Bugfix: Curved geometries #2073

sandro-elsweijer · 2026-01-09T09:16:01Z

Closes #2074

Describe your changes here:
I am so sorry for the diff count. But a huge part of this PR is documentation.
Fixes a bug in our curved mesh algorithms in which in some edge cases geometries were either not linked to tree faces or they were linked with wrong parameters. This can be observed by executing the curved mesh tutorial for tetrahedra on main and on this branch.

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codecov · 2026-01-13T14:56:27Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.05%. Comparing base (2625544) to head (1bac59c).
⚠️ Report is 35 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2073   +/-   ##
=======================================
  Coverage   77.05%   77.05%           
=======================================
  Files         112      112           
  Lines       18959    18959           
=======================================
  Hits        14608    14608           
  Misses       4351     4351

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lenaploetzke

First part of review

src/t8.h

src/t8_cad/t8_cad.cxx

lenaploetzke · 2026-01-15T11:06:59Z

src/t8_cad/t8_cad.cxx

+    }
+  }
+
+  /* Lastly, we put the parameters into our output array. */


Ok i think overall this function works.

lenaploetzke · 2026-01-15T11:16:38Z

src/t8_cad/t8_cad.cxx

+    /* Convert reference parameters to OCCT point */
+    gp_Pnt2d reference_point (reference_face_params.value ()[0], reference_face_params.value ()[1]);
+
+    /* If the edge is a seam we have to get both points and check which one is closer.


points? parameters maybe?

lenaploetzke · 2026-01-15T11:17:28Z

src/t8_cad/t8_cad.cxx

+       We iterate over all edges of the face and check if the edges are the same as the
+       input edge. Then we check if the converted parameters are closer to the
+       already computed parameters. */
+    bool first_point = true;


lenaploetzke · 2026-01-15T11:18:45Z

src/t8_cad/t8_cad.cxx

+      if (edge.IsSame (current_edge)) {
+        Handle_Geom2d_Curve curve_on_surface = BRep_Tool::CurveOnSurface (edge, face, first, last);
+        /* If it is the first seam we compute the parameters. */
+        if (first_point) {


you can also again solve this with uv as optional can't you?

lenaploetzke · 2026-01-15T11:51:31Z

src/t8_cmesh/t8_cmesh_io/t8_cmesh_readmshfile.cxx

    }
    /* Now we can check if every node lies on the surface and retrieve its parameters */
    if (surface_index) {
      int all_nodes_on_surface = 1;


Can we use maybe a bool? 😅

Typos Co-authored-by: lenaploetzke <70579874+lenaploetzke@users.noreply.github.com>

lenaploetzke

Please also merge main

lenaploetzke · 2026-01-16T09:10:19Z

src/t8_cmesh/t8_cmesh_io/t8_cmesh_readmshfile.cxx

+#include <ranges>
+#include <type_traits>


Can you check if you need these two includes?

lenaploetzke · 2026-01-16T09:30:15Z

src/t8_cmesh/t8_cmesh_io/t8_cmesh_readmshfile.cxx

      if (dim == 2) {
-        face_nodes[i_face_node] = tree_nodes[i_face_node];
+        face_nodes.push_back (tree_nodes[i_face_node]);
+        T8_ASSERT (num_faces == 1);


Is this necessary? Only chance that num_faces is set is here

switch (dim) { case 0: num_faces = 0; break; case 1: num_faces = 0; break; case 2: num_faces = 1; break; case 3: num_faces = t8_eclass_num_faces[eclass]; break; default: SC_ABORTF ("Invalid dimension of tree. Dimension: %i\n", dim); }

lenaploetzke · 2026-01-16T09:52:15Z

src/t8_cmesh/t8_cmesh_io/t8_cmesh_readmshfile.cxx

+      for (auto &face_node : face_nodes) {
+        switch (face_node.entity_dim) {
+        case 2:
+          /* Nothing to do. */


Dont have to convert because the face node is directly on surface right?

lenaploetzke · 2026-01-16T10:15:19Z

src/t8_cmesh/t8_cmesh_io/t8_cmesh_readmshfile.cxx

+     * If the edge is locked for edges on surfaces we have to skip this edge */
    else if (edge_geometry_dim == 2 && edge_geometries[i_tree_edges + num_edges] >= 0) {
+
+      /* We also skip this exge if the edge is on a plane. Planes have no curvature and


Suggested change

/* We also skip this exge if the edge is on a plane. Planes have no curvature and

/* We also skip this edge if the edge is on a plane. Planes have no curvature and

sandro-elsweijer added 4 commits December 8, 2025 13:00

add a convenience function for floating point equality

32736c4

major bugfix and restructuring needed to find the bug

d00d9b1

add debug check

83e95dc

documentation

94456c4

sandro-elsweijer self-assigned this Jan 9, 2026

sandro-elsweijer changed the title ~~Bugfic: Curved geometries~~ Bugfix: Curved geometries Jan 12, 2026

sandro-elsweijer removed their assignment Jan 13, 2026

sandro-elsweijer marked this pull request as ready for review January 13, 2026 14:39

Merge branch 'main' into fix-curved_geometries

eb77d50

sandro-elsweijer added 2 commits January 13, 2026 16:17

fix documentation

634ef37

fix documentation

1bac59c

lenaploetzke reviewed Jan 15, 2026

View reviewed changes

sandro-elsweijer and others added 4 commits January 15, 2026 14:43

remove unused function

cd00821

add assertions

02d743c

Apply suggestions from code review

acd1961

Typos Co-authored-by: lenaploetzke <70579874+lenaploetzke@users.noreply.github.com>

use optional.has_value() for better readability

39d087a

lenaploetzke reviewed Jan 16, 2026

View reviewed changes

	/* We also skip this exge if the edge is on a plane. Planes have no curvature and
	/* We also skip this edge if the edge is on a plane. Planes have no curvature and

		#include <ranges>
		#include <type_traits>

Bugfix: Curved geometries #2073

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Bugfix: Curved geometries #2073

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sandro-elsweijer commented Jan 9, 2026 •

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