[vtkusers] tdinar at gmail.com

[tariq]

Hi, I am a newbie to vtk, and I have been trying to visualize an unstructured
grid with the aid of vtkGeometryFilter to convert a polyhedron 
(unStructuredGrid) into vtkPolyData. Then compute the Normals and use a
Lookup table to plot the data. The one polyhedron in my code would not show
up.  The code is pasted below and I am all ears. Thanks. TQ.

#include <vtkSmartPointer.h>
#include <vtkRenderer.h>
#include <vtkUnstructuredGrid.h>
#include <vtkPolyhedron.h>
#include <vtkCellArray.h>
#include <vtkPointData.h>
#include <vtkCellData.h>
#include <vtkIdList.h>
#include <vtkPoints.h>
#include <vtkDataArray.h>
#include <vtkConnectivityFilter.h>
#include <vtkGeometryFilter.h>
#include <vtkPolyDataMapper.h>
#include <vtkPolyDataNormals.h>
#include <vtkActor.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkLookupTable.h>



int main( int, char*[] )
{
    // create polyhedron (cube)
    vtkIdType pointIds[8] = {0, 1, 2, 3, 4, 5, 6, 7};
    
    vtkSmartPointer<vtkPoints> points =
    vtkSmartPointer<vtkPoints>::New();
    points->InsertNextPoint(-1.0,-1.0,-1.0);
    points->InsertNextPoint( 1.0,-1.0,-1.0);
    points->InsertNextPoint( 1.0, 1.0,-1.0);
    points->InsertNextPoint(-1.0, 1.0,-1.0);
    points->InsertNextPoint(-1.0,-1.0, 1.0);
    points->InsertNextPoint( 1.0,-1.0, 1.0);
    points->InsertNextPoint( 1.0, 1.0, 1.0);
    points->InsertNextPoint(-1.0, 1.0, 1.0);
    
    vtkSmartPointer<vtkCellArray> faces =
    vtkSmartPointer<vtkCellArray>::New();
    vtkIdType face0[4] = {0, 3, 2, 1};
    vtkIdType face1[4] = {0, 4, 7, 3};
    vtkIdType face2[4] = {4, 5, 6, 7};
    vtkIdType face3[4] = {5, 1, 2, 6};
    vtkIdType face4[4] = {0, 1, 5, 4};
    vtkIdType face5[4] = {2, 3, 7, 6};
    
    faces->InsertNextCell(4, face0);
    faces->InsertNextCell(4, face1);
    faces->InsertNextCell(4, face2);
    faces->InsertNextCell(4, face3);
    faces->InsertNextCell(4, face4);
    faces->InsertNextCell(4, face5);
    
    vtkSmartPointer<vtkUnstructuredGrid> ugrid =
    vtkSmartPointer<vtkUnstructuredGrid>::New();
    ugrid->SetPoints(points);
    ugrid->InsertNextCell(
                          VTK_POLYHEDRON, 8, pointIds,
                          6, faces->GetPointer());
    // Extract poly data from unsturctured Grid

    vtkSmartPointer<vtkConnectivityFilter> Filter1=
    vtkSmartPointer<vtkConnectivityFilter>::New();
    
    Filter1->SetInputData(ugrid);
    Filter1->Update(0);
    
    vtkSmartPointer<vtkGeometryFilter> Filter2=
    vtkSmartPointer<vtkGeometryFilter>::New();
    

    Filter2->SetInputConnection(0,Filter1->GetOutputPort(0));
    Filter2->Update(0);
    
    // Calculate normals
    
    vtkSmartPointer<vtkPolyDataNormals> normals =
    vtkSmartPointer<vtkPolyDataNormals>::New();
    
    normals->SetFeatureAngle(60);

    normals->SetInputConnection(0,Filter2->GetOutputPort(0));
    
    normals->Update(0);
    
    //Setup lookup table
    vtkSmartPointer<vtkLookupTable> lut=
    vtkSmartPointer<vtkLookupTable>::New();
    
    lut->SetHueRange(0.0, 100);
    
    // initiate mapper
    
    vtkSmartPointer<vtkPolyDataMapper> mapper=
    vtkSmartPointer<vtkPolyDataMapper>::New();
    
    mapper->SetInputConnection(0,normals->GetOutputPort(0));
    mapper->SetLookupTable(lut);
    mapper->SetScalarRange(0.12, 0.6);
    
    
    vtkSmartPointer<vtkActor> actor=
    vtkSmartPointer<vtkActor>::New();
    
    // Initiate Actor
    
    actor->SetMapper(mapper);
    actor->SetPosition(0.0, 0.0, 0.0);

    // Create a renderer, render window, and interactor
    vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
    renderer->ResetCamera();
    renderer->ResetCameraClippingRange();
    
    vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
    
    renderWindow->AddRenderer(renderer);
    
    vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
    renderWindowInteractor->SetRenderWindow(renderWindow);
    
    // Add the actor to the scene
    renderer->AddActor(actor);
    renderer->SetBackground(.2, .3, .4);
    
    // Render and interact
    renderWindow->Render();
    renderWindowInteractor->Start();

 
    
    return EXIT_SUCCESS;
}





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