ColoredSphere

Description¶

This demonstrates a simple visualization pipeline. A polygonal representation of a sphere is created with the source object (vtkSphereSource). The sphere is passed through a filter (vtkElevationFilter) that computes the height of each point of the sphere above a plane. The plane is perpendicular to the z-axis, and passes through the point (0,0,-1). The data is finally mapped (vtkDataSetMapper) through a lookup table. The mapping process converts height value into colors, and interfaces the sphere geometry to the rendering library. The mapper is assigned to an actor, and then the actor is displayed.

The execution of the pipeline occurs implicitly when we render the actor. Each actor asks its mapper to update itself. The mapper in turn asks its input to update itself. This process continues until a source object is encountered. Then the source will execute if modified since the last render.

Info

See Figure 4-19 in Chapter 4 the VTK Textbook.

Other languages

See (Python), (PythonicAPI), (Java)

Question

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

Code¶

ColoredSphere.cxx

#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkDataSetMapper.h>
#include <vtkElevationFilter.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSphereSource.h>

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renWin;
  renWin->AddRenderer(renderer);
  vtkNew<vtkRenderWindowInteractor> iren;
  iren->SetRenderWindow(renWin);

  vtkNew<vtkSphereSource> sphere;
  sphere->SetPhiResolution(12);
  sphere->SetThetaResolution(12);

  vtkNew<vtkElevationFilter> colorIt;
  colorIt->SetInputConnection(sphere->GetOutputPort());
  colorIt->SetLowPoint(0, 0, -1);
  colorIt->SetHighPoint(0, 0, 1);

  vtkNew<vtkDataSetMapper> mapper;
  mapper->SetInputConnection(colorIt->GetOutputPort());

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

  renderer->AddActor(actor);
  renderer->SetBackground(colors->GetColor3d("SlateGray").GetData());
  renWin->SetSize(640, 480);
  renWin->SetWindowName("ColoredSphere");

  renWin->Render();

  // interact with data
  iren->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt¶

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(ColoredSphere)

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

if (NOT VTK_FOUND)
  message(FATAL_ERROR "ColoredSphere: 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(ColoredSphere MACOSX_BUNDLE ColoredSphere.cxx )
  target_link_libraries(ColoredSphere PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS ColoredSphere
  MODULES ${VTK_LIBRARIES}
)

Download and Build ColoredSphere¶

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

cd ColoredSphere/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:

./ColoredSphere

WINDOWS USERS

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