First go to User Preferences->Addons and enable the TimeOffset
addon in the Object category.
Activate it (button in the Mesh Tools panel).
Get all the objects you want to be grouped/offset and make them children of
an EMPTY object.
This will be your root object
which you can select in the pulldownmenu that lists all the empties
in the scene.
Make copies of your empty + children using either Alt+D or Shift+D...
Theres two ways the addon can identify duplicates, either by Name or by
Instance. The second
one can only be used when you only used Alt+D for duplicating, then the
addon can check if the
objects' data is the same for the instances and the root and as such
identify the duplicates. When
using Shift+D youll have to tick the "byName" tickbox, then the addon will
select all objects that
have the name of the root empty as part of their empty name, so if root is
named "base", empties
named "base.001", "second_base" will be selected.
Click "Set Root Object" whenever you feel like it and all duplicates will be
listed with a slider for
their individual frame offset values.
You can set multiple objects to the same value by setting the "Value" and
clicking "Selected to":
selected objects (any child of or the empty itself) will be set to this
offset value.
Also when you want to set a number of objects to an increasing or decreasing
interval
of offset values, then you can set the "Start" and "Interval" values and
click "Selected to:" above it.
Take care, TimeOffset will set intervals according to the order
in which objects were selected, and
this selection should be done after
activating the addon... everything selected before will be ordered
alphabetically instead.
You can randomize these values by choosing Lower and Upper limits for the
values and then clicking
"Randomize". Also when adding new empties later these will be
automatically added to the duplicate
list!
When using many duplicates, Blender might slow down a lot, to circumvent
this select the
"Only Render" tickbox, then offsets will only be applied when rendering and
not when playing the
animation in the viewport.
Another method, and what you should do when everything is setup to your
liking, is clicking
"Apply", when doing this, the addon will bake all animation offsets into the
individual object
animation curves : takecare! this does severe the instance links between
Alt+D instances!
Still you can go back to the offset addon by re-activating it (instance
links will remain broken
though...) All settings are saved with the .blend file.