Tip #3, Regular vs. Time-Independent Groups

On a related note, Flash (the authoring tool and SWF format) doesn't have an exact match for LM's concept of groups as containers that can be animated and transformed like other objects. Therefore LM must break apart its groups when it exports, writing transformation info for each item. One exception to this is time-independent groups, which LM exports as Flash movie clips. By giving each member of a group only the transformations unique to it, and by applying the common transformations at the time-independent group level, you can save significant file size.

To understand the file size implications, make ten objects, animate their scale over 1 second, then group them and animate the rotation of the group. Export and note the file size. Now select the group and from the Timeline menu choose Time Independent (see movie below). Export and note the new file size. In my test I save 1.5kb. The more frames, objects, and attributes I use, the more the file size savings increases.

You can get dramatic savings when you duplicate groups and make sure they're set to be time independent (see movie below). On export LM will wrap the contents in a Flash movie clip, and if the contents and transformations are identical (see below), it will recognize that they're the same and will re-use the contents.

So should you always use time-independent groups? If you're doing strictly linear animation, probably so. Remember, though, that if you stop the main timeline, TIGs will continue to play unless you add a behavior that targets and stops them. You also won't be able to see their contents moving in the editing environment, though it's easy to change the time independent setting back and forth as you work.