pub fn silhouettes(
model: &Model,
shape: &Shape,
direction: Vector,
tol: Tolerances,
) -> OgeomResult<Vec<Silhouette>>Expand description
The exact silhouettes of a shape, seen along direction.
A silhouette is the locus where the surface normal is perpendicular to the view: for a sphere the great circle whose plane the direction is normal to, for a cylinder the two rulings furthest to either side, for a cone the two rulings through its apex where the same holds. Planes have none (a plane either faces the eye or does not), and a face whose surface has no closed-form silhouette is refused by name.
Each curve comes back trimmed to the stretch that lies within its own face, decided by sampling the face’s trim, so a silhouette on a face that was cut away is absent rather than drawn through thin air.
§Errors
OgeomError::Construction if the
direction has no length, or a face carries a surface whose silhouette has
no closed form.