How to Pick Edge?

Hi!my current Polydata contains Line but not Ploy. I want to pick up the relevant information of such a red line. How should I do it?

(ps:I presuppose that I have the polyline selected and go to render)
Now,My current operation idea wants to be processed through CellPicker; because in my understanding, Line, PolyLine, and Poly can all be called Cells, but I have not succeeded in implementing them.
The data aspect has the index number corresponding to each line and the coordinate value of the vertex that a line contains.
I will humbly accept any suggestion you give me!
Thanks for everyone’s help!

Add an observer to the interactor, the object in the handler will be the interactor

def MousePress(iren , ev):
  renWin = iren.GetRenderWindow()
  pos = irenj.GetEventPosition()
  renderer = obj.FindPokedRenderer(pos[0], pos[1])

  x, y = iren.GetEventPosition()
  picker = vtk.vtkWorldPointPicker()
  picker.Pick(x, y, 0, renderer)
  worldPoint = picker.GetPickPosition()
  print('world point from vtkPropPicker: ', worldPoint)
  # Now you could add a small sphere to show the position
  sphere = vtk.vtkSphereSource()
  sphere.SetCenter(worldPoint[0], worldPoint[1], worldPoint[2])
  sphereMapper = vtk.vtkPolyDataMapper()
  sphereActor = vtk.vtkActor()
  sphereActor.GetProperty().SetColor(255, 0, 0)

You can store the last actor to remove the previous to avoid adding to many spheres. Was it something like this you had in mind?

Thanks for your replay!
But maybe I don’t think so;
What I mean is: I want to pick a line on the model, like this and the red line, but I don’t know how I can do it.
In other words, when I click on the model, I want to pick the line,what should I do?

You mean: when I click on the model, return me a world coordinate value, and render a sphere for labeling,this is my understanding.
I have considered using the coordinate value to judge the line segment before, but there will be some problems;
I’m wondering if there’s a better way.

What do you mean by judge the line segment? I wasn’t really sure what you were trying to achieve and thought that you might wanted the world position for a point in the scene. What do you mean by data aspect has an index number. Where is the red line?

If you want information about a cell that you pick, you can use a cell picker as shown here.

Change the example a bit:


I believe the author meant to have used this content type when creating the example. Press ‘w’ and you will see a wireframe with all edges of the picked triangle highlighted.

Did you check that hardware selector example ?


I guess this using the hardware accelerated picker. Picking using color codes. I used that for a standalone C++ application.

In general, it difficult to pick lines. They are thin. In the example I am referring to, you pick the cells and color both the facet and lines surrounding it. If the hardware accelerated example shown below is available I would look into that.

Thanks for your replay and suggestion!
I didn’t expect such a suitable example!
I am directly searching for relevant knowledge about Picker, I will continue to advance according to your suggestion!

Yes, I thought about using GPU Picker for picking like Three.js.
Due to lack of personal ability, there is no reasonable promotion.
I will continue to promote research, and welcome to continue to communicate if there is relevant progress.