Improvement: Mesh handle tutorials #2348
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| /* | ||
| This file is part of t8code. | ||
| t8code is a C library to manage a collection (a forest) of multiple | ||
| connected adaptive space-trees of general element types in parallel. | ||
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| Copyright (C) 2026 the developers | ||
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| t8code is free software; you can redistribute it and/or modify | ||
| it under the terms of the GNU General Public License as published by | ||
| the Free Software Foundation; either version 2 of the License, or | ||
| (at your option) any later version. | ||
|
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| t8code is distributed in the hope that it will be useful, | ||
| but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| GNU General Public License for more details. | ||
|
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| You should have received a copy of the GNU General Public License | ||
| along with t8code; if not, write to the Free Software Foundation, Inc., | ||
| 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. | ||
| */ | ||
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| /** \file t8_mesh_step3_adapt_forest.cxx | ||
| * This is the same as general/t8_step3_adapt_forest.cxx but using the mesh handle interface instead of the forest | ||
| * interface. | ||
| */ | ||
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| #include <t8.h> | ||
| #include <mesh_handle/mesh.hxx> | ||
| #include <mesh_handle/competence_pack.hxx> | ||
| #include <mesh_handle/constructor_wrappers.hxx> | ||
| #include <mesh_handle/mesh_io.hxx> | ||
| #include <mesh_handle/concepts.hxx> | ||
| #include <t8_types/t8_vec.hxx> | ||
| #include <memory> | ||
| #include <span> | ||
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| /* The data that determines the adaptation characteristics of our algorithm. | ||
| * In this example we want to adapt in a spherical shape around a given point. */ | ||
| struct adapt_data | ||
| { | ||
| std::array<double, 3> midpoint; /**< midpoint of our sphere. */ | ||
|
Collaborator
There was a problem hiding this comment. I prefer t8_3D_vec here (which is essentially the same but clearer) |
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| double refine_radius; /**< We refine inside this radius of our sphere.*/ | ||
| double coarsen_radius; /**< We coarsen outside this radius of our sphere. */ | ||
| }; | ||
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| /** The adaption callback function. This will refine elements inside of a given sphere and coarsen the elements | ||
| * outside of a given sphere. | ||
| * \tparam TMeshClass The mesh handle class. | ||
| * \param [in] mesh The mesh that should be adapted. | ||
| * \param [in] elements One element or a family of elements to consider for adaptation. | ||
| * \param [in] adapt_data The user data to be used during the adaptation process. | ||
| * \returns 1 if the first entry in \a elements should be refined, | ||
| * -1 if the family of elements should be coarsened, | ||
| * 0 else. | ||
| */ | ||
| template <t8_mesh_handle::T8MeshType TMeshClass> | ||
| int | ||
| adapt_callback ([[maybe_unused]] const TMeshClass &mesh, std::span<const typename TMeshClass::element_class> elements, | ||
| const adapt_data &adapt_data) | ||
| { | ||
| auto element_centroid = elements[0].get_centroid (); | ||
| double dist = t8_dist<t8_3D_vec, t8_3D_vec> (element_centroid, adapt_data.midpoint); | ||
| if (dist < adapt_data.refine_radius) { | ||
| return 1; // refine | ||
| } //first check if there is a family, and only if yes check if we should coarsen. | ||
|
Vyp3er marked this conversation as resolved.
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| else if ((elements.size () > 1) && (dist > adapt_data.coarsen_radius)) { | ||
| return -1; // coarsen | ||
| } | ||
| return 0; // do nothing | ||
| } | ||
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| /** Build our adapted mesh by transferring the adaption parameters and adapting once with our adapt_callback function. | ||
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Vyp3er marked this conversation as resolved.
