystem N ]
[ center center ]
Rock wags the specified models back and forth
around a specified axis (default y)
for a specified number of frames (default infinity).
A full cycle of motion, analogous to a pendulum swing in one direction
and then the other, takes frames-per-cycle frames (default 136).
Larger values of frames-per-cycle will give a slower rocking motion.
See the
video mini-example.
See also:
roll,
turn,
select,
cofr,
set independent,
movie-related commands
The angle (default 3°) is 1/20 of the total angle
of rotation from one extreme to the other. It can be positive or negative,
corresponding to the initial direction of motion.
The models to rock can be specified by model number(s) or ranges
separated by commas and preceded by #. If no models are specified, all
active models will be moved.
A coordinateSystem can be specified by reference model number N,
optionally preceded by #.
Otherwise, the laboratory frame of reference will be used.
Any axis or center specification of the form x,y,z
will be interpreted in the reference coordinate system, and when further
motions are applied to an ongoing rotation, the center and axis will
remain pinned relative to the reference model.
The axis can be:
- x - X-axis (if laboratory coordinate system, horizontal in the plane
of the screen)
- y - Y-axis (if laboratory coordinate system, vertical in the plane of
the screen)
- z - Z-axis (if laboratory coordinate system, perpendicular to the screen)
- x,y,z
(three values separated by commas only) - an arbitrary vector
- axisID - the identifier of an axis defined with
Axes/Planes/Centroids
or the define command;
object IDs are listed in the
Axes/Planes/Centroids table
- an atom-spec of
exactly two atoms (not necessarily bonded or in the same model) or one bond.
If two atoms, the order of specification defines a handedness, and right-handed
rotations are positive. If a bond, the handedness is not under user control.
A bond can only be specified by selecting
it and using the word selected, sel, or picked;
any atoms also selected at the time will be ignored.
If a center is not specified separately,
it will lie on the atom-atom or bond axis.
If a separate center is supplied, only the direction of the axis will be used.
The first model in the axis
atom-spec
will be used for reference frame pinning unless
a center atom-spec
or a coordinateSystem is also given.
The center can be:
- x,y,z
(three values separated by commas only) - an arbitrary point
- an atom-spec
of any combination of atoms and
surface pieces.
The center of the bounding sphere of the specified items will be used.
The first model in atom-spec
will be used for reference frame pinning unless a coordinateSystem
is also given.
- any of the following keywords, to specify a
center of rotation method
for computing the center:
- view (center of view method)
- models (center of models method)
- front (front center method)
This does not change the current
center of rotation method,
but allows using a different one for the purposes of executing the command.
If a center of rotation is not specified directly or by using an
atom-spec to define
the axis, the current Chimera
center(s) of rotation will be used.
Keyword options can be used in any order and the keywords can be truncated.
Example:
rock z 5 136 center 0,0,0 coord 0
Commands continue to be processed while the requested motion is in progress.
To pause command processing until the motion is finished, use the
wait command. To halt an ongoing rock,
use freeze.