[vtkusers] Picking and moving a vertex

[Geoframer]

Hi All,

Dean:
Thanks for pointing us to some helpful examples.

Meisam:
Thanks for providing us with an example of how to actually use the
GeneratePointId's. I already read about it, as I stated in the previous
mail, but an example is always easier to learn from. Perhaps your example
will help me understand how to use GeneratePointIdsOn in combination with
the vtkProgrammableGlyphFilter.

Regards - Geofram



On 6/15/07, Meisam Aliroteh <meisam.aliroteh at gmail.com> wrote:
>
> Hi All,
>
> Dean:
> thanks for pointing out the widget classes. I remembered needing some sort
> of transformation matrix to get point from one frame of referece to another
> but didn't know how to do this in vtk and the classes you pointed out were
> perfect example for it. Thanks again.
> So now I have obtained the motion vector, but do you know how can I
> constrain this motion to the view plain only. I guess what I need is to
> project the vector onto the view plane and use the projection as the new
> motion vector, is this right ?
>
> Geoframer, Henrik:
> You don't need to go through all that trouble to create many actors and
> then try to get their center , etc. I used to do that until I found the
> better way (use GeneratePointIdsOn() of the glygh class). Below is an
> example of how to do it in c++:
>
>
> #include "vtkPolyDataMapper.h"
> #include "vtkRenderWindow.h"
> #include "vtkActor.h"
> #include "vtkRenderer.h"
> #include "vtkRenderWindowInteractor.h"
> #include "vtkInteractorStyleTrackballCamera.h"
> #include "vtkProperty.h"
> #include "vtkPolyData.h"
> #include "vtkCell.h"
> #include "vtkCellData.h"
> #include " vtkSphereSource.h"
> #include "vtkGlyph3D.h"
> #include "vtkRendererCollection.h"
> #include "vtkCommand.h"
> #include "vtkCellPicker.h"
> #include "vtkPointData.h"
> #include "vtkIdTypeArray.h"
>
> class ActionHandler : public vtkCommand
> {
>     public:
>     static ActionHandler *New(){ return new ActionHandler; }
>     virtual void Execute(vtkObject *caller, unsigned long eventid, void
> *unUsed)
>     {
>         vtkRenderWindowInteractor *iren = (vtkRenderWindowInteractor
> *)caller;
>         vtkRenderer *ren = (vtkRenderer
> *)iren->GetRenderWindow()->GetRenderers()->GetItemAsObject(0);
>         vtkCellPicker *cellPicker = (vtkCellPicker *)iren->GetPicker();
>         int mouseX, mouseY;
>         iren->GetEventPosition(mouseX, mouseY);
>
>         int cellID = cellPicker->Pick(mouseX,mouseY,0,ren);
>         if ( cellID == 0 || (cellID = cellPicker->GetCellId()) == -1 )
>         {
>             return; // nothing is picked
>         }
>         else
>         {
>             vtkActor *pickedActor = cellPicker->GetActor();
>             vtkPolyData *pd = (vtkPolyData
> *)pickedActor->GetMapper()->GetInput();
>             vtkCell *pickedCell = pd->GetCell(cellID);
>             int pnt1 = pickedCell->GetPointId(0); // get one of the cell
> points
>             vtkIdTypeArray *InpPntIds = (vtkIdTypeArray
> *)pd->GetPointData()->GetArray("InputPointIds");
>             if ( InpPntIds )
>             {
>                 int id = (int)InpPntIds->GetTuple1(pnt1); // get the input
> point corresponding to this cell point
>                 printf("Picked vertex %d\n", id);
>             }
>         }
>     }
> };
>
> vtkPolyData *makeTempPoly()
> {
>     double pnts[4][3] = { {0,0,0}, {10,0,0}, {10,10,0}, {0,10,0} };
>     vtkPolyData *pd = vtkPolyData::New();
>     vtkPoints *points = vtkPoints::New();
>
>     pd->SetPoints( points );
>     pd->Allocate();
>     for(int i=0; i<4; i++)
>     {
>         points->InsertPoint(i, pnts[i][0], pnts[i][1], pnts[i][2]);
>         pd->InsertNextCell(VTK_VERTEX, 1, &i);
>     }
>
>     vtkIntArray *cell_scalars = vtkIntArray::New();
>     cell_scalars->SetNumberOfComponents(1);
>     for( int i=0; i<4; i++)
>         cell_scalars->InsertNextTuple1(i);
>     pd->GetCellData()->SetScalars(cell_scalars);
>
>     return pd;
> }
>
> int main()
> {
>     // Create graphics stuff
>     vtkRenderer *ren = vtkRenderer::New();
>     ren->SetBackground(0.1,0.2,0.4);
>
>     vtkRenderWindow *renWin = vtkRenderWindow::New();
>     renWin->SetSize(800,600);
>     renWin->AddRenderer(ren);
>
>     vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
>     iren->SetInteractorStyle( vtkInteractorStyleTrackballCamera::New() );
>     iren->SetRenderWindow(renWin);
>
>     vtkPolyData *pd1 = makeTempPoly();
>
>     vtkSphereSource *src = vtkSphereSource::New();
>     src->SetRadius(0.2);
>     src->SetThetaResolution(12);
>     src->SetPhiResolution(12);
>
>     vtkGlyph3D *glyph = vtkGlyph3D::New();
>     glyph->SetInput(pd1);
>     glyph->SetSource(src->GetOutput());
>     glyph->GeneratePointIdsOn();
>
>     vtkPolyDataMapper *mapper1 = vtkPolyDataMapper::New();
>     mapper1->SetInput( glyph->GetOutput() );
>     mapper1->ScalarVisibilityOff();
>     mapper1->GlobalImmediateModeRenderingOn();
>
>     vtkActor *actor1 = vtkActor::New();
>     actor1->SetMapper( mapper1 );
>     actor1->GetProperty()->SetColor(1,0,0);
>     actor1->GetProperty()->SetPointSize(4);
>
>     vtkCellPicker *cellPicker = vtkCellPicker::New();
>     cellPicker->SetTolerance(0.001);
>     iren->SetPicker(cellPicker);
>
>     ActionHandler *h = ActionHandler::New();
>     iren->AddObserver(vtkCommand::LeftButtonPressEvent, h, 1);
>
>     ren->AddActor(actor1);
>     iren->Initialize();
>     iren->Start();
>
>     return 0;
> }
>
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