Feature: Add interpolate data functionality to mesh handle by lenaploetzke · Pull Request #2382 · DLR-AMR/t8code

lenaploetzke · 2026-07-29T14:35:54Z

Closes #2383
This also Closes #2115 as we dont need this functionality for the feature (expected before) and also PR #2248 is not needed anymore.
I think we can also
Closes #1654
as this completes the core functionality.

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codecov · 2026-08-06T10:34:14Z

Codecov Report

❌ Patch coverage is 93.51852% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.44%. Comparing base (85c9c9d) to head (2e67660).

Files with missing lines	Patch %	Lines
mesh_handle/internal/interpolate.hxx	91.17%	3 Missing ⚠️
mesh_handle/element.hxx	89.47%	2 Missing ⚠️
mesh_handle/mesh.hxx	93.54%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2382      +/-   ##
==========================================
+ Coverage   82.36%   82.44%   +0.08%     
==========================================
  Files         125      126       +1     
  Lines       20708    20806      +98     
==========================================
+ Hits        17056    17154      +98     
  Misses       3652     3652

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spenke91

Well, that was a nice dive into modern C++ template magic! 🪄
Took some time to get it, but I think the code is quite well designed. Great work @lenaploetzke !

I only have a bunch of small remarks and questions. To avoid spamming, I mostly refrained from adding hyphen-related comments; instead I would suggest the following replacements

user defined -> user-defined
index based -> index-based
span based -> span-based
element data handling -> element-data handling

But enough of being picky! Great feature, thanks a lot! 🙂
``

spenke91 · 2026-09-01T09:29:04Z

+            t8_global_infof ("No interpolation context set.\n");
+          }
+        }
+        else {
+          t8_global_infof ("The element data was not interpolated during adaptation. Use set_element_data() to provide "
+                           "new data or use the mesh competence interpolate_element_data_mesh_competence.\n");


Should this even be errors?

Maybe a user prefers to set new element data via set_element_data instead of using the competence? But yes, if we use the competence and do not provide a callback, i will throw an error.

spenke91 · 2026-09-01T09:30:19Z

+  /** Function that checks if a competence for the interpolation of element data is given.
+   * \return true if mesh has the competence, false otherwise.
+   */
+  static constexpr bool
+  has_interpolate_data_competence ()
+  {
+    return requires (SelfType& mesh) { mesh.set_partition_called (); };
+  }
+


Is this really a clean way of checking it has the competence? Seems strange and weird to maintain to me 🤔

Yes i finally found a way better solution!

spenke91 · 2026-09-01T09:33:56Z

+  static std::unordered_map<t8_forest_t, std::unique_ptr<mesh_interpolate_context_base>>&
+  get_map ()
+  {
+    static std::unordered_map<t8_forest_t, std::unique_ptr<mesh_interpolate_context_base>> map;


The whole std::unorder_map construct seems a little over-engineered to me. Out of curiosity: Do we already know whether we might ever register more than one forest-context pair at a time? If not, maybe we could make this whole registry more lightweight. On the other hand, I also don't mind having it a little too generic and flexible...

Maybe we have two meshes at the same time in an example and because of the static, they use the same registry. I think for this, the unordered map is maybe necessary

Co-authored-by: spenke91 <thomas.spenke@dlr.de>

lenaploetzke added 20 commits March 27, 2026 15:30

functionality for new element data

b83ef5a

[run ci] doxygen

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add file

08434d3

first ideas

a50f0a4

gitignore remove

a0de5f8

ideas for interpolate

2c3585f

use gtest common

0377490

no errors, very first version of test

6211e6b

interpolate

9668d8d

working version

236175d

remove new element data

4533f7d

Merge branch 'new-handle-mesh-competences' into handle-interpolate-data

dd6cf43

status

4c0b66d

Merge branch 'main' into handle-interpolate-data

afd64d2

fix things from merge

56de23b

renaming

ca55272

documentation

058f919

Add user data option for interpolate callback

d5d7848

Add repartition of data

b2c576d

resolve doxygen errors

4415d6a

lenaploetzke marked this pull request as draft August 3, 2026 06:17

Adapted test to be valid for each process number

e56d6ef

lenaploetzke marked this pull request as ready for review August 6, 2026 10:17

resolve doxygen error

a7bdf99

spenke91 self-assigned this Aug 10, 2026

spenke91 self-requested a review August 10, 2026 13:31

spenke91 requested changes Sep 1, 2026

View reviewed changes

spenke91 assigned lenaploetzke and unassigned spenke91 Sep 1, 2026

lenaploetzke and others added 4 commits September 11, 2026 10:02

Apply suggestions from code review

bd86598

Co-authored-by: spenke91 <thomas.spenke@dlr.de>

review

f52bb1b

Merge branch 'main' into handle-interpolate-data

68f21fd

Use test adapt callbacks for forest and add global handle id getter

2e67660

lenaploetzke assigned spenke91 and unassigned lenaploetzke Sep 11, 2026

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Feature: Add interpolate data functionality to mesh handle - #2382

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lenaploetzke commented Jul 29, 2026 •

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