ColorCellsWithRGB

Description¶

This example shows how to assign specific colors to individual cells of a vtkPolyData. This example stores the vtkCellData as rgb triples in a vtkUnsignedCharArray.

Seealso

The example ColorCells creates a vtkCellData with a vtkFloatArray that contains index values for a vtkLookupTable.

Other languages

See (Java)

Question

If you have a question about this example, please use the VTK Discourse Forum

Code¶

ColorCellsWithRGB.cxx

#include <vtkActor.h>
#include <vtkCellData.h>
#include <vtkMinimalStandardRandomSequence.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPlaneSource.h>
#include <vtkPolyDataMapper.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkUnsignedCharArray.h>

int main(int, char*[])
{
  // Provide some geometry.
  int resolutionX = 5;
  int resolutionY = 3;

  vtkNew<vtkPlaneSource> aPlane;
  aPlane->SetXResolution(resolutionX);
  aPlane->SetYResolution(resolutionY);
  aPlane->Update();

  // Create cell data.
  vtkNew<vtkUnsignedCharArray> cellData;
  cellData->SetNumberOfComponents(3);
  cellData->SetNumberOfTuples(aPlane->GetOutput()->GetNumberOfCells());

  vtkNew<vtkMinimalStandardRandomSequence> randomSequence;
  randomSequence->SetSeed(8775070);
  auto min_r = 64.0;
  auto max_r = 255.0;
  for (int i = 0; i < aPlane->GetOutput()->GetNumberOfCells(); i++)
  {
    double rgb[3];
    for (auto j = 0; j < 3; ++j)
    {
      rgb[j] = randomSequence->GetRangeValue(min_r, max_r);
      randomSequence->Next();
    }
    cellData->InsertTuple(i, rgb);
  }

  aPlane->GetOutput()->GetCellData()->SetScalars(cellData);

  // Setup actor and mapper.
  vtkNew<vtkNamedColors> colors;

  vtkNew<vtkPolyDataMapper> mapper;
  mapper->SetInputConnection(aPlane->GetOutputPort());

  vtkNew<vtkActor> actor;
  actor->SetMapper(mapper);

  // Setup render window, renderer, and interactor.
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("ColorCellsWithRGB");
  vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
  renderWindowInteractor->SetRenderWindow(renderWindow);
  renderer->AddActor(actor);
  renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());
  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt¶

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(ColorCellsWithRGB)

find_package(VTK COMPONENTS 
  CommonColor
  CommonCore
  CommonDataModel
  FiltersSources
  InteractionStyle
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "ColorCellsWithRGB: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(ColorCellsWithRGB MACOSX_BUNDLE ColorCellsWithRGB.cxx )
  target_link_libraries(ColorCellsWithRGB PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS ColorCellsWithRGB
  MODULES ${VTK_LIBRARIES}
)

Download and Build ColorCellsWithRGB¶

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

cd ColorCellsWithRGB/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:

./ColorCellsWithRGB

WINDOWS USERS

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