---
title: centerOfMass
framework: realitykit
role: symbol
role_heading: Instance Property
path: realitykit/physicsmassproperties/centerofmass
---

# centerOfMass

The position of the center of mass and the orientation of the principal axes.

## Declaration

```swift
var centerOfMass: (position: SIMD3<Float>, orientation: simd_quatf)
```

## Discussion

Discussion The position defines the center of mass with a default value of (0, 0, 0), which means that the local origin of the model is the center of mass. The orientation defines the principal axes, such the inertia matrix is a diagonal.

## See Also

### Getting mass properties

- [mass](realitykit/physicsmassproperties/mass.md)
- [inertia](realitykit/physicsmassproperties/inertia.md)