[vtkusers] Intersection of cylinders

[Quang Tran]

Hello Peter,
You can do it as the following code:

  // Set up a transformation for the first cylinder (for intersection
testing purpose)
  vtkSmartPointer<vtkTransform> pTrans =
vtkSmartPointer<vtkTransform>::New();
  pTrans->RotateZ(90);

  vtkSmartPointer<vtkCylinder> pCylinder1 =
vtkSmartPointer<vtkCylinder>::New();
  pCylinder1->SetCenter(0, 0, 0);
  pCylinder1->SetRadius(30);
  pCylinder1->SetTransform(pTrans);

  // Sampling for the purpose to get the surface of cylinder1 later
  vtkSmartPointer<vtkSampleFunction> cylinder1Sample =
vtkSmartPointer<vtkSampleFunction>::New();
  cylinder1Sample->SetImplicitFunction(pCylinder1);
  cylinder1Sample->SetModelBounds(-200, 200, -200, 200, -200, 200);
  cylinder1Sample->SetSampleDimensions(100, 100, 100);
  cylinder1Sample->ComputeNormalsOff();
  cylinder1Sample->Update();

  vtkSmartPointer<vtkContourFilter> pContourFilter =
vtkSmartPointer<vtkContourFilter>::New();
  pContourFilter->SetInput(cylinder1Sample->GetOutput());
  pContourFilter->SetValue(0, 0.0);
  pContourFilter->Update();

  vtkSmartPointer<vtkPolyData> pCylinderSurf =
vtkSmartPointer<vtkPolyData>::New();
  pCylinderSurf = pContourFilter->GetOutput(); //  surface of cylinder1

  // Cylinder2 working with the role as an implicit function
  vtkSmartPointer<vtkCylinder> pCylinder2 =
vtkSmartPointer<vtkCylinder>::New();
  double aCenter[3];
  pCylinder2->SetRadius(30);

  // Clip cylinder1 here...
  vtkSmartPointer<vtkClipPolyData> clipper =
vtkSmartPointer<vtkClipPolyData>::New();
  clipper->SetInput(pCylinderSurf);
  clipper->SetClipFunction(pCylinder2);
  clipper->GenerateClipScalarsOn();
  clipper->GenerateClippedOutputOn();
  clipper->SetValue(0.0);

  vtkSmartPointer<vtkPolyData> intersectSurf =
vtkSmartPointer<vtkPolyData>::New();
  intersectSurf = clipper->GetClippedOutput(); // ==> this result is what
you need

--
/Quang


2011/11/6 Peter <peter-dpl at pre-dev.de>

> Hi Quang,
>
> thanks for your answer and sorry for my delayed response. I have to admit
> that I'm new to vtk so please apologize, that I don't understand everything.
>
> Do you mean, that I have to model both cylinders as vtkCylinder and also
> as vtkCylinderSource? And by using the vtkClipPolyData I will get the
> "correct" data I need as input for vtkImplicitBoolean?
>
> Greetings,
> Peter
>
> Am 01.11.2011 um 03:03 schrieb Quang Tran:
>
> > Hi,
> > You should use vtkImplicitBoolean and vtkClipPolyData to do this task.
> One of cylinder must be modeling to implicit function (you should use
> vtkCylinder and make any transform if necessary), set this implicit
> function as an input of the clipper (vtkClipPolydata), see SetClipFunction;
> the other cylinder is input parameter of SetInput function of clipper.
> After that you will have a result of this clipper as vtkPolyData. I think
> this result is what you need.
> >
> > You should use vtkCylinder rather than vtkCylinderSource because
> vtkCylinder is an implicit function and can use for clipping.
> >
> > /Quang
> >
>
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