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

# useSitePosition

> Track MuJoCo site world position and orientation

Returns refs tracking a MuJoCo site's world position and orientation. Useful for tracking end-effectors, sensors, or reference frames.

## Signature

```tsx theme={null}
useSitePosition(siteName: string): {
  position: React.RefObject<THREE.Vector3>;
  quaternion: React.RefObject<THREE.Quaternion>;
}
```

## Usage

```tsx theme={null}
import { useSitePosition } from "mujoco-react";

function TCPTracker() {
  const { position, quaternion } = useSitePosition("tcp");

  useFrame(() => {
    console.log("TCP at:", position.current.toArray());
  });

  return null;
}
```

### Visual Marker at Site

```tsx theme={null}
function SiteMarker({ siteName }: { siteName: string }) {
  const { position } = useSitePosition(siteName);
  const ref = useRef<THREE.Mesh>(null);

  useFrame(() => {
    ref.current?.position.copy(position.current);
  });

  return (
    <mesh ref={ref}>
      <sphereGeometry args={[0.01]} />
      <meshStandardMaterial color="red" />
    </mesh>
  );
}
```

## Return Value

| Field        | Type                          | Description                                                       |
| ------------ | ----------------------------- | ----------------------------------------------------------------- |
| `position`   | `RefObject<THREE.Vector3>`    | World position from `data.site_xpos`                              |
| `quaternion` | `RefObject<THREE.Quaternion>` | World orientation from `data.site_xmat` (converted to quaternion) |

## Notes

* Updated every frame via `useAfterPhysicsStep`
* Returns refs, not state — no re-renders
* The site must exist in the MuJoCo model