Chimera Commands Index
roll [ axis [ angle [ frames ]]]
[ models model-spec ]
[ coordinateSystem N ]
[ center center ]
[ precessionTilt tilt ]
Roll rotates the models by angle degrees
(default 1.5) around a specified axis (default y)
for a specified number of frames (default infinity).
Roll is the same as turn except
for the default number of frames. See also:
The angle can be positive or negative.
The models to rotate 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 rotated.
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:
The center 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
- z - Z-axis (if laboratory coordinate system, perpendicular to the screen)
(three values separated by commas only) - an arbitrary vector
- axisID - the identifier of an axis defined with
or the define command;
object IDs are listed in the
- 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
will be used for reference frame pinning unless
a center atom-spec
or a coordinateSystem is also given.
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.
(three values separated by commas only) - an arbitrary point
- an atom-spec
of any combination of atoms and
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:
This does not change the current
center of rotation method,
but allows using a different one for the purposes of executing the command.
- view (center of view method)
- models (center of models method)
- front (front center method)
The precessionTilt option specifies an additional rotation
about a moving axis that is carried along by the main rotation.
The moving axis is offset from the main axis by tilt degrees
(toward the vertical if axis is along the line of sight).
The two rotations cycle at the same rate
but in opposite directions around their respective axes.
Wobble motion movie
in the Chimera Animation Gallery.
Keyword options can be used in any order and the keywords can be truncated.
roll 1,1,0 center 8.5,0,0 coord #1
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 roll,