CM2 MeshTools® SDK /release 5.6.0 Preview 1

• Major version. Due to changes in the API, client applications must be recompiled against the new headers.
• Lib names now end with _56 (Windows®), 5.6.0 with symlinks from 5.6 (Linux®, macOS®).
• Visual Studio 2015 deprecated (will be no longer provided in future versions).
• CM2 SurfMesh T3 and CM2 SurfMesh Q4 upgraded to OpenCascade 7.8.0, except the Visual Studio 2010 and 2015 builds which are still based on OpenCascade 7.6.0 (because VS 2010/2015 don’t support C++11 required by OCCT 7.8.0).

CM2 SurfMesh T3, CM2 SurfMesh Q4

• New data_type::vertex_H (resp. curve_H, surface_H) for user-defined mesh sizes (isotropic) on specific vertices (resp. curves, surfaces).
  The precedence order is:
  1. vertex_H (highest precedence).
  2. curve_H.
  3. surface_H.
  4. settings_type::target_h (lowest precedence).

  Note that the mesher may use reduced mesh sizes in all directions (when settings_type::chordal_control_type = 1 or 3) or in selected directions (when settings_type::chordal_control_type = 2 or 4) to honor the settings_type::max_chordal_error criterion.

CM2 HexaMesh Iso

• New settings_type::conformation_level (replacing settings_type::make_conformation_flag, see Breaking Changes below).
  The value for this setting can be:
  • 0 : Minimal conformation: nothing specific is done to force conformal joints in the mesh.
    Non-conformal joints (i.e. quad faces connected to two triangle faces) are possible everywhere in the mesh but many joints can be still be conformal (i.e. quad faces connected to quad faces, triangle faces connected to triangle faces).
    Equivalent to former settings_type::make_conformation_flag = false.
  • 1 : Partial conformation: conformal joints are enforced only near the hard quadrangles. Joints elsewhere inside the domain can still be non-conformal. This type of conformation is new in this release.
  • 2+: Full conformation: conformal joints are enforced everywhere in the mesh.
    Equivalent to former settings_type::make_conformation_flag = true.
• New settings_type::hard_quads_enforcement_flag to force the recovery of hard quadrangles (as much as possible).
  If the recovery of all boundary (or any hard embedded) quadrangles isn’t a requirement for you and the split into pairs of triangles is acceptable, you can turn off this flag to save nodes, elements and get a better mesh (usually).
  Conversely, this flag set (true) together with settings_type::conformation_level >= 1 forces the recovery of all boundary quadrangles.

Core MeshTools libs

• New meshtools::vizir_sols to output solutions (scalars, vectors, tensors, matrices) for VIZIR (the new name of MEDIT).
  Note that the meshtools::medit_output, meshtools::medit_vector and meshtools::medit_tensor are replaced with their equivalent vizir functions or deprecated (see Breaking Changes below).
• New meshtools2d::mesh_parallelepiped_Q4 and meshtools2d::mesh_parallelepiped_T3 to generate structured surface meshes on parallelepipeds with CM2_FACEQ4 or CM2_FACET3 elements.

All meshers (except specialized tools)

• Significant speed-ups when using settings_type::target_metric and settings_type::max_gradation, especially with the anisotropic mesh generators (CM2 TetraMesh Aniso can show speed-ups of 300% on large meshes).
• Improvements in the shape qualities after the refine step (especially CM2 TetraMesh Aniso).
  This has several nice outcomes:
  • The mesh sizes (isotropic and anisotropic) are better honored.
  • It makes the optimization step easier and faster.
  • The final mesh can be significantly better.
• New scheme in the optimizers to remove long edges.

CM2 QuadMesh Iso, CM2 QuadMesh Aniso, CM2 SurfMesh Q4, CM2 SurfRemesh Q4

• Fortified all-quad mode: fewer CM2_DEGENERATED_ELEMENT errors.
• Somewhat faster optimization step (up to 15%) in large meshes.

CM2 SurfMesh T3, CM2 SurfMesh Q4

• Improvements in the quality of meshes.
• Better generation along curves with high gradients of tangents (see below on meshtools1d::mesh_curve_param).

CM2 TetraMesh Iso, CM2 TetraMesh Aniso

• Fewer Steiner nodes (again).
• Somewhat improved quality of the generated meshes.

CM2 TetraMesh Aniso

• Speed-ups (about 20%) even when settings_type::target_metric and settings_type::max_gradation aren’t used.

