ClipFrustum
vtk-examples/Cxx/Meshes/ClipFrustum
Description¶
The example uses vtkClipPolyData to clip a model with a vtkCamera's view frustum. The frustum is displayed using vtkFrustumSource.
The example proceeds as follow:
- Read a vtkPolyData. The example can read any of the supported polydata readers.
- Generates a view of the model.
- Recovers the view frustum of the current vtkCamera.
- Creates an implicit function using vtkPlanes::SetFrustumPlanes.
- Passes the vtkPlanes to vtkFrustumSource.
- Passes the vtkPlanes to vtkClipPolyData as the ClipFunction.
- Tells vtkClipPolyData to generate vtkPolyData for inside and outside.
- Presents the frustum, and clipped models. The inside model is red and the outside model is gold.
Bug
The first attempt to write the example used vtkClipConvexPolyData, but that filter has bugs and only works with one plane.
Question
If you have a question about this example, please use the VTK Discourse Forum
Code¶
ClipFrustum.cxx
#include <vtkClipPolyData.h>
#include <vtkFrustumSource.h>
#include <vtkNamedColors.h>
#include <vtkPlanes.h>
#include <vtkPolyDataNormals.h>
#include <vtkBYUReader.h>
#include <vtkOBJReader.h>
#include <vtkPLYReader.h>
#include <vtkPolyDataReader.h>
#include <vtkSTLReader.h>
#include <vtkSphereSource.h>
#include <vtkXMLPolyDataReader.h>
#include <vtksys/SystemTools.hxx>
#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkMapper.h>
#include <vtkNew.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>
namespace {
vtkSmartPointer<vtkPolyData> ReadPolyData(const char* fileName);
void PositionCamera(vtkRenderer* renderer, double* viewUp,
double* position);
} // namespace
int main(int argc, char* argv[])
{
auto polyData = ReadPolyData(argc > 1 ? argv[1] : "");
vtkNew<vtkNamedColors> colors;
// a renderer and render window
vtkNew<vtkRenderer> renderer;
vtkNew<vtkRenderWindow> renderWindow;
renderWindow->AddRenderer(renderer);
// an interactor
vtkNew<vtkRenderWindowInteractor> renderWindowInteractor;
renderWindowInteractor->SetRenderWindow(renderWindow);
vtkNew<vtkPolyDataMapper> mapper;
mapper->SetInputData(polyData);
mapper->ScalarVisibilityOff();
vtkNew<vtkActor> actor;
actor->SetMapper(mapper);
actor->GetProperty()->SetDiffuseColor(
colors->GetColor3d("Crimson").GetData());
actor->GetProperty()->SetSpecular(.6);
actor->GetProperty()->SetSpecularPower(30);
renderer->AddActor(actor);
vtkNew<vtkPolyDataMapper> outMapper;
outMapper->SetInputData(polyData);
outMapper->ScalarVisibilityOff();
vtkNew<vtkActor> outActor;
outActor->SetMapper(outMapper);
outActor->GetProperty()->SetDiffuseColor(
colors->GetColor3d("Gold").GetData());
outActor->GetProperty()->SetSpecular(.6);
outActor->GetProperty()->SetSpecularPower(30);
// Position the camera so that we can see the frustum
double viewUp[3] = {0.0, 1.0, 0.0};
double position[3] = {1.0, 0.0, 0.0};
PositionCamera(renderer, viewUp, position);
renderer->GetActiveCamera()->Elevation(30);
renderer->GetActiveCamera()->SetViewAngle(10.0);
double planesArray[24];
renderer->GetActiveCamera()->GetFrustumPlanes(1.0, planesArray);
vtkNew<vtkPlanes> planes;
planes->SetFrustumPlanes(planesArray);
vtkNew<vtkFrustumSource> frustumSource;
frustumSource->ShowLinesOff();
frustumSource->SetPlanes(planes);
frustumSource->Update();
vtkNew<vtkPolyDataMapper> frustumMapper;
frustumMapper->SetInputConnection(frustumSource->GetOutputPort());
vtkNew<vtkActor> frustumActor;
frustumActor->SetMapper(frustumMapper);
frustumActor->GetProperty()->EdgeVisibilityOn();
frustumActor->GetProperty()->SetOpacity(.5);
