Function signed_distances 

pub fn signed_distances(
    mesh_b: &Mesh,
    bvh_b: &Bvh,
    sign: &SignData,
    points_in_b: &[[f32; 3]],
    max_distance: f32,
    out: &mut [f32],
) -> Result<()>

Signed distances from points_in_b (in mesh B’s local coordinates) to mesh B: out[i] gets the value for points_in_b[i].

• The magnitude is the distance to the closest point of B, from fast_mesh_query::closest_point.
• The sign comes from sign (see SignData): negative behind the surface (inside), positive in front of it (outside). A point exactly on the surface gets +0.0; a point whose side is undecided (exactly in the tangent plane of its closest feature) counts as outside.
• A point farther than max_distance from the surface (inclusive bound) gets f32::INFINITY, meaning far, with no sign. That includes points deeper inside than max_distance. An infinite max_distance computes every point.

Nothing is allocated per point. With the parallel feature, large batches run in chunks on rayon’s pool, each chunk into its own buffer; the values are the same, bit for bit.

Errors

Everything is checked before anything is written, so on error out is unchanged:

• FieldsError::InvalidInput when the slices differ in length, a point is not finite (NaN or infinite), or max_distance is negative or NaN;
• FieldsError::Query with MeshMismatch or StaleBvh when bvh_b does not match the current mesh_b;
• FieldsError::InvalidInput when sign is not current for mesh_b and bvh_b (see SignData::is_current).