CM2 HexaMesh Iso

• More structured meshes (all-hexes).
• More OMP-parallelization (average gain = 15% on a 8-SMT CPU).
• Speed-ups in single-thread (average gain = 5%).

Core MeshTools libs

• meshtools1d::mesh_curve_param: improvements in the size of edges when curves have higher gradients of tangents.

All meshers (except specialized tools)

• The settings_type::max_gradation wasn’t always properly honored (the actual gradations could be excessive).

CM2 SurfMesh T3, CM2 SurfMesh Q4

• The bug in meshtools1d::mesh_curve_param (see below) could caused non-optimal meshes.
• The bug in meshtools2d::mesh_surface_param (see below) could caused strange aligned refinements.
• Loop curves couldn’t be merged.

CM2 SurfMesh Q4

• In all-quad mode: failed meshing surfaces when their contour had degenerated curves (segments with the two vertices merged together).

CM2 Intersect T3

• Spurious splits on regular (non-intersecting) edges sometimes.

Core MeshTools libs

• meshtools1d::mesh_curve_param: bug in 3-d metric reduction.
• meshtools2d::mesh_surface_param: non-optimal background mesh generation.

CM2 TriaMesh Iso, CM2 TriaMesh Aniso, CM2 TetraMesh Iso, CM2 TetraMesh Aniso

• Setting 'bool no_clamped_edges_flag' replaced with 'unsigned no_edge_with_nodes_below'.
  With the former flag, users were able to forbid edges between any two hard nodes (any nodes of the boundaries or embedded hard nodes). The new setting allows for a greater freedom over the type of edges to forbid.
  Consider nodes ordered in the data_type::pos matrix such that the highest boundary node id (say Nb) is before (i.e. smaller) than any other embedded node ids. Then no_edge_with_nodes_below = Nb+1 forbids any edge between two boundary nodes but still allows edges between a boundary node and an embedded node or between two embedded nodes.
  Conversely, if nodes are ordered such that the last embedded node (say with id Ne) is before any boundary nodes, then no_edge_with_nodes_below = Ne+1 forbids any edge between two embedded nodes but still allows edges between a boundary node and an embedded node or between two boundary nodes.
  no_edge_with_nodes_below = 0 (the default) is equivalent to the former default setting no_clamped_edges_flag = false.
  no_edge_with_nodes_below = data.pos.cols() is equivalent to the former setting no_clamped_edges_flag = true.

CM2 SurfMesh T3, CM2 SurfMesh Q4

• Upgraded to OpenCascade 7.8.0, except the Visual Studio 2010 and 2015 builds which are still based on OpenCascade 7.6.0 (because OCCT 7.8.0 requires C++11 and VS 2010/2015 don’t support it).
• The output fields data_type::color, data_type::colorE, data_type::merged_vertices, data_type::merged_curves and data_type::failed now follow the CAD indexing scheme.
  As OOCT has a 1-base indexing scheme, all these fields are 1-shifted vs. the previous version.

CM2 SurfMesh T3, CM2 SurfMesh Q4 (source-code licenses only)

• New requested enum in the CAD interface cad_interface::INDEX_BASE to specify the indexing scheme (0 or 1).
• New requested function in the CAD interface 'int cad_interface::orientation (const edge_type& E);' to give the orientation (+1, -1 or 0) of an edge.
• New requested functions in the CAD interface 'bool is_Uclosed (const surface_type& S);' and 'bool is_Vclosed (const surface_type& S);'
  to help tell whether a surface is periodic or not, on top of 'bool is_periodic (const surface_type& S, double& U_period, double& V_period);'.
• New requested function in the CAD interface 'bool periodic_surfaces_supported();' to tell whether the kernel supports periodic surfaces or not.

CM2 HexaMesh Iso

• bool settings_type::make_conformation_flag is replaced with unsigned settings_type::conformation_level.
  The former make_conformation_flag = false is now equivalent to conformation_level = 0.
  The former make_conformation_flag = true is now equivalent to conformation_level = 2.
• The internal formula used to compute the shape-quality of an hexahedron has changed (now gives higher values for elongated elements).

Core MeshTools libs

• meshtools::shape_qualities, meshtools::min_quality: changed values for hexahedrons (the new values are usually higher).
• meshtools::medit_output, meshtools::medit_vector and meshtools::medit_tensor are replaced with their equivalent vizir functions (some are just deprecated for the moment).