[vtkusers] Draw a line when interact with the renderwindow

[Erkang Cheng]

Hi all:

Could anyone help me?

The story is that, I want to interact the window which display a image or
one slice of 3D data (like DICOM).

The operation is that when I click one point, and mouse move on the window,
then LeftButtonUp. These action could related to a line.

I want to save the positions of all the points on the line and draw this
line on the window.

I follow the example in InsightApplication titled "LiverTumorSegmentation".
In this application, I can get the point when I click on the window, also, I
can get the points when mouse move.

So, I want to draw this line on the window. How to do this?

My idea is that, suppose that there are two points p1 and p2, p1 is the
point I click on the window, when mouse move, p2 is current point, I want to
draw a line from p1 to p2. Then update p1 as p2. This could turn into a
line. I use this method in MFC which can draw a line.

But, I don't know how to draw a line in a vtkRenderWindow? what's the
coordinate of the vtkRenderWindow?

I look at the example about drawing a line in
"VTK/Examples/GeometricObjects/Display/Line". But, it doesn't look correct.


part of codes are:

Here, I test draw a line when I click on the renderwindow. The line is
supposed to from (10,10,0) to (50,50,0).  Every time when I click the line,
the line should not change.
But, when I add these codes in the click event, the line changes every time.
I wonder I do not catch the coordinate point. Could anyone help me figure
out the question?

     vtkLineSource * line = vtkLineSource::New();
    line->SetPoint1(10,10,0);
    line->SetPoint2(50,50,0);
    vtkPolyDataMapper * mapper = vtkPolyDataMapper::New();
    mapper->SetInput(line->GetOutput());

    line->Update();
    m_SphereActor->SetMapper(mapper);    //m_SphereActor is an instance of
vtkActor
   m_RenderWindow->Render();

Is there is example similar to my question?

Thanks a lot.
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