Actor not updated when increasing the number of points in a Line using setPoints about vedo HOT 3 CLOSED

The cause is that the Point data is updated but the line-data is not.
The following code would update the line-data as well:

# work-around
# (re-create the poly-line)

lines = L.poly.GetLines()
if lines:                                        # are we a lines-type actor
    n_points = L.NPoints()
    n_lines = lines.GetNumberOfCells()
    if n_lines != (n_points-1) :      # has the number of points changed?
        lines = vtk.vtkCellArray()    # Re-create the polyline.
        lines.InsertNextCell(n_points)
        for i in range(n_points):
              lines.InsertCellPoint(i)
        L.poly.SetLines(lines)

I could implement this in the SetPoints method and create a merge-request for this update, but wouldn't is have any side-effects?

from vedo.

Hi Ruben,
thanks for bringing up this issue, as you notice points are added but there is no way to know from inside setPoints() what is the cell connectivity for the point that is being added (either a line or some other polygon with other existing points)... so that would be a "side-effect": that would be only valid for lines.
Probably the easiest way is to recreate the longer line with Line(points).
Another possibility is to create a "line" made of N coincident points and then use setPoints() to modify it.

On the other hand this made me realize that a deletePoint() method might be useful.

Hope this helps.

NB: in Line(points) points can be a long list of point coordinates

from vedo.

Hi Marco,

thanks for the support.
The workaround works for me. And I do not see any robust modification either at this moment.

Should I close the issue or leave it open?

from vedo.