fix bug when using cell data with to_mesh_state (#36)

* Update vtk.py

fixing typo where point data is used for cell data in `to_mesh_state`

* Update CHANGELOG.md

update changelog

Author: ericbdaniels

dash_vtk/utils/vtk.py

@@ -66,7 +66,7 @@ def to_mesh_state(dataset, field_to_keep=None):
     if c_array:
       dataRange = c_array.GetRange(-1)
       nb_comp = c_array.GetNumberOfComponents()
-      values = vtk_to_numpy(p_array).ravel()
+      values = vtk_to_numpy(c_array).ravel()
       js_types = to_js_type[str(values.dtype)]
       location = 'CellData'
 

docs/CHANGELOG.md

@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+* fix bug when using cell data with `to_mesh_state`
 
 ## [0.0.6] - 2021-02-22