# RegionSegment struct

Namespace: [Grasshopper2.Types.Shapes](https://developer.rhino3d.com/api/gh2/namespace/grasshopper2.types.shapes.md) · Assembly: [Grasshopper2](https://developer.rhino3d.com/api/gh2/assembly/grasshopper2.md)

```cs
public readonly struct RegionSegment
```

One piece of a rolling-ball region boundary: a trimmed input curve or a fillet arc.

## Properties

- [Fillet](https://developer.rhino3d.com/api/gh2/type/grasshopper2.types.shapes.regionsegment/fillet.md): The fillet arc, unset for an original piece.
- [Geometry](https://developer.rhino3d.com/api/gh2/type/grasshopper2.types.shapes.regionsegment/geometry.md): The curve of this segment; a trimmed input curve or an arc.
- [IsFillet](https://developer.rhino3d.com/api/gh2/type/grasshopper2.types.shapes.regionsegment/isfillet.md): Whether this segment is an arc swept by the ball rather than part of an input curve.
- [SourceCurve](https://developer.rhino3d.com/api/gh2/type/grasshopper2.types.shapes.regionsegment/sourcecurve.md): Index of the input curve this segment was cut from (outer boundary first, then its holes), or -1 for a fillet.
- [SourceDomain](https://developer.rhino3d.com/api/gh2/type/grasshopper2.types.shapes.regionsegment/sourcedomain.md): Parameter interval of the input curve this segment covers, unset for a fillet.
- [TouchesA](https://developer.rhino3d.com/api/gh2/type/grasshopper2.types.shapes.regionsegment/touchesa.md): Index of the input curve the ball touches at the start of a fillet.
- [TouchesB](https://developer.rhino3d.com/api/gh2/type/grasshopper2.types.shapes.regionsegment/touchesb.md): Index of the input curve the ball touches at the end of a fillet.