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| * \tparam TMeshClass The mesh handle class. | ||
| * \param sc_MPI_Comm The MPI Communicator. | ||
| * \param level The initial uniform refinement level. | ||
| * \returns Unique pointer to the adapted mesh. | ||
| */ | ||
| template <t8_mesh_handle::T8MeshType TMeshClass> | ||
| std::unique_ptr<TMeshClass> | ||
| build_mesh (sc_MPI_Comm comm, int level) | ||
| { | ||
| /*Generate a hybrid hypercube, made out of cubes, prisms etc. */ | ||
| auto mesh = t8_mesh_handle::handle_hypercube_hybrid_uniform_default<TMeshClass> (level, comm); | ||
| /*Defining the adaption parameters. */ | ||
| struct adapt_data adapt_params = { { 0.5, 0.5, 1.0 }, 0.2, 0.4 }; | ||
| mesh->set_balance (); | ||
| mesh->set_partition (); | ||
| /*Adapting once with our adapt_callback function. */ | ||
| mesh->set_adapt ( | ||
| TMeshClass::template mesh_adapt_callback_wrapper<adapt_data> (adapt_callback<TMeshClass>, adapt_params)); | ||
| mesh->set_ghost (); | ||
| mesh->commit (); | ||
| return mesh; | ||
| } | ||
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| /** Entry point of the program. */ | ||
| int | ||
| main (int argc, char **argv) | ||
| { | ||
| /*Initialize MPI. This has to happen before we initialize sc or t8code. */ | ||
| int mpiret = sc_MPI_Init (&argc, &argv); | ||
| /*Error check the MPI return value. */ | ||
| SC_CHECK_MPI (mpiret); | ||
| /* Initialize the sc library, has to happen before we initialize t8code. */ | ||
| sc_init (sc_MPI_COMM_WORLD, 1, 1, NULL, SC_LP_ESSENTIAL); | ||
| /* Initialize t8code with log level SC_LP_PRODUCTION. See sc.h for more info on the log levels. */ | ||
| t8_init (SC_LP_PRODUCTION); | ||
| /* We will use MPI_COMM_WORLD as a communicator. */ | ||
| sc_MPI_Comm comm = sc_MPI_COMM_WORLD; | ||
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| /* Print a starting message. */ | ||
| t8_global_productionf (" [tutorial] \n"); | ||
|
Collaborator
There was a problem hiding this comment. We should also think of something different than "tutorial" here. Any ideas? |
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| t8_global_productionf (" [tutorial] Hello, this is the mesh adaptation example of t8code using the mesh handle.\n"); | ||
| t8_global_productionf (" [tutorial] In this example we will adapt a mesh in a spherical shape around a given point " | ||
| "and write the adapted mesh to a vtu file.\n"); | ||
| t8_global_productionf (" [tutorial] \n"); | ||
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| using mesh_type = t8_mesh_handle::mesh<>; | ||
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| t8_global_productionf (" [tutorial] \n"); | ||
| t8_global_productionf (" [tutorial] Creating an adapted mesh.\n"); | ||
| t8_global_productionf (" [tutorial] \n"); | ||
| /* The initial uniform refinement level. */ | ||
| int uniform_level = 3; | ||
| /* Building the Mesh*/ | ||
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Vyp3er marked this conversation as resolved.