frustumActor->GetProperty()->SetColor(colors->GetColor3d("Banana").GetData());
vtkNew<vtkClipPolyData> clip;
clip->SetInputData(polyData);
clip->SetClipFunction(planes);
clip->InsideOutOn();
clip->GenerateClippedOutputOn();
clip->Update();
mapper->SetInputConnection(clip->GetOutputPort());
outMapper->SetInputData(clip->GetClippedOutput());
renderer->SetBackground(colors->GetColor3d("Silver").GetData());
renderer->AddActor(frustumActor);
renderer->AddActor(outActor);
renderer->ResetCamera();
renderer->GetActiveCamera()->Azimuth(30);
renderer->GetActiveCamera()->Elevation(30);
renderer->GetActiveCamera()->Dolly(1.5);
renderer->ResetCameraClippingRange();
renderWindow->SetSize(640, 480);
renderWindow->SetWindowName("ClipFrustum");
renderWindow->Render();
// begin mouse interaction
renderWindowInteractor->Start();
return EXIT_SUCCESS;
}
// Snippets
namespace {
vtkSmartPointer<vtkPolyData> ReadPolyData(const char* fileName)
{
vtkSmartPointer<vtkPolyData> polyData;
std::string extension =
vtksys::SystemTools::GetFilenameExtension(std::string(fileName));
if (extension == ".ply")
{
vtkNew<vtkPLYReader> reader;
reader->SetFileName(fileName);
reader->Update();
polyData = reader->GetOutput();
}
else if (extension == ".vtp")
{
vtkNew<vtkXMLPolyDataReader> reader;
reader->SetFileName(fileName);
reader->Update();
polyData = reader->GetOutput();
}
else if (extension == ".obj")
{
vtkNew<vtkOBJReader> reader;
reader->SetFileName(fileName);
reader->Update();
polyData = reader->GetOutput();
}
else if (extension == ".stl")
{
vtkNew<vtkSTLReader> reader;
reader->SetFileName(fileName);
reader->Update();
polyData = reader->GetOutput();
}
else if (extension == ".vtk")
{
vtkNew<vtkPolyDataReader> reader;
reader->SetFileName(fileName);
reader->Update();
polyData = reader->GetOutput();
}
else if (extension == ".g")
{
vtkNew<vtkBYUReader> reader;
reader->SetGeometryFileName(fileName);
reader->Update();
polyData = reader->GetOutput();
}
else
{
vtkNew<vtkSphereSource> source;
source->Update();
polyData = source->GetOutput();
}
return polyData;
}
void PositionCamera(vtkRenderer* renderer, double* viewUp, double* position)
{
renderer->GetActiveCamera()->SetFocalPoint(0.0, 0.0, 0.0);
renderer->GetActiveCamera()->SetViewUp(viewUp);
renderer->GetActiveCamera()->SetPosition(position);
renderer->ResetCamera();
return;
}
} // namespace
CMakeLists.txt¶
cmake_minimum_required(VERSION 3.3 FATAL_ERROR)
project(ClipFrustum)
find_package(VTK COMPONENTS
vtkCommonColor
vtkCommonCore
vtkCommonDataModel
vtkFiltersCore
vtkFiltersSources
vtkIOGeometry
vtkIOLegacy
vtkIOPLY
vtkIOXML
vtkInteractionStyle
vtkRenderingContextOpenGL2
vtkRenderingCore
vtkRenderingFreeType
vtkRenderingGL2PSOpenGL2
vtkRenderingOpenGL2
QUIET
)
if (NOT VTK_FOUND)
message("Skipping ClipFrustum: ${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(ClipFrustum MACOSX_BUNDLE ClipFrustum.cxx )
target_link_libraries(ClipFrustum PRIVATE ${VTK_LIBRARIES})
else ()
# include all components
add_executable(ClipFrustum MACOSX_BUNDLE ClipFrustum.cxx )
target_link_libraries(ClipFrustum PRIVATE ${VTK_LIBRARIES})
# vtk_module_autoinit is needed
vtk_module_autoinit(
TARGETS ClipFrustum
MODULES ${VTK_LIBRARIES}
)
endif ()
Download and Build ClipFrustum¶
Click here to download ClipFrustum and its CMakeLists.txt file. Once the tarball ClipFrustum.tar has been downloaded and extracted,
cd ClipFrustum/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:
./ClipFrustum
WINDOWS USERS
Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.