chore(tidy3d-client): bring back robust VTU planar axis detection fix (#3914)

Compute-RevId: 080b8c67e3bffd07374446037be265a627513fa3
Flex-RevId: dfe7bacef8c35d532e0169decbd7eba760ca6aa9

Author: momchil-flex

docs/_ext/custom-robots.py

@@ -4,12 +4,8 @@
 
 
 def process_robots_txt(app, exception):
-    if exception:
-        return
     # Get the path to the robots.txt file
     robots_file = os.path.join(app.outdir, "robots.txt")
-    if not os.path.isfile(robots_file):
-        return
     with open(robots_file) as f:
         contents = f.read()
 

docs/_templates/module.rst

@@ -50,3 +50,9 @@
    {% endif %}
    {% endif %}
    {% endblock %}
+
+
+   .. rubric:: Inherited Common Usage
+
+   .. include:: ../_custom_autosummary/{{ fullname }}.rst
+      :optional:

tests/test_data/test_datasets.py

@@ -1190,6 +1190,105 @@ def test_from_vtk():
         _ = td.TriangularGridDataset.from_vtk("tests/data/gmsh_2d.vtk")
 
 
+def test_triangular_from_vtu_near_planar_large_coordinates(tmp_path):
+    """Regression for large-coordinate planar slices with small normal-axis jitter."""
+    pytest.importorskip("vtk")
+    import vtk
+
+    import tidy3d as td
+
+    tri_grid = td.TriangularGridDataset(
+        normal_axis=1,
+        normal_pos=0.0,
+        points=td.PointDataArray(
+            [
+                [100000.0, 0.0],
+                [101000.0, 0.0],
+                [100000.0, 690.0],
+                [101000.0, 690.0],
+            ],
+            dims=("index", "axis"),
+        ),
+        cells=td.CellDataArray([[0, 1, 2], [1, 2, 3]], dims=("cell_index", "vertex_index")),
+        values=td.IndexedDataArray(
+            [1.0, 2.0, 3.0, 4.0], coords={"index": np.arange(4)}, name="temp"
+        ),
+    )
+
+    vtu_path = tmp_path / "near_planar_large_coords.vtu"
+    tri_grid.to_vtu(vtu_path)
+
+    # Inject tiny jitter in the nominally planar normal direction.
+    reader = vtk.vtkXMLUnstructuredGridReader()
+    reader.SetFileName(str(vtu_path))
+    reader.Update()
+    grid = reader.GetOutput()
+    points = grid.GetPoints()
+    for ind in range(points.GetNumberOfPoints()):
+        x, _, z = points.GetPoint(ind)
+        points.SetPoint(ind, x, 6e-6 if (ind % 2) == 0 else -6e-6, z)
+    points.Modified()
+
+    writer = vtk.vtkXMLUnstructuredGridWriter()
+    writer.SetFileName(str(vtu_path))
+    writer.SetInputData(grid)
+    writer.Write()
+
+    loaded = td.TriangularGridDataset.from_vtu(vtu_path, field="temp")
+    assert loaded.normal_axis == 1
+    assert abs(float(loaded.normal_pos)) < 1e-4
+    assert loaded.points.sizes["index"] == 4
+
+
+def test_triangular_from_vtu_far_from_origin_small_extent(tmp_path):
+    """Regression: tolerance must depend on extent, not absolute position."""
+    pytest.importorskip("vtk")
+    import vtk
+
+    import tidy3d as td
+
+    tri_grid = td.TriangularGridDataset(
+        normal_axis=1,
+        normal_pos=0.0,
+        points=td.PointDataArray(
+            [
+                [1e9, -2e9],
+                [1e9 + 2.0, -2e9],
+                [1e9, -2e9 + 1.0],
+                [1e9 + 2.0, -2e9 + 1.0],
+            ],
+            dims=("index", "axis"),
+        ),
+        cells=td.CellDataArray([[0, 1, 2], [1, 2, 3]], dims=("cell_index", "vertex_index")),
+        values=td.IndexedDataArray(
+            [1.0, 2.0, 3.0, 4.0], coords={"index": np.arange(4)}, name="temp"
+        ),
+    )
+
+    vtu_path = tmp_path / "far_origin_small_extent.vtu"
+    tri_grid.to_vtu(vtu_path)
+
+    reader = vtk.vtkXMLUnstructuredGridReader()
+    reader.SetFileName(str(vtu_path))
+    reader.Update()
+    grid = reader.GetOutput()
+    points = grid.GetPoints()
+    for ind in range(points.GetNumberOfPoints()):
+        x, _, z = points.GetPoint(ind)
+        points.SetPoint(ind, x, 2e-7 if (ind % 2) == 0 else -2e-7, z)
+    points.Modified()
+
+    writer = vtk.vtkXMLUnstructuredGridWriter()
+    writer.SetFileName(str(vtu_path))
+    writer.SetInputData(grid)
+    writer.Write()
+
+    loaded = td.TriangularGridDataset.from_vtu(vtu_path, field="temp")
+    assert loaded.normal_axis == 1
+    assert abs(float(loaded.normal_pos)) < 1e-5
+    assert loaded.points.sizes["index"] == 4
+
+
 def test_tetrahedral_from_vtk_obj_without_cell_types_array():
     """Regression test for VTK objects with missing ``GetCellTypesArray`` output."""
     pytest.importorskip("vtk")

tidy3d/components/data/unstructured/triangular.py

@@ -175,7 +175,12 @@ def _from_vtk_obj(
 
         # detect zero size dimension
         bounds = np.max(points_numpy, axis=0) - np.min(points_numpy, axis=0)
-        zero_dims = np.where(np.isclose(bounds, 0, atol=1e-6))[0]
+        # VTU slices can accumulate small floating-point jitter in the nominally
+        # zero-thickness direction. Scale tolerance with geometry extent (rather than
+        # absolute coordinate value) to avoid origin-dependent behavior.
+        size_scale = float(np.max(bounds)) if bounds.size > 0 else 0.0
+        zero_dim_tol = max(1e-6, 2e-8 * size_scale)
+        zero_dims = np.where(np.isclose(bounds, 0, atol=zero_dim_tol))[0]
 
         if len(zero_dims) != 1:
             raise DataError(