docs(lookuptable, appendpolydata): document some implementation choices

document some implementation choices

Author: joannacirillo

Sources/Common/Core/LookupTable/index.js

@@ -338,6 +338,8 @@ export function extend(publicAPI, model, initialValues = {}) {
   vtkScalarsToColors.extend(publicAPI, model, initialValues);
 
   // Internal objects initialization
+  // model.table needs to be instanciated manually if it is an array to not call
+  // setTable in that case
   if (Array.isArray(initialValues.table)) {
     model.table = initialValues.table;
     delete initialValues.table;

Sources/Filters/General/AppendPolyData/index.js

@@ -10,6 +10,7 @@ const { vtkErrorMacro } = macro;
 
 function offsetCellArray(typedArray, offset) {
   let currentIdx = 0;
+  // No data to shift
   if (!typedArray) return {};
   return typedArray.map((value, index) => {
     if (index === currentIdx) {