Function fan_cell

pub fn fan_cell<T: CoordsFloat>(
    cmap: &mut CMap2<T>,
    face_id: FaceIdType,
    new_darts: &[DartIdType],
) -> Result<(), TriangulateError>

Triangulates a face using a fan triangulation method.

This function triangulates a cell (face) in a 2D combinatorial map by creating a fan of triangles from a chosen vertex to all other vertices of the polygon, if such a vertex exist.

Note that this function will not have any effect if the polygon isn’t fannable.

Arguments

• cmap: &mut CMap2 - A mutable reference to the modified CMap2.
• face_id: FaceIdentifier - Identifier of the face to triangulate within the map.
• new_darts: &[DartIdentifier] - Identifiers of pre-allocated darts for the new edges; the slice length should match the expected number of edges created by the triangulation. For an n-sided polygon, the number of created edge is n-3, so the number of dart is (n-3)*2.

Behavior

• The function begins by checking if the face has 3 or fewer vertices, in which case it’s already triangulated or cannot be further processed.
• It verifies if the number of new darts matches the expected number for triangulation.
• The function then attempts to find a vertex from which all other vertices can be seen (a star vertex), using the orientation properties of N-maps.
• If such a star vertex is found, the function proceeds to create triangles by linking new darts in a fan-like structure from this vertex. Otherwise, the cell is left unchanged

Errors

This function will return an error if the face wasn’t triangulated. There can be multiple reason for this:

• The face is incompatible with the operation (made of 1, 2 or 3 vertices)
• The number of pre-allocated darts did not match the expected number (see [#arguments])
• The face contains one or more undefined vertices
• The face isn’t starrable

Note that in any of these cases, the face will remain the same as it was before the function call.