Motion Blending #

When layering motions, the movements specified by multiple motions can conflict. For example, in the example on the “Motion Layer” page, when blending a walking motion with a one-hand wave motion, the character’s right arm bone receives both the arm-swing from walk.vmd and the arm-raise/side-to-side motion from onehandwave.vmd.

This section explains how to resolve such overlapping motions.

Replace, Add, Multiply #

The default behavior for overlaps is “replace”. In other words, the motion with the highest priority is used and lower-priority motions are ignored. Priority is determined by start time: the most recently started motion has the highest priority. In the example, the side-to-side motion from onehandwave.vmd took precedence over the walk.vmd motion.

You can change this overlap behavior by issuing a MOTION_CONFIGURE message after adding a motion. The available modes are:

MODE_REPLACE: Replace (overwrite)
MODEL_ADD: Additive
MODEL_MUL: Multiply (morphs only)

The default MODE_REPLACE overwrites lower-priority motions. Specifying MODEL_ADD will add this motion’s movement to the lower-priority motion’s movement. MODEL_MUL multiplies the morph amount calculated by the lower-priority motion by the morph values indicated by this motion.

MOTION_CONFIGURE|(model)|(motion)|MODE_REPLACE
MOTION_CONFIGURE|(model)|(motion)|MODE_ADD
MOTION_CONFIGURE|(model)|(motion)|MODE_MUL

As an example use case, additive mode can be used to add subtle jitter or offsets, similar to MMD’s “multi-stage bone” setups. Multiply can be used to disable part of a lower-priority motion’s morph changes by specifying 0, for instance.

Blend Rate #

In addition to the above mode, you can set a blend rate per motion. The value ranges from 0.0 to 1.0; the default is 1.0.

MOTION_CONFIGURE|(model)|(motion)|MODE_REPLACE|(rate)
MOTION_CONFIGURE|(model)|(motion)|MODE_ADD|(rate)
MOTION_CONFIGURE|(model)|(motion)|MODE_MUL|(rate)
MOTION_CONFIGURE|(model)|(motion)|BLEND_RATE|(rate)

When layering, the blend rate is multiplied into the motion before performing the replace/add/multiply operation. Concretely:

MODE_REPLACE + rate: the motion’s movement is multiplied by rate and then used to replace the lower-priority movement
MODE_ADD + rate: the motion’s movement is multiplied by rate and then added to the lower-priority movement
MODE_MUL + rate: the change indicated by this motion is multiplied by rate and then used to multiply the lower-priority morph values

You can also use BLEND_RATE to change only the rate value without changing the mode.

Per-bone control #

The above applies to entire motions, but you can also configure these settings in detail on a per-bone basis. See the reference for details.