text: /*=========================================================================
  
    Program:   Visualization Toolkit
    Module:    SGrid.cxx
  
    Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
    All rights reserved.
    See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
  
       This software is distributed WITHOUT ANY WARRANTY; without even
       the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
       PURPOSE.  See the above copyright notice for more information.
  
  =========================================================================*/
  // This example shows how to manually create a structured grid.
  // The basic idea is to instantiate vtkStructuredGrid, set its dimensions,
  // and then assign points defining the grid coordinate. The number of
  // points must equal the number of points implicit in the dimensions
  // (i.e., dimX*dimY*dimZ). Also, data attributes (either point or cell)
  // can be added to the dataset.
  //
  //
  #include "vtkActor.h"
  #include "vtkCamera.h"
  #include "vtkFloatArray.h"
  #include "vtkHedgeHog.h"
  #include "vtkMath.h"
  #include "vtkPointData.h"
  #include "vtkPoints.h"
  #include "vtkPolyDataMapper.h"
  #include "vtkProperty.h"
  #include "vtkRenderWindow.h"
  #include "vtkRenderWindowInteractor.h"
  #include "vtkRenderer.h"
  #include "vtkStructuredGrid.h"
  
  int main()
  {
    int i, j, k, kOffset, jOffset, offset;
    float x[3], v[3], rMin=0.5, rMax=1.0, deltaRad, deltaZ;
    float radius, theta;
    static int dims[3]={13,11,11};
  
    // Create the structured grid.
    vtkStructuredGrid *sgrid = vtkStructuredGrid::New();
        sgrid->SetDimensions(dims);
  
    // We also create the points and vectors. The points
    // form a hemi-cylinder of data.
    vtkFloatArray *vectors = vtkFloatArray::New();
      vectors->SetNumberOfComponents(3);
      vectors->SetNumberOfTuples(dims[0]*dims[1]*dims[2]);
    vtkPoints *points = vtkPoints::New();
      points->Allocate(dims[0]*dims[1]*dims[2]);
  
    deltaZ = 2.0 / (dims[2]-1);
    deltaRad = (rMax-rMin) / (dims[1]-1);
    v[2]=0.0;
    for ( k=0; k<dims[2]; k++)
      {
      x[2] = -1.0 + k*deltaZ;
      kOffset = k * dims[0] * dims[1];
      for (j=0; j<dims[1]; j++)
        {
        radius = rMin + j*deltaRad;
        jOffset = j * dims[0];
        for (i=0; i<dims[0]; i++)
          {
          theta = i * vtkMath::RadiansFromDegrees(15.0);
          x[0] = radius * cos(theta);
          x[1] = radius * sin(theta);
          v[0] = -x[1];
          v[1] = x[0];
          offset = i + jOffset + kOffset;
          points->InsertPoint(offset,x);
          vectors->InsertTuple(offset,v);
          }
        }
      }
    sgrid->SetPoints(points);
    points->Delete();
    sgrid->GetPointData()->SetVectors(vectors);
    vectors->Delete();
  
    // We create a simple pipeline to display the data.
    vtkHedgeHog *hedgehog = vtkHedgeHog::New();
        hedgehog->SetInputData(sgrid);
        hedgehog->SetScaleFactor(0.1);
  
    vtkPolyDataMapper *sgridMapper = vtkPolyDataMapper::New();
        sgridMapper->SetInputConnection(hedgehog->GetOutputPort());
    vtkActor *sgridActor = vtkActor::New();
        sgridActor->SetMapper(sgridMapper);
        sgridActor->GetProperty()->SetColor(0,0,0);
  
    // Create the usual rendering stuff
    vtkRenderer *renderer = vtkRenderer::New();
    vtkRenderWindow *renWin = vtkRenderWindow::New();
      renWin->AddRenderer(renderer);
  
    vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
      iren->SetRenderWindow(renWin);
  
    renderer->AddActor(sgridActor);
    renderer->SetBackground(1,1,1);
    renderer->ResetCamera();
    renderer->GetActiveCamera()->Elevation(60.0);
    renderer->GetActiveCamera()->Azimuth(30.0);
    renderer->GetActiveCamera()->Zoom(1.25);
    renWin->SetSize(300,300);
  
    // interact with data
    renWin->Render();
    iren->Start();
  
    renderer->Delete();
    renWin->Delete();
    iren->Delete();
    sgrid->Delete();
    hedgehog->Delete();
    sgridMapper->Delete();
    sgridActor->Delete();
  
    return 0;
  }
  