ReverseAccess
Repository source: ReverseAccess
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Code¶
ReverseAccess.cxx
// This example demonstrates how to access the source object
// (e.g. vtkSphereSource) from the actor reversely.
// Some standard vtk headers.
#include <vtkActor.h>
#include <vtkCamera.h>
#include <vtkMath.h>
#include <vtkNamedColors.h>
#include <vtkNew.h>
#include <vtkPolyDataMapper.h>
#include <vtkProperty.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkSmartPointer.h>
#include <vtkSphereSource.h>
// Additionally needed vtk header for this example.
#include <vtkAlgorithmