Actions are packages of low-level animation, such as function curves, expressions, constraints, and linked parameters. By creating a package that represents the animation, you can work at a higher level of animation that is not restricted by time. You can move an action around anywhere in time, squeeze or stretch its length as you like, apply one action after another in sequences, and mix two or more actions together to create a new animation.
Actions are animation segments that you create once and apply as many times as you like. You can create an entire library of actions, like walk cycles or jumps, and share them among any number of models. After you create an action, you load it as a clip in the animation mixer, where you can modify the animation in a nonlinear and non-destructive way.
You can also create compound actions that are “containers” for multiple actions, including animation from different sources (function curves, expressions, constraints, and linked parameters). Working with complex animation data becomes a simpler task than dealing with multiple fcurves.
|
Actions in XSI are not the same as those in SOFTIMAGE|3D, where they are elements within .ani files. In XSI, actions are separate elements. |
Because actions package animation data into a single usable unit, it makes it easy to copy animation from one model to another, even if the model doesn’t share the same hierarchy, scale, or naming conventions. When there are differences between the models, a template opens to help you map the corresponding model elements.
Actions are associated with the models in your scene, which provide a way of organizing the objects in a scene (like a mini scene). They contain not just the geometry of hierarchies, but also the function curves, shaders, and other properties that have been applied to it, including actions. Models also make it easier to share actions and mixer information between characters.
For more information on using models with the mixer in general, see Models and the Mixer; for information on using models specifically for sharing animation, see Sharing Actions between Models.
Actions and Other Animation on an Object
Actions let you combine animation from different sources, acting like a container or package. When a parameter is driven by a clip at a given frame, the animation values determined by the mixer take precedence over any other type of animation. The mixer reads from and writes to a virtual region above any existing fcurves or expressions at the scene level, but below any constraints at the scene level.
Basically, action clips override any other animation for the object at that frame. You can, however, have fcurves on an object (at the scene level) and mix them with an action clip over the same frames if you select an option in the Mixer Properties. For information on this, see Mixing Fcurves with Action Clips.
If there is no animation on the object between clips, the animation value of the last frame of the last clip remains active until the next clip.
Between clips, the parameter is driven by whatever animation is going on in the “background.” Even on frames where a parameter is driven by an action, you can still adjust values and set keys to define the background animation. You can also use a fill action to set the background animation—see Filling the Gaps between Action Clips.
How Do You Share the Animation?
There are a number of ways in which you can share animation between models, whether they are in the same scene or a different scene:
• Copy action clips and compound clips (which lets you combine a number of clips non-destructively) between models. See Copying Clips for more information.
• Copy action sources and compound sources between models in the same scene. See Copying Action Sources between Models for more information.
• Save an action source as a preset to copy action sources between models in different scenes. See Creating Action Source Presets for more information.
• Create an external action source in a separate file in different formats (.xsi or .eani) to be used in other XSI scenes. See Creating External Action Sources for more information.
• Import and export action sources in different file formats to be used in other scenes or other software packages. See Importing and Exporting Action Sources for more information.
• Import and export a model’s animation mixer as a preset to copy it to models in the same scene or another scene. See Importing and Exporting the Animation Mixer for more information.
SOFTIMAGE|XSI v.6.01