FastSplatter

#include <vtkImageData.h>
#include <vtkImageShiftScale.h>
#include <vtkFastSplatter.h>
#include <vtkImageViewer2.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkSmartPointer.h>

#include <cmath>

const int SPLAT_IMAGE_SIZE = 100;

int main(int, char *[])
{
  // For the purposes of this example we'll build the splat image by
  // hand.

  vtkSmartPointer<vtkImageData> splatImage =
    vtkSmartPointer<vtkImageData>::New();
  splatImage->SetDimensions(SPLAT_IMAGE_SIZE, SPLAT_IMAGE_SIZE, 1);
  splatImage->AllocateScalars(VTK_FLOAT,1);

  for (int i = 0; i < SPLAT_IMAGE_SIZE; ++i)
  {
    for (int j = 0; j < SPLAT_IMAGE_SIZE; ++j)
    {
      double xCoord = 1 - fabs(  (i - SPLAT_IMAGE_SIZE/2)
                               / (SPLAT_IMAGE_SIZE/2.0) );
      double yCoord = 1 - fabs(  (j - SPLAT_IMAGE_SIZE/2)
                               / (SPLAT_IMAGE_SIZE/2.0) );

      splatImage->SetScalarComponentFromDouble(i, j, 0, 0,
                                               xCoord * yCoord );
    }
  }

  vtkSmartPointer<vtkPolyData> splatPoints =
    vtkSmartPointer<vtkPolyData>::New();
  vtkSmartPointer<vtkPoints> points =
    vtkSmartPointer<vtkPoints>::New();

  points->SetNumberOfPoints( 5 );
  double point[3];

  point[0] = 0;
  point[1] = 0;
  point[2] = 0;
  points->SetPoint( 0, point );

  point[0] = 1;
  point[1] = 1;
  point[2] = 0;
  points->SetPoint( 1, point );

  point[0] = -1;
  point[1] = 1;
  point[2] = 0;
  points->SetPoint( 2, point );

  point[0] = 1;
  point[1] = -1;
  point[2] = 0;
  points->SetPoint( 3, point );

  point[0] = -1;
  point[1] = -1;
  point[2] = 0;
  points->SetPoint( 4, point );

  splatPoints->SetPoints(points);

  vtkSmartPointer<vtkFastSplatter> splatter =
    vtkSmartPointer<vtkFastSplatter>::New();
  splatter->SetInputData(splatPoints );
  splatter->SetInputData(1, splatImage );
  splatter->SetOutputDimensions( 2*SPLAT_IMAGE_SIZE,
                                 2*SPLAT_IMAGE_SIZE,
                                 1 );

  // The image viewers and writers are only happy with unsigned char
  // images.  This will convert the floats into that format.
  vtkSmartPointer<vtkImageShiftScale> resultScale =
    vtkSmartPointer<vtkImageShiftScale>::New();
  resultScale->SetOutputScalarTypeToUnsignedChar();
  resultScale->SetShift(0);
  resultScale->SetScale(255);
  resultScale->SetInputConnection( splatter->GetOutputPort() );

  splatter->Update();
  resultScale->Update();

  // Set up a viewer for the image.  vtkImageViewer and
  // vtkImageViewer2 are convenient wrappers around vtkActor2D,
  // vtkImageMapper, vtkRenderer, and vtkRenderWindow.  All you need
  // to supply is the interactor and hooray, Bob's your uncle.
  vtkSmartPointer<vtkImageViewer2> imageViewer =
    vtkSmartPointer<vtkImageViewer2>::New();
  imageViewer->SetInputConnection( resultScale->GetOutputPort() );
  imageViewer->SetColorLevel(127);
  imageViewer->SetColorWindow(255);

  vtkSmartPointer<vtkRenderWindowInteractor> iren =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  imageViewer->SetupInteractor(iren);

  imageViewer->Render();
  imageViewer->GetRenderer()->ResetCamera();

  imageViewer->Render();
  iren->Start();

  return EXIT_SUCCESS;
}

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(FastSplatter)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonDataModel
  vtkImagingCore
  vtkImagingHybrid
  vtkInteractionImage
  vtkInteractionStyle
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping FastSplatter: ${VTK_NOT_FOUND_MESSAGE}")
  return ()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
  # old system
  include(${VTK_USE_FILE})
  add_executable(FastSplatter MACOSX_BUNDLE FastSplatter.cxx )
  target_link_libraries(FastSplatter PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(FastSplatter MACOSX_BUNDLE FastSplatter.cxx )
  target_link_libraries(FastSplatter PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS FastSplatter
    MODULES ${VTK_LIBRARIES}
    )
endif () 

cd FastSplatter/build 

cmake ..

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

make

./FastSplatter