Function offset_wire 

pub fn offset_wire(
    model: &mut Model,
    wire: &Shape,
    offset: f64,
    join: Join,
    tol: Tolerances,
) -> OgeomResult<Built>

Offset a closed planar wire by offset: positive moves outward, away from the enclosed region, negative moves inward.

The wire’s edges must be straight or circular. Gaps at corners are closed per join; overlaps are trimmed to the pieces’ intersection. The history reports every input edge modified into its offset piece, every join generated from the corner vertex it replaces, and the wire modified into the result.

Errors

OgeomError::Construction if the wire is open or not planar, an edge is neither straight nor circular, the offset consumes an edge or an arc’s radius, an Intersection join is asked of a curved side, or the offset self-intersects.