fix(tubeFilter): update npts and change to global func

Author: WesleyTheGeolien

Sources/Filters/General/TubeFilter/index.js

@@ -635,14 +635,10 @@ function vtkTubeFilter(publicAPI, model) {
     let numStrips = 0;
     const inLinesData = inLines.getData();
     let npts = inLinesData[0];
-    const sidesShareVerticesMultiplier = model.sidesShareVertices ? 1 : 2;
     for (let i = 0; i < inLinesData.length; i += npts + 1) {
-      numNewPts += sidesShareVerticesMultiplier * npts * model.numberOfSides;
-      if (model.capping) {
-        numNewPts += 2 * model.numberOfSides;
-      }
-
       npts = inLinesData[i];
+
+      numNewPts = computeOffset(numNewPts, npts);
       numStrips +=
         (2 * npts + 1) * Math.ceil(model.numberOfSides / model.onRatio);
       if (model.capping) {