Docs / Reference / Glossary & units
Glossary & units
The terms this documentation uses, plus the unit and axis conventions behind them.
| Term | Meaning |
|---|---|
| MMCP | The Motion MCP protocol the plugin speaks to the server. The plugin is a client; the server generates. |
| Canonical skeleton | A rig in the layout the model expects. Create Skeleton builds one — soma77, 77 joints, rooted at Hips. Rigs of your own go on the wire as they are and are retargeted server-side. |
| Adopt | Make a rig you already have pipeline-ready — store its current pose as the bind pose, plus hip height and namespace — without marking it canonical. |
| Namespace | The prefix on created joints (default animatica), which keeps several rigs in one scene apart. |
| Constraint / pin | One authored requirement at one frame: a pose shape, an effector position, or a path waypoint. Pins appear on the timeline; markers appear in the viewport. |
| Path (root2d) | A sequence of ground waypoints saying where the character should be, and when. |
| Diffusion steps | How much effort the model spends. More steps is better and slower; the server caps them at 500. |
| Replace | 3ds Max holds one animation, so a generation replaces it. This is the only output mode here, which is why no mode picker is shown. |
#Units & axes
The protocol boundary is fixed at meters, right-handed Y-up. 3ds Max is Z-up, and its scene unit can be anything — both are converted for you in a single module, so nothing you do in the scene has to be expressed in the protocol's terms.
| Boundary | Convention |
|---|---|
| The wire | Meters, right-handed, Y-up |
| Your scene | Z-up, in whatever system unit the scene is set to |
| Both | Right-handed, so nothing mirrors on the way through |
Up on the wire, (0, 1, 0), lands on Max's +Z; the protocol's forward
basis, (0, 0, 1), lands on −Y, which is Max's conventional character
facing.
#The scene unit is read, not assumed
The scale is asked of the scene at runtime rather than hardcoded, because Max's default system unit is inches: one meter measures 39.370079 system units in a default scene. Reading the system unit type alone would not be enough either, since the system scale multiplies it — so the plugin asks the scene to decode one meter and uses the number it gets back.
That answer is cached and dropped again whenever the scene's units change. Changing the system unit mid-session does not rescale geometry that already exists, so the new scale applies to what is written after the change. It is not a migration of what is already in the scene.
#Frame rate
Motion is generated at the model's native 30 fps. Turn on Match scene FPS in Settings to have it keyed at your scene's rate instead.