fixes bug if traced cylinders are inovled in intersections

tests/test_components/test_autograd.py

@@ -826,7 +826,7 @@ def objective(*params):
         sim_fields = sim_full_traced.strip_traced_fields()
 
         # note: there is one traced structure in SIM_FULL already with 6 fields + 1 = 7
-        assert len(sim_fields) == 7
+        assert len(sim_fields) == 10
 
         sim_traced = sim_full_static.insert_traced_fields(sim_fields)
 

tests/utils.py

@@ -401,6 +401,11 @@ def make_custom_data(lims, unstructured):
     size=(8.0, 8.0, 8.0),
     run_time=1e-12,
     structures=[
+        td.Structure(
+            geometry=td.Cylinder(length=1, center=(-1 * tracer, 0, 0), radius=tracer, axis=2),
+            medium=td.Medium(permittivity=1 + tracer, name="dieletric"),
+            name="traced_dieletric_cylinder",
+        ),
         td.Structure(
             geometry=td.Box(size=(1, tracer, tracer), center=(-1 * tracer, 0, 0)),
             medium=td.Medium(permittivity=1 + tracer, name="dieletric"),

tidy3d/components/geometry/primitives.py

@@ -486,13 +486,15 @@ def _intersections_normal(self, z: float):
             `Shapely's Documentation <https://shapely.readthedocs.io/en/stable/project.html>`_.
         """
 
+        static_self = self.to_static()
+
         # radius at z
-        radius_offset = self._radius_z(z)
+        radius_offset = static_self._radius_z(z)
 
         if radius_offset <= 0:
             return []
 
-        _, (x0, y0) = self.pop_axis(self.center, axis=self.axis)
+        _, (x0, y0) = self.pop_axis(static_self.center, axis=self.axis)
         return [shapely.Point(x0, y0).buffer(radius_offset, quad_segs=_N_SHAPELY_QUAD_SEGS)]
 
     def _intersections_side(self, position, axis):