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| auto mesh = build_mesh<mesh_type> (comm, uniform_level); | ||
| /* Write the mesh to a vtu file. */ | ||
| t8_global_productionf (" [tutorial] \n"); | ||
| t8_global_productionf (" [tutorial] Writing adapted mesh to vtu file: adapted_mesh.vtu\n"); | ||
| t8_global_productionf (" [tutorial] \n"); | ||
| t8_mesh_handle::write_mesh_to_vtk (*mesh, "adapted_mesh.vtu"); | ||
|
Collaborator
There was a problem hiding this comment. We should also add a step here such that the files are not overridden by the next step. Maybe we can do step_mh3 or smth like this? (for mesh handle). Maybe you have a better idea, i am not fully convinced of my idea. |
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| sc_finalize (); | ||
| mpiret = sc_MPI_Finalize (); | ||
| SC_CHECK_MPI (mpiret); | ||
| return 0; | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,138 @@ | ||
| /* | ||
| This file is part of t8code. | ||
| t8code is a C library to manage a collection (a forest) of multiple | ||
| connected adaptive space-trees of general element types in parallel. | ||
|
|
||
| Copyright (C) 2026 the developers | ||
|
|
||
| t8code is free software; you can redistribute it and/or modify | ||
| it under the terms of the GNU General Public License as published by | ||
| the Free Software Foundation; either version 2 of the License, or | ||
| (at your option) any later version. | ||
|
|
||
| t8code is distributed in the hope that it will be useful, | ||
| but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| GNU General Public License for more details. | ||
|
|
||
| You should have received a copy of the GNU General Public License | ||
| along with t8code; if not, write to the Free Software Foundation, Inc., | ||
| 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. | ||
| */ | ||
|
|
||
| /** \file t8_mesh_step3_adapt_mesh.cxx | ||
| * This is the same as general/t8_step3_adapt_forest.cxx but using the mesh handle interface instead of the forest | ||
| * interface. | ||
| */ | ||
|
|
||
| #include <t8.h> | ||
| #include <mesh_handle/mesh.hxx> | ||
| #include <mesh_handle/competence_pack.hxx> | ||
| #include <mesh_handle/constructor_wrappers.hxx> | ||
| #include <mesh_handle/mesh_io.hxx> | ||
| #include <mesh_handle/concepts.hxx> | ||
| #include <t8_types/t8_vec.hxx> | ||
| #include <memory> | ||
| #include <span> | ||
|
|
||
| /* The data that determines the adaptation characteristics of our algorithm. | ||
| * In this example we want to adapt in a spherical shape around a given point. */ | ||
| struct adapt_data | ||
| { | ||
| t8_3D_vec midpoint; /**< midpoint of our sphere. */ | ||
| double refine_radius; /**< We refine inside this radius of our sphere.*/ | ||
| double coarsen_radius; /**< We coarsen outside this radius of our sphere. */ | ||
| }; | ||
|
|
||
| /** The adaption callback function. This will refine elements inside of a given sphere and coarsen the elements | ||
| * outside of a given sphere. | ||
| * \tparam TMeshClass The mesh handle class. | ||
| * \param [in] mesh The mesh that should be adapted. | ||
| * \param [in] elements One element or a family of elements to consider for adaptation. | ||
| * \param [in] adapt_data The user data to be used during the adaptation process. | ||
| * \returns 1 if the first entry in \a elements should be refined, | ||
| * -1 if the family of elements should be coarsened, | ||
| * 0 else. | ||
| */ | ||
| template <t8_mesh_handle::T8MeshType TMeshClass> | ||
| int | ||
| adapt_callback ([[maybe_unused]] const TMeshClass &mesh, std::span<const typename TMeshClass::element_class> elements, | ||
| const adapt_data &adapt_data) | ||
| { | ||
| auto element_centroid = elements[0].get_centroid (); | ||
| double dist = t8_dist<t8_3D_vec, t8_3D_vec> (element_centroid, adapt_data.midpoint); | ||
| if (dist < adapt_data.refine_radius) { | ||
| return 1; /**< Refine. */ | ||
| } /** First check if there is a family, and only if yes coarsen. */ | ||
