For the complete documentation index, see llms.txt. This page is also available as Markdown.

Body language

Find guides for adding ambient posture, breathing, weight shifts, and small reactive movements that keep a Convai character's body alive between animations.

Body Language is the Convai embodiment module that gives a character continuous, ambient nonverbal behavior: breathing, weight shifts, small gestures, and reactive flinches that never stop between authored actions. Body Animation plays authored clips — a walk cycle, a wave — and Body Language never owns a clip; it only adds small procedural motion on top of whatever the character is already doing. One component, ConvaiBodyLanguageController, drives all of it.


What body language gives a character

Behavior
What it looks like

Breathing

The chest and shoulders expand and contract on a continuous cycle, with occasional sharper intakes on interruption, a settling sigh, and a deeper breath before the character starts speaking.

Weight shifts and sway

The character periodically transfers its weight between feet and drifts gently on the spot, the way a standing body constantly micro-balances rather than holding perfectly still.

Gesticulation

While speaking, small head beats and posture pulses ride the character's speech rhythm, and its hands stay subtly alive between authored gestures instead of sitting rigid.

Listening posture

While listening, the character leans in slightly and settles into stillness, with an occasional attentive head tilt.

Fidgets

While idle or thinking, a slow lateral weight shift keeps the character from looking frozen.

Reactions

A sudden emotion spike — surprise, amusement — can trigger a one-shot startle flinch or an amused bounce.

Add ConvaiBodyLanguageController to a character through Convai > Embodiment > Body Language and it works immediately on the SDK's built-in tuning — no profile asset is required to see breathing and weight shifts in Play mode.


How it differs from body animation

Body Animation and Body Language both move the character's skeleton, but they solve different problems and never fight over the same motion:

Body Animation
Body Language

What it plays

Authored clips: idles, walk cycles, talk overlays, actions, pointing

No clips at all — continuous procedural motion computed every tick

What it owns

The character's locomotion and any deliberate, recognizable motion

Ambient life layered on top: breathing, weight shift, posture, small gestures

How the two combine

Plays its clip through the PlayableGraph as usual

Adds small, swing-only deltas on top of whatever Body Animation already posed

A character can carry either module alone, or both together. When both are present, Body Language reduces itself rather than overriding Body Animation — see How body language works for the suppression rule that makes this coexistence reliable.


Where to start

Body language quick start

Explore body language

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