[vtkusers] Display Coordinates Doesn't Change After Translation

[Wenlong Wang]

Hi, David

Sorry the last mail missed somthing.

The current situdation is, I set the transform like (1, 1, 0), and a new
polydata object was created and translated to another place. I catch the
new polydata with a pointer. In this case, I think the out coming of my
code should show that the display coordinates of points on the new sphere
has the value like ( X_originnal + X_translate, Y_original+Y_Translate, 0),
since I didn't translate it in Z direction.

But the result shows the X and Y coordinates were not changed at all, only
the Z has slight difference. Why is this happened? It really strange.

Thank you so much.

Wenlong

2011/10/31 Wenlong Wang <scc.wwl at gmail.com>

> Hi, David,
>
> Thank you for your help.
>
> Here is the code shows the problem I encountered.
>
>     *vtkSphereSource* s = vtkSphereSource::New();
>     s->Update();
>
>     vtkTransform* trans = vtkTransform::New();
>     trans->Translate(1, 1, 0);
>
>     vtkTransformPolyDataFilter* tf = vtkTransformPolyDataFilter::New();
>     tf->SetInputConnection(s->GetOutputPort());
>     tf->SetTransform(trans);
>     tf->Update();
>
>     vtkPolyDataMapper* originalMapper = vtkPolyDataMapper::New();
>     originalMapper->SetInputConnection(s->GetOutputPort());
>
>     vtkActor* originalActor = vtkActor::New();
>     originalActor->SetMapper(originalMapper);
>     originalActor->GetProperty()->SetColor(1, 0, 0);
>
>     vtkPolyDataMapper* transformedMapper = vtkPolyDataMapper::New();
>     transformedMapper->SetInputConnection(tf->GetOutputPort());
>
>     vtkActor* transdformedActor = vtkActor::New();
>     transdformedActor->SetMapper(transformedMapper);
>     transdformedActor->GetProperty()->SetColor(0 ,1, 0);
>
>     vtkCamera* camera = vtkCamera::New();
>     camera->SetPosition(0, 0, 5);
>     camera->SetViewUp(0, 1, 0);
>
>     vtkRenderer* ren = vtkRenderer::New();
>     ren->AddActor(originalActor);
>     ren->AddActor(transdformedActor);
>     ren->SetActiveCamera(camera);
>
>     vtkRenderWindow* renWin = vtkRenderWindow::New();
>     renWin->AddRenderer(ren);
>
>     vtkRenderWindowInteractor* iren = vtkRenderWindowInteractor::New();
>     iren->SetRenderWindow(renWin);
>
>     //------------------Start to convert the world coordinates to display
> coordinates--------------
>     vtkPoints* points = vtkPoints::New();
>     vtkPolyData* polydata = vtkPolyData::New();
>
>     polydata = tf->GetOutput();
>     points = polydata->GetPoints();
>
>     double p[3], r[3];
>     for (int i = 0; i< 50; i++)
>     {
>         points->GetPoint(i, p);
>         ren->SetWorldPoint(p);
>         ren->WorldToDisplay();
>         ren->GetDisplayPoint(r);
>     }**
>     renWin->Render();
>     iren->Start();*
>
> On the screen, the sphere did translate to another place. However, when I
> check the display coordinates store in point *r*, I found the X and Y are
> not changed, only Z has slight difference.
>
> Thank you again for your time.
>
> Wenlong
>
>
> 2011/10/30 David Doria <daviddoria at gmail.com>
>
>> On Sat, Oct 29, 2011 at 1:47 PM, Wenlong Wang <scc.wwl at gmail.com> wrote:
>>
>>> Hi David,
>>>
>>> I tried the example about vtkTransformPolyDataFilter and applied it to
>>> my actor. But seems the coordinates didn't change in the way I discribed in
>>> my earlier mail.
>>>
>>> So is that because I didn't use it right? Or I should use other methods
>>> to get access to the new dataset generated by vtkTransformPolyDataFilter?
>>>
>>> Thank you very much.
>>>
>>> Long
>>
>>
>> I suggest you send the smallest possible compilable code that you can to
>> demonstrate the problem. Something like simply display a vtkSphereSource.
>> Describe the behavior the code produces, and the behavior that you are
>> aiming for.
>>
>> David
>>
>
>
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