| else if ((elements.size () > 1) && (dist > adapt_data.coarsen_radius)) { | ||
| return -1; /**< Coarsen. */ | ||
| } | ||
| return 0; /**< Do Nothing. */ | ||
| } | ||
|
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| /** Build our adapted mesh by transferring the adaption parameters and adapting once with our \ref adapt_callback function. | ||
| * \tparam TMeshClass The mesh handle class. | ||
| * \param sc_MPI_Comm The MPI Communicator. | ||
| * \param level The initial uniform refinement level. | ||
| * \returns Unique pointer to the adapted mesh. | ||
| */ | ||
| template <t8_mesh_handle::T8MeshType TMeshClass> | ||
| std::unique_ptr<TMeshClass> | ||
| build_mesh (sc_MPI_Comm comm, int level) | ||
| { | ||
| /*Generate a hybrid hypercube, made out of cubes, prisms etc. */ | ||
| auto mesh = t8_mesh_handle::handle_hypercube_hybrid_uniform_default<TMeshClass> (level, comm); | ||
| /*Defining the adaption parameters. */ | ||
| struct adapt_data adapt_params = { { 0.5, 0.5, 1.0 }, 0.2, 0.4 }; | ||
| mesh->set_balance (); | ||
| mesh->set_partition (); | ||
| /*Adapting once with our adapt_callback function. */ | ||
| mesh->set_adapt ( | ||
| TMeshClass::template mesh_adapt_callback_wrapper<adapt_data> (adapt_callback<TMeshClass>, adapt_params)); | ||
| mesh->set_ghost (); | ||
| mesh->commit (); | ||
| return mesh; | ||
| } | ||
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| /** Entry point of the program. */ | ||
| int | ||
| main (int argc, char **argv) | ||
| { | ||
| /*Initialize MPI. This has to happen before we initialize sc or t8code. */ | ||
| int mpiret = sc_MPI_Init (&argc, &argv); | ||
| /*Error check the MPI return value. */ | ||
| SC_CHECK_MPI (mpiret); | ||
| /* Initialize the sc library, has to happen before we initialize t8code. */ | ||
| sc_init (sc_MPI_COMM_WORLD, 1, 1, NULL, SC_LP_ESSENTIAL); | ||
| /* Initialize t8code with log level SC_LP_PRODUCTION. See sc.h for more info on the log levels. */ | ||
| t8_init (SC_LP_PRODUCTION); | ||
| /* We will use MPI_COMM_WORLD as a communicator. */ | ||
| sc_MPI_Comm comm = sc_MPI_COMM_WORLD; | ||
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| /* Print a starting message. */ | ||
| t8_global_productionf (" [tutorial] \n"); | ||
| t8_global_productionf (" [tutorial] Hello, this is the mesh adaptation example of t8code using the mesh handle.\n"); | ||
| t8_global_productionf (" [tutorial] In this example we will adapt a mesh in a spherical shape around a given point " | ||
| "and write the adapted mesh to a vtu file.\n"); | ||
| t8_global_productionf (" [tutorial] \n"); | ||
|
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| using mesh_type = t8_mesh_handle::mesh<>; | ||
|
|
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| t8_global_productionf (" [tutorial] \n"); | ||
| t8_global_productionf (" [tutorial] Creating an adapted mesh.\n"); | ||
| t8_global_productionf (" [tutorial] \n"); | ||
| /* The initial uniform refinement level. */ | ||
| int uniform_level = 3; | ||
| /* Building the mesh. */ | ||
| auto mesh = build_mesh<mesh_type> (comm, uniform_level); | ||
| /* Write the mesh to a vtu file. */ | ||
| t8_global_productionf (" [tutorial] \n"); | ||
| t8_global_productionf (" [tutorial] Writing adapted mesh to vtu file: step3_adapted_mesh.vtu\n"); | ||
| t8_global_productionf (" [tutorial] \n"); | ||
| t8_mesh_handle::write_mesh_to_vtk (*mesh, "step3_adapted_mesh.vtu"); | ||
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| sc_finalize (); | ||
| mpiret = sc_MPI_Finalize (); | ||
| SC_CHECK_MPI (mpiret); | ||
| return 0; | ||
| } |
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We should rename this as we try to hide the "forest". Do you have an idea? Also maybe we should write a Readme such that it is clear why this is "step3" although we have no step 1 and 2 in this folder. I removed the "step5" for the other mesh handle tutorial but maybe its good to keep the name but state it clearly in the readme (and link to steps 0-2 there as they are necessary to understand also for the mesh handle)