> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cyberwave.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Fixed and Free-Floating Objects

> Decide whether a procedural object stays put or moves under physics in simulation.

<Note>This page is a stub. A human will curate and expand it before publishing.</Note>

Every procedural object you place — a wall, a rack, a crate — is either **fixed
base** (welded to the world) or **free base** (a physical body that falls under
gravity and can be pushed).

## Where to set it

Select the object in the environment editor. The right-hand panel has a
**Physics** section with a **Fixed base** switch:

* **On** — the object stays exactly where you placed it, no matter what hits it.
* **Off** — the object is simulated: it drops onto whatever is beneath it, and
  robots or other objects can move it.

**Reset** puts it back to the default for that kind of object. Fixtures (walls,
racks, floors, tables) default to fixed; loose objects (boxes, spheres,
cylinders, pallet stacks, carts) default to free.

## What changes in simulation

* A **free** object gets a free joint in MuJoCo, so it obeys gravity and
  contacts. Its live pose is streamed back, and the 3D scene follows it.
* A **fixed** object is welded to the world. Its pose is a constant, so nothing
  is streamed for it.
* The editor's own physics preview follows the same setting once you enable the
  physics toggle in the viewport.

## Things worth knowing

* **A freed fixture is still heavy.** Freeing a concrete wall or a loaded pallet
  rack is allowed, and it will topple or slide once the simulation starts.
* **Very thin objects cannot be freed usefully.** A marker with essentially no
  volume has no mass to simulate, so it stays welded — the editor warns you when
  this happens.
* **The setting sticks.** Switching an object to a different template keeps your
  choice; use **Reset** if you want the new template's default instead.

## Setting it from an agent

`cw_create_procedural_primitive` takes a `fixed_base` argument, and
`cw_edit_environment` can change it on an existing object. Leave it out to
inherit the default for that kind of object.