separating vtk from results

we should discuss the naming!

python/damask/ktv.py

@@ -0,0 +1,57 @@
+import numpy as np
+import vtk
+#from vtk.util import numpy_support
+
+class VTK: # capitals needed/preferred?
+    """
+    Manage vtk files.
+
+    tbd
+    """
+
+    def __init__(self,geom):
+        """tbd."""
+        self.geom = geom
+
+    @staticmethod
+    def from_rectilinearGrid(grid,size,origin=np.zeros(3)):
+        coordArray = [vtk.vtkDoubleArray(),vtk.vtkDoubleArray(),vtk.vtkDoubleArray()]
+        for dim in [0,1,2]:
+            for c in np.linspace(0,size[dim],1+grid[dim]):
+                coordArray[dim].InsertNextValue(c)
+
+        geom = vtk.vtkRectilinearGrid()
+        geom.SetDimensions(*(grid+1))
+        geom.SetXCoordinates(coordArray[0])
+        geom.SetYCoordinates(coordArray[1])
+        geom.SetZCoordinates(coordArray[2])
+        
+        return VTK(geom)
+
+
+    @staticmethod
+    def from_unstructuredGrid(nodes,connectivity,elem):
+        geom = vtk.vtkUnstructuredGrid()
+        geom.SetPoints(nodes)
+        geom.Allocate(connectivity.shape[0])
+
+        if   elem == 'TRIANGLE':
+            vtk_type = vtk.VTK_TRIANGLE
+            n_nodes = 3
+        elif elem == 'QUAD':
+            vtk_type = vtk.VTK_QUAD
+            n_nodes = 4
+        elif elem == 'TETRA':
+            vtk_type = vtk.VTK_TETRA
+            n_nodes = 4
+        elif elem == 'HEXAHEDRON':
+            vtk_type = vtk.VTK_HEXAHEDRON
+            n_nodes = 8
+
+        for i in connectivity:
+            geom.InsertNextCell(vtk_type,n_nodes,i-1)
+
+        return VTK(geom)
+
+    def write(self,fname):
+        print('tbd',fname)