VTK/Examples/Cxx/Visualization/ImageTransparency

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VTK Examples Baseline Visualization TestImageTransparency.png
See also: VTK/Examples/Cxx/Images/Transparency and VTK/Examples/Cxx/Images/ImageStencil

ImageTransparency.cxx

#include <vtkVersion.h>
#include <vtkSmartPointer.h>
#include <vtkLookupTable.h>
#include <vtkImageData.h>
#include <vtkImageMapper3D.h>
#include <vtkImageMapToColors.h>
#include <vtkJPEGReader.h>
#include <vtkPointData.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkInteractorStyleImage.h>
#include <vtkRenderer.h>
#include <vtkImageActor.h>

static void CreateImage(vtkSmartPointer<vtkImageData> image);

int main(int, char*[])
{
  vtkSmartPointer<vtkImageData> image =
    vtkSmartPointer<vtkImageData>::New();
  CreateImage(image);
  
  // Create actor
  vtkSmartPointer<vtkImageActor> imageActor =
    vtkSmartPointer<vtkImageActor>::New();
#if VTK_MAJOR_VERSION <= 5
  imageActor->SetInput(image);
#else
  imageActor->GetMapper()->SetInputData(image);
#endif

  // Visualize
  vtkSmartPointer<vtkRenderer> renderer =
    vtkSmartPointer<vtkRenderer>::New();
  renderer->AddActor(imageActor);
  renderer->ResetCamera();

  vtkSmartPointer<vtkRenderWindow> renderWindow =
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);

  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  vtkSmartPointer<vtkInteractorStyleImage> style =
    vtkSmartPointer<vtkInteractorStyleImage>::New();

  renderWindowInteractor->SetInteractorStyle(style);

  renderWindowInteractor->SetRenderWindow(renderWindow);
  renderWindowInteractor->Initialize();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

void CreateImage(vtkSmartPointer<vtkImageData> image)
{
  // Specify the size of the image data
  image->SetDimensions(10,10,1);
#if VTK_MAJOR_VERSION <= 5
  image->SetNumberOfScalarComponents(4);
  image->SetScalarTypeToUnsignedChar();
#else
  image->AllocateScalars(VTK_UNSIGNED_CHAR,4);
#endif
  int* dims = image->GetDimensions();
  // int dims[3]; // can't do this

  std::cout << "Dims: " << " x: " << dims[0] << " y: " << dims[1] << " z: " << dims[2] << std::endl;

  // Fill every entry of the image with "2"
  for (int y = 0; y < dims[1]; y++)
    {
    for (int x = 0; x < dims[0]; x++)
      {
      
      unsigned char* pixel = static_cast<unsigned char*>(image->GetScalarPointer(x,y,0));
      pixel[0] = 255;
      pixel[1] = 255;
      pixel[2] = 255;
      if(x<5)
        {
        pixel[3] = 0;
        }
      else
        {
        pixel[3] = 255;
        }
      }
    }

}

Please try the new VTKExamples website.

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(ImageTransparency)

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

add_executable(ImageTransparency MACOSX_BUNDLE ImageTransparency.cxx)

if(VTK_LIBRARIES)
  target_link_libraries(ImageTransparency ${VTK_LIBRARIES})
else()
  target_link_libraries(ImageTransparency vtkHybrid vtkWidgets)
endif()

Download and Build ImageTransparency

Click here to download ImageTransparency. and its CMakeLists.txt file.

Once the tarball ImageTransparency.tar has been downloaded and extracted,

cd ImageTransparency/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:

./ImageTransparency

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