[vtkusers] Clipping Planes

[John Biddiscombe]

After calling AddDisplacement(...) you are calling resetCameralippingRage() yes? If not. try it.

JB
  ----- Original Message ----- 
  From: James Robinson 
  To: Vtk Users 
  Sent: Wednesday, August 11, 2004 11:24 AM
  Subject: [vtkusers] Clipping Planes


  Dear All,

   

  I am having trouble (again) with clipping planes. I am trying to create a viewer to view results of an FE analysis. Part of the results are the displacements at the nodes of the finite element mesh. I read in the FE mesh into a vtkUnstructuredGrid with the displacements as a vector field. I then create a displaced geometry by adding them to the vtkUnstructuredGrid geometry as follows:

   

  void CSampleDoc::AddDisplacement(float factor)

  {   vtkFloatArray *pDisplacement = (vtkFloatArray*)this->pUnstructuredGrid->GetPointData()->GetVectors() ;

   

              vtkPoints* pNodalGeometry = this->pUnstructuredGrid->GetPoints() ;

   

              if (pDisplacement==NULL)

              { AfxMessageBox("No displacement set") ;

                return ;

              }

   

   

              float newcoords[3] ;

              float* x ;

              float* delta ;

   

              for (int i = 0; i < pNodalGeometry->GetNumberOfPoints(); i++)

              {  

                 x = pNodalGeometry->GetPoint(i) ;

         delta = pDisplacement->GetTuple(i) ;

                 for (int j = 0; j < 3; j++)

         { newcoords[j] = x[j] + factor*delta[j] ;

                 }

         pNodalGeometry->SetPoint(i,newcoords) ;

              }

      this->pUnstructuredGrid->Update() ;

      this->pGeometry->SetInput(pUnstructuredGrid) ;

      this->pMeshMapper->SetInput(pGeometry->GetOutput());

      this->pMeshMapper->Update() ;

      this->pMeshActor->SetMapper(this->pMeshMapper) ;

  }

   

  This works (with some other quirky behaviour which I have circumvented). But a problem that I am having difficulty with is that the clipping planes remain as if the geometry hadn't been altered. Thus, as I rotate the object (in trackball camera mode) the displaced object disappears. I have checked the bounds of the viewable objects (using Renderer->ComputeVisiblePropBounds(bounds) ;) and they are unaltered - thus all the AutoClipping is thrown out of whack. It may very well be that (a) I am doing things that are not meant to be catered for in vtk or (b) there is a better (preferably simpler) way of achieving this effect. 

   

  All suggestions gratefully welcomed.

   

  Jim

   

  James C Robinson, PhD, Chartered Engineer,

  +     42 Rivergrove,

           Glanmire,

           Co. Cork,

           Eire

  '     +353 21 4822028

           +353 87 2393010

  6      +353 21 4822028

  -    j.robinson at kepler-systems.com 

   



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