message: Add facet_edge_vertex method
diff: @@ -453,10 +453,8 @@ namespace RINGMesh {
  */
  double facet_edge_length( index_t facet_id, index_t vertex_id ) const
  {
  - const vec3& e0 = vertex( facet_vertex( facet_id, vertex_id ) ) ;
  - const vec3& e1 = vertex(
  - facet_vertex( facet_id,
  - next_facet_vertex( facet_id, vertex_id ) ) ) ;
  + const vec3& e0 = vertex( facet_edge_vertex( facet_id, vertex_id, 0 ) ) ;
  + const vec3& e1 = vertex( facet_edge_vertex( facet_id, vertex_id, 1 ) ) ;
  return ( e1 - e0 ).length() ;
  }
  /*!
  @@ -466,12 +464,29 @@ namespace RINGMesh {
  */
  vec3 facet_edge_barycenter( index_t facet_id, index_t vertex_id ) const
  {
  - const vec3& e0 = vertex( facet_vertex( facet_id, vertex_id ) ) ;
  - const vec3& e1 = vertex(
  - facet_vertex( facet_id,
  - next_facet_vertex( facet_id, vertex_id ) ) ) ;
  + const vec3& e0 = vertex( facet_edge_vertex( facet_id, vertex_id, 0 ) ) ;
  + const vec3& e1 = vertex( facet_edge_vertex( facet_id, vertex_id, 1 ) ) ;
  return ( e1 + e0 ) / 2. ;
  }
  + /*!
  + * @brief Gets the vertex index on the facet edge
  + * @param[in] facet_id index of the facet
  + * @param[in] edge_id index of the edge in the facet \param facet_id
  + * @param[in] vertex_id index of the local vertex in the edge \param edge_id (0 or 1)
  + * @return the vertex index
  + */
  + index_t facet_edge_vertex(
  + index_t facet_id,
  + index_t edge_id,
  + index_t vertex_id ) const
  + {
  + if( vertex_id == 0 ) {
  + return facet_vertex( facet_id, edge_id ) ;
  + } else {
  + return facet_vertex( facet_id,
  + ( edge_id + vertex_id ) % nb_facet_vertices( facet_id ) ) ;
  + }
  + }
  /*!
  * Computes the Mesh facet normal
  