Revert "Update the iso_contours example using iso_surfaces operator (#1164)" (#1203)

This reverts commit a900a05.

Author: MichaelNale

examples/12-fluids/03-fluids_isosurface.py

@@ -64,9 +64,13 @@
 ###############################################################################
 # Evaluate iso-surfaces
 # ~~~~~~~~~~~~~~
-# We can finally use the iso_surfaces operator on this specific variable.
-# We choose to cut the whole mesh with 9 iso-surface manually selected between
-# the min and max of the static_pressure variable.
+# We can finally use the mesh_cut operator on this specific variable.
+# We choose to cut the whole with 5 iso-surface equally spaced between min and max.
+
+max_pressure = 361.8170  # Pa
+min_pressure = -153.5356  # Pa
+number_of_iso_surface = 5
+step = (max_pressure - min_pressure) / number_of_iso_surface
 
 pl = DpfPlotter()
 c_pos_iso = [
@@ -83,20 +87,18 @@
     opacity=0.3,
 )
 
-vec_iso_values = [-153.6, -100.0, -50.0, 50.0, 100.0, 150.0, 200.0, 300.0, 361.8]
-
-iso_surfaces_op = dpf.operators.mesh.iso_surfaces(field=P_S[0], mesh=whole_mesh, slice_surfaces=True,
-                                              vector_iso_values=vec_iso_values)
-
-iso_surfaces_meshes = iso_surfaces_op.outputs.meshes()
-
-iso_surfaces_fields = iso_surfaces_op.outputs.fields_container()
-
-for i in range(len(iso_surfaces_fields)):
+for i in range(number_of_iso_surface):
+    iso_surface = dpf.operators.mesh.mesh_cut(
+        field=P_S[0], iso_value=min_pressure, closed_surface=0, mesh=whole_mesh, slice_surfaces=True
+    ).eval()
+    P_S_step = dpf.Field(location=dpf.locations.overall, nature=dpf.common.natures.scalar)
+    P_S_step.append([min_pressure], i)
+    P_S_step.name = "static pressure"
+    P_S_step.unit = "Pa"
     pl.add_field(
-        field=iso_surfaces_fields[i], meshed_region=iso_surfaces_meshes[i], style="surface", show_edges=False,
-        show_axes=True
+        field=P_S_step, meshed_region=iso_surface, style="surface", show_edges=False, show_axes=True
     )
+    min_pressure += step
 
 pl.show_figure(show_axes=True, cpos=c_pos_iso)