Secondary Motion

 

This feature improves animation generated by AutoPhysics by making it more smooth and accentuated.

Enabling Secondary Motion

This effect can be enabled or disabled by enabling or disabling the Secondary motion parameter. The parameter can be found on the Scene settings panel, under the AutoPhysics tab:

Applying Secondary Motion

Secondary Motion is generated automatically, but has to be manually snapped to the current animation.
To do this, click the Update torque Auto Physics button on the Toolbar, under the Auto Physics panel:

Muscle Stiffness

How much Secondary Animation impacts the character’s motion is defined by the Muscle Stiffness parameter.

This parameter can be found on the Object properties panel, under the Fulcrum point tab. It is specific to Point Controllers:

The parameter only affects the Main Point Controllers:

Here, the Main controllers are marked blue.

Muscle stiffness is set to 100 by default. At this value, the secondary animation will try to follow the original motion as close as possible.
To make the effect more noticable, the value has to be decreased. The following example shows Secondary Animation (applied to the character’s left hand) with Muscle Stiffness set to 99:

And with Muscle Stiffness set to 97 it would look like this:

This parameter can be animated. If you need secondary animation to only appear at certain moments, you can manually decrease Muscle Stiffness on the corresponding intervals.

Settings

A dedicated set of parameters for Secondary Motion behavior can be found on the Scene settings panel, under the Secondary Motion tab:

Instant restore
Controls instant pose restoration (how fast the character returns to the original pose).
The higher this value is, the shorter the secondary motion will be. If it is too high, the animation might end up distorted, so increasing this value should be done carefully.
Set to 0.1 by default.

Instant restore with the default value:

Increasing the value to 0.5 shortens the secondary animation significantly:

Cumulative restore
Controls additive pose restoration.
Increasing this value increases the effect that error (differences between secondary and original animation) have on the secondary animation.
Set to 0.001 by default.

Cumulative restore set to 0.001 (the default value):

Cumulative restore set to 0.01:

Interframe count
This parameter sets the number of subframes used for calculating Secondary Animation.

Increasing this value increases the stability of the effect.
Decreasing the value, on the other hand, decreases the impact on performance.

It is recommended to increase the value when Secondary Animation becomes distorted, and decrease it when the AutoPhysics simulation becomes too slow to work comfortably.
The default value is 10.

Example

An example of using Secondary Motion can be seen in the following video:

See Also

AutoPhysics

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