From 201b9851c1bb57095583410a5f428d4e6c311674 Mon Sep 17 00:00:00 2001
From: LyceanEM <60020395+LyceanEM@users.noreply.github.com>
Date: Mon, 4 Nov 2024 21:33:01 +0000
Subject: [PATCH] I have added an import function to take pyvista meshes and
 convert them to meshio ones for use within lyceanem.

---
 lyceanem/utility/mesh_functions.py | 44 ++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 lyceanem/utility/mesh_functions.py

diff --git a/lyceanem/utility/mesh_functions.py b/lyceanem/utility/mesh_functions.py
new file mode 100644
index 0000000..4ebceb9
--- /dev/null
+++ b/lyceanem/utility/mesh_functions.py
@@ -0,0 +1,44 @@
+import pyvista as pv
+import meshio
+
+def pyvista_to_meshio(polydata_object):
+    """
+    Convert a pyvista object to a meshio object
+    """
+    #extract only the triangles
+    if type(polydata_object )==pv.core.pointset.UnstructuredGrid:
+        cells =id_cells(polydata_object.cells)
+    else:
+        cells =id_cells(polydata_object.faces)
+    meshio_object = meshio.Mesh(
+        points=polydata_object.points,
+        cells=cells,
+        point_data=polydata_object.point_data,
+    )
+    return meshio_object
+
+def id_cells(faces):
+    import numpy as np
+    cell_types ={1 :"vertex",
+                2 :"line",
+                3 :"triangle",
+                4 :"quad"
+                }
+    cells ={"vertex" :[],
+           "line" :[],
+           "triangle" :[],
+           "quad" :[]
+           }
+
+    while (faces.shape[0 ]>=1):
+        trim_num =faces[0]
+        temp_array =faces[1:trim_num +1]
+        cells[cell_types[trim_num]].append(temp_array.tolist())
+        faces =np.delete(faces ,np.arange(0 ,trim_num +1))
+
+    meshio_cells =[]
+    for key in cells:
+        if len(cells[key] ) >0:
+            meshio_cells.append((key ,cells[key]))
+
+    return meshio_cells
\ No newline at end of file