ExponentialCosine

VTKExamples/Cxx/VisualizationAlgorithms/ExponentialCosine


Description

Visualization of an exponential cosine function. Function values are indicated by surface displacement. Colors indicate derivative values.

Code

ExponentialCosine.cxx

//
// Brute force computation of Bessel functions. Might be better to create a
// filter (or source) object. Might also consider vtkSampleFunction.

#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkDataSetMapper.h>
#include <vtkDoubleArray.h>
#include <vtkNamedColors.h>
#include <vtkPlaneSource.h>
#include <vtkPointData.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>
#include <vtkTransform.h>
#include <vtkTransformPolyDataFilter.h>
#include <vtkWarpScalar.h>

int main( int , char *[] )
{
  int i, numPts;
  double x[3];
  double r, deriv;

  vtkSmartPointer<vtkNamedColors> colors =
    vtkSmartPointer<vtkNamedColors>::New();

  vtkSmartPointer<vtkRenderer> ren =
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renWin =
    vtkSmartPointer<vtkRenderWindow>::New();
  renWin->AddRenderer(ren);

  vtkSmartPointer<vtkRenderWindowInteractor> iren =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  iren->SetRenderWindow(renWin);

  // create plane to warp
  vtkSmartPointer<vtkPlaneSource> plane =
    vtkSmartPointer<vtkPlaneSource>::New();
  plane->SetResolution (300,300);

  vtkSmartPointer<vtkTransform> transform =
    vtkSmartPointer<vtkTransform>::New();
  transform->Scale(10.0,10.0,1.0);

  vtkSmartPointer<vtkTransformPolyDataFilter> transF =
    vtkSmartPointer<vtkTransformPolyDataFilter>::New();
  transF->SetInputConnection(plane->GetOutputPort());
  transF->SetTransform(transform);
  transF->Update();

  // compute Bessel function and derivatives. This portion could be
  // encapsulated into source or filter object.
  //
  vtkSmartPointer<vtkPolyData> input = transF->GetOutput();
  numPts = input->GetNumberOfPoints();

  vtkSmartPointer<vtkPoints> newPts =
    vtkSmartPointer<vtkPoints>::New();
  newPts->SetNumberOfPoints(numPts);

  vtkSmartPointer<vtkDoubleArray> derivs =
    vtkSmartPointer<vtkDoubleArray>::New();
  derivs->SetNumberOfTuples(numPts);

  vtkSmartPointer<vtkPolyData> bessel =
    vtkSmartPointer<vtkPolyData>::New();
  bessel->CopyStructure(input);
  bessel->SetPoints(newPts);
  bessel->GetPointData()->SetScalars(derivs);

  for (i=0; i<numPts; i++)
    {
    input->GetPoint(i,x);
    r = sqrt(static_cast<double>(x[0]*x[0]) + x[1]*x[1]);
    x[2] = exp(-r) * cos (10.0*r);
    newPts->SetPoint(i,x);
    deriv = -exp(-r) * (cos(10.0*r) + 10.0*sin(10.0*r));
    derivs->SetValue(i,deriv);
    }

  // warp plane
  vtkSmartPointer<vtkWarpScalar> warp =
    vtkSmartPointer<vtkWarpScalar>::New();
  warp->SetInputData(bessel);
  warp->XYPlaneOn();
  warp->SetScaleFactor(0.5);

  // mapper and actor
  vtkSmartPointer<vtkDataSetMapper> mapper =
    vtkSmartPointer<vtkDataSetMapper>::New();
  mapper->SetInputConnection(warp->GetOutputPort());
  double tmp[2];
  bessel->GetScalarRange(tmp);
  mapper->SetScalarRange(tmp[0],tmp[1]);

  vtkSmartPointer<vtkActor> carpet =
    vtkSmartPointer<vtkActor>::New();
  carpet->SetMapper(mapper);

  // assign our actor to the renderer
  ren->AddActor(carpet);
  ren->SetBackground(colors->GetColor3d("Beige").GetData());
  renWin->SetSize(640,480);

  // draw the resulting scene
  ren->ResetCamera();
  ren->GetActiveCamera()->Zoom(1.4);
  ren->GetActiveCamera()->Elevation(-55);
  ren->GetActiveCamera()->Azimuth(25);
  ren->ResetCameraClippingRange();
  renWin->Render();

  iren->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(ExponentialCosine)

find_package(VTK REQUIRED)
include(${VTK_USE_FILE})

add_executable(ExponentialCosine MACOSX_BUNDLE ExponentialCosine.cxx )

target_link_libraries(ExponentialCosine ${VTK_LIBRARIES})

Download and Build ExponentialCosine

Click here to download ExponentialCosine and its CMakeLists.txt file. Once the tarball ExponentialCosine.tar has been downloaded and extracted,

cd ExponentialCosine/build 

If VTK is installed:

cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

make

and run it:

./ExponentialCosine

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.