[vtkusers] Show edges with picker

[nmitreski]

Finally some kind of solution. I' m getting edges from one cell (triangle).
Here is solution

#include "vtkPolyData.h"
#include "vtkConeSource.h"
#include "vtkPolyDataMapper.h"
#include "vtkCellArray.h"
#include "vtkActor.h"
#include "vtkRenderer.h"
#include "vtkRenderWindow.h"
#include "vtkRenderWindowInteractor.h"
#include "vtkProperty.h"
#include "vtkPoints.h"

int main(int argc, char *argv[])
{
	vtkConeSource *cone = vtkConeSource::New();
	cone->SetRadius(1.0);
	cone->SetHeight(3.0);
	cone->SetResolution(8);
	cone->CappingOff();

	vtkPolyData *mesh = vtkPolyData::New();
	mesh = cone->GetOutput();
	mesh->Update(); //important part
	mesh->BuildLinks();

	vtkPolyData *contour = vtkPolyData::New();
	contour->SetPoints(mesh->GetPoints());

	vtkPoints *points = vtkPoints::New();
	points = mesh->GetPoints();
	vtkIdType num_pts = points->GetNumberOfPoints();
	cout<<"Number of Points = "<<num_pts<<endl;

	vtkCellArray *lines = vtkCellArray::New();

	vtkIdType npts, *pts;
	mesh->GetCellPoints(4, npts, pts);
	cout<<"npts = "<<npts<<endl;
	cout<<"pts[0] = "<<pts[0]<<endl;
	cout<<"pts[1] = "<<pts[1]<<endl;
	cout<<"pts[2] = "<<pts[2]<<endl;

	vtkIdType ids[2];
	ids[0] = pts[0]; ids[1] = pts[1];
	lines->InsertNextCell(2, ids);

	ids[0] = pts[1]; ids[1] = pts[2];
	lines->InsertNextCell(2, ids);

	ids[0] = pts[2]; ids[1] = pts[0];
	lines->InsertNextCell(2, ids);

	contour->SetLines(lines);

	vtkPolyDataMapper *coneMapper = vtkPolyDataMapper::New();
	coneMapper->SetInput(cone->GetOutput());

	vtkPolyDataMapper *contourMapper = vtkPolyDataMapper::New();
	contourMapper->SetInput(contour);

	vtkActor *coneActor = vtkActor::New();
	coneActor->SetMapper(coneMapper);

	vtkActor *contourActor = vtkActor::New();
	contourActor->SetMapper(contourMapper);
	contourActor->GetProperty()->SetColor(1, 0, 0);

	vtkRenderer *ren = vtkRenderer::New();
	vtkRenderWindow *win = vtkRenderWindow::New();
	win->AddRenderer(ren);
	vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
	iren->SetRenderWindow(win);
	ren->AddActor(coneActor);
	ren->AddActor(contourActor);
	ren->SetBackground(0.1, 0.2, 0.4);

	iren->Initialize();
	win->Render();
	iren->Start();

	//deleting styff
	cone->Delete();
	coneMapper->Delete();
	coneActor->Delete();

	//new polydata
	contour->Delete();
	lines->Delete();
	contourMapper->Delete();
	contourActor->Delete();

	ren->Delete();
	win->Delete();
	iren->Delete();

	return 0;
}


nmitreski wrote:
> 
> Thanks for advice. You give me some direction for solving problem. It has
> some little problem in line
> 
> vtkIdType ids[2];
> ids[0] = pts[0]; ids[1] = pts[1];
> 
> when debugging the code, I receive error message in this line, maybe
> previous command
> 
>  mesh->GetCellPoints( cell_id, npts, pts );
> 
> did not give wanted values for npts and pts.
> 
> Bob-139 wrote:
>> 
>> 2008/1/16, nmitreski <nimitreski at gmail.com>:
>>>
>>> Hi.
>>> I have some problem. I'm trying to display edges of picked cell using
>>> cell
>>> picker. I'm trying that on cone (vtkConeSource), and I just like to
>>> display
>>> edges from picked cell. (something like edges from just 1 triangle)
>>> Can somebody help me? If you have some working example for picking cells
>>> in
>>> C++, please send it to me.
>>>
>> 
>> I think that you have to add another actor to the renderer, or better
>> make use of a vtkAssembly. The new polydata from which you are mapping
>> should have only three lines contouring the cell. The actual code is
>> something like the following:
>> 
>> 
>> // mesh is the input polyData
>> // here picker is a vtkCellPicker instance.
>> // giving a cell id you want to highlight,
>> // picked from x, y display position.
>> 
>> 
>> vtkPolyData* contour= vtkPolyData::New();
>> vtkCellArray* lines= vtkCellArray::New();
>> vtkAssembly* assem= vtkAssembly::New();
>> vtkPolyDataMapper* mapper1= vtkPolyDataMapper::New();
>> vtkPolyDataMapper* mapper2= vtkPolyDataMapper::New();
>> vtkActor* principalActor= vtkActor::New();
>> vtkActor* contourActor= vtkActor::New();
>> principalActor->SetMapper( mapper1 );
>> principalActor->SetMapper( mapper2 );
>> mapper1->SetInput( mesh );
>> mapper2->SetInput( contour );
>> 
>> assem->AddPart( principalActor );
>> assem->AddPart( contourActor );
>> 
>> contour->SetPoints( mesh->GetPoints() );
>> contour->SetLines( lines );
>> 
>> vtkCellPicker* picker= vtkCellPicker::New();
>> int is_pick= picker->Pick( (float)x, (float)y, 1.0, renderer );
>> 
>> if( ! is_pick )
>> {
>>    return;
>> }
>> 
>> vtkIdType cell_id= picker->GetCellId();
>> 
>> vtkIdType npts, *pts;
>> mesh->BuildLinks();
>> mesh->GetCellPoints( cell_id, npts, pts );
>> 
>> assert( npts == 3 ):
>> 
>> vtkIdType ids[2];
>> ids[0]= pts[0]; ids[1]= pts[1];
>> lines->InsertNextCell( 2, ids );
>> 
>> ids[0]= pts[1]; ids[1]= pts[2];
>> lines->InsertNextCell( 2, ids );
>> 
>> ids[0]= pts[2]; ids[1]= pts[0];
>> lines->InsertNextCell( 2, ids );
>> 
>> renderer->AddActor( assem );
>> 
>> // then the ...->Delete() stuff
>> 
>> HTH.
>> Bob.
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>> 
> 
> 

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