Function classify_in_solid 

pub fn classify_in_solid(
    model: &Model,
    solid: &Shape,
    point: Point,
    deflection: Deflection,
    tol: Tolerances,
) -> OgeomResult<Containment>

Where a point sits relative to a closed shell or solid.

Ray casting against the tessellation: a ray from the point crosses the boundary an odd number of times if and only if it started inside.

Errors

As triangulate(), plus OgeomError::Construction if the boundary is not closed (an open shell has no inside), and OgeomError::NotDone if every ray tried hit an edge or a vertex, where the crossing count is ambiguous.