From b00505eca6566737820c9f4c8ff1c841533c3760 Mon Sep 17 00:00:00 2001
From: Tiffany Chhim <tiffany.chhim@kitware.com>
Date: Tue, 16 May 2023 12:06:25 +0200
Subject: [PATCH] FRD to VTK: Read the first timestep for the first data array

This is for illustration purposes. The actual results also contain
several timesteps.
---
 frd2vtk.py | 69 ++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 64 insertions(+), 5 deletions(-)

diff --git a/frd2vtk.py b/frd2vtk.py
index 8e6b2e5..d0d7bc6 100644
--- a/frd2vtk.py
+++ b/frd2vtk.py
@@ -1,6 +1,7 @@
 from vtk import vtkUnstructuredGrid
 from vtk import vtkXMLUnstructuredGridWriter
 from vtk import vtkPoints
+from vtk import vtkDoubleArray
 from vtk import VTK_QUADRATIC_HEXAHEDRON
 
 
@@ -11,10 +12,12 @@ with open("result.frd", 'r') as f:
     while line:
         if line[0:6] == '    1C':
             data['calc name'] = line[6:]
+
         elif line[0:6] == '    1U':
             if not 'user informations' in data:
                 data['user informations'] = []
             data['user informations'].append(line[6:])
+
         elif line[0:6] == '    2C':
             number_of_nodes = int(line[7:37])
             node_format = int(line[38:])
@@ -34,6 +37,7 @@ with open("result.frd", 'r') as f:
             line = f.readline()
             if line[0:3] != ' -3':
                 raise("Missing end record for node block: the line does not start with ' -3'.")
+
         elif line[0:6] == '    3C':
             number_of_elements = int(line[7:37])
             element_format = int(line[38:])
@@ -77,34 +81,89 @@ with open("result.frd", 'r') as f:
             if line[0:3] != ' -3':
                 print(line[0:3])
                 raise("Missing end record for element block: the line does not start with ' -3'.")
+
+        elif line[0:6] == '  100C':
+            number_of_values = int(line[24:36])
+
+            line = f.readline()
+            if line[0:3] != ' -4':
+                raise("Missing array info record for node block: the line does not start with ' -4'.")
+            name = line[3:17].strip()
+
+            number_of_components = 0
+            line = f.readline()
+            while line[0:3] == ' -5':
+                if line[5:8] != 'ALL':
+                    number_of_components = number_of_components + 1
+                line = f.readline()
+                array = {}
+                array[name] = []
+
+            for value_index in range(number_of_values):
+                if line[0:3] != ' -1':
+                    raise("Wrong record in data section: the line does not start with ' -1'.")
+                node_number = int(line[3:13])
+                values = []
+
+                for comp in range(number_of_components):
+                    values.append(float(line[(12*comp+13):(12*(comp+1)+13)]))
+
+                array[name].append([node_number, values])
+                line = f.readline()
+
+            data['arrays'] = array
+
+            # Stop reading here for this example
+            break
+
         line = f.readline()
 
 # Create VTK data object.
-vtk_unstructured_grid = vtkUnstructuredGrid()
+my_vtk_dataset = vtkUnstructuredGrid()
 
+# Create points.
 points = vtkPoints()
 nodes = data['nodes']
 node_map = {}
+
 for node_id in range(len(nodes)):
     points.InsertPoint(node_id, nodes[node_id][1])
     node_map[nodes[node_id][0]] = node_id
-vtk_unstructured_grid.SetPoints(points)
 
+my_vtk_dataset.SetPoints(points)
+
+# Create cells.
 elements = data['elements']
-vtk_unstructured_grid.Allocate(len(elements))
+my_vtk_dataset.Allocate(len(elements))
+
 for element_id in range(len(elements)):
     if elements[element_id][1] != 4:
         raise("Unsupported element type, he20 element supported only (type 4).")
+
     nodes = [node_map[id] for id in elements[element_id][4]]
     node_numbers = [nodes[0],nodes[1],nodes[2],nodes[3],
                     nodes[4],nodes[5],nodes[6],nodes[7],
                     nodes[8],nodes[9],nodes[10],nodes[11],
                     nodes[16],nodes[17],nodes[18],nodes[19],
                     nodes[12],nodes[13],nodes[14],nodes[15]]
-    vtk_unstructured_grid.InsertNextCell(VTK_QUADRATIC_HEXAHEDRON, 20, node_numbers)
+    my_vtk_dataset.InsertNextCell(VTK_QUADRATIC_HEXAHEDRON, 20, node_numbers)
+
+# Create data array.
+name = list(data['arrays'].keys())[0]
+array_values = data['arrays'][name]
+
+array = vtkDoubleArray()
+array.SetNumberOfComponents(3)
+array.SetNumberOfTuples(len(array_values))
+array.SetName(name)
+
+for values in array_values:
+    array.SetTuple(values[0] - 1, values[1])
+
+my_vtk_dataset.GetPointData().AddArray(array)
 
 # Write VTK data object.
 writer = vtkXMLUnstructuredGridWriter()
 writer.SetFileName("output.vtu")
-writer.SetInputData(vtk_unstructured_grid)
+writer.SetInputData(my_vtk_dataset)
 writer.Write()
-- 
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