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- Enforce Defaults:
Choose between three states: ON, OFF and ONLY MESH / MEDIA:

In Pandora's Box timeline programming you normally determine the value of a parameter by setting a key. In some situations, however, a certain parameter may not have a key associated with it that explicitly determines its value at a certain point in time. For those situations the system can be set to "enforce defaults", i.e. to ensure that the parameter in question has the default value even though the default value is not explicitly set (by key) in the timeline.

There are two "default situations". First, the points in time in the "empty space" between clips (figure 1a). Second, the points in time to the left of the first key in a clip for a particular parameter (figure 1b). In both of these situations, there are some parameters that the system can not associate with a key.

figure 1a: empty space between clips

_img209figure 1b: left of a first key in the clip

If Enforce Defaults is ON then the system will automatically apply default values to the parameters in default situations. This behavior ensures that each frame in the timeline is associated with exactly one definite state for all parameters. So if you click into the timeline at TC 0:00:09:00, for example, then jump to other places in the timeline and return to TC 0:00:09:00 later, the output will be exactly the same as before at TC 0:00:09:00, even though you may not have explicitly set values for all the parameters.

If Enforce Defaults is OFF then the system does not apply defaults in the situations described above. Rather, the parameters retain whichever value was set before the situation was encountered. This means that the state associated with a particular frame in the timeline depends on two things.

All parameters which have explicitly set keys are changed to reflect those keys. The values of the remaining parameters, however, are not changed at all (since defaults are not being enforced). The state of the output therefore depends in part on how the parameters for which no keys were explicitly set were edited before.

To see this, take a look at figures 2, 3a and 3b. At the beginning of the first clip, the scale of the object is explicitly set by a key.
Imagine the timeline is started at TC 0:00:09:00 and runs on until it is paused at TC 0:00:18:00.

figure 2: Enforce Defaults is set to ON

figure 3a: Enforce Defaults is set to OFF; the scaling keys of the first clip have very low values

figure 3b: Enforce Defaults is set to OFF; the scaling keys of the first clip have very high values

The state of the output when Enforce Defaults is OFF is "path dependent" in the sense that it depends on the "path" you take to reach a particular timeline frame. When Enforce Defaults is ON it is "path independent" in that the output state depends only on the frame that you are in.

Take a look at figure 4 and 5 for an example of path dependency when Enforce Defaults is set to OFF. Consider a user clicking in the timeline at the different timecodes.

figure 4: Enforce Defaults is set to OFF.
Jumping from TC 0:00:09:00 (low values for object scale) to TC 0:00:18:00 (no scaling values) results in an object that is scaled very small.

figure 5: Enforce Defaults is set to OFF
Jumping from TC 0:00:09:00 (low values for object scale) over TC 0:00:27:00 (high values for object scale) to TC 0:00:18:00 (no values for object scale) results in an object that is scaled very high.

Path independence means that leaving Enforce Defaults set to ON is usually a good idea, especially when working with a single timeline, since it helps you make sure that each frame in the timeline leads to exactly the result you want it to. When working with multiple timelines, however, you may want to use one timeline to control certain parameters of a device while using a different timeline to control other parameters of the same device. In this and similar scenarios, it is necessary for each timeline to only apply those values that are explicitly set in it via keys. This gives the other timelines the needed "space" to apply the values determined by their keys.

In these cases, setting Enforce Defaults to OFF makes sure that each timeline yields as much as possible to other timelines.

Note that you can use the inspector of a media or mesh assignment key to set the value of the key to "none". This allows you to unload mesh or media from layers even when Enforce Defaults is set to OFF by explicitly applying the default value ("none") via a key.

The setting ONLY MESH / MEDIA combines aspects of both of the other two Enforce Defaults modes. When it is set defaults are automatically applied to the mesh and media parameters. All other parameters besides mesh and media are not changed at all in the default situations.