For vtkPoints
and other similar objects, when should I use Allocate
and when should I use SetNumberOfPoints
?
They pretty much do the same stuff. SetNumberOfPoints
calls SetNumberOfTuples
who calls Allocate
. Using SetNumberOfPoints
is easier to read so I would stick with that.
Allocate
just allocate the memory but leave the number of points to 0. So after that, you can use the InsertXXX
methods.
While SetNumberOfPoints
allocate and set the number of points, so after, you need to call SetPoint(index, x, y, z)
.
What’s the unit of a
in vtkPoints::Allocate(a)
and vtkPolyData::Allocate(a)
?
I would assume it is the number of values in the given vtkDataArray.
So for points you will do points->Allocate(nbPoints * 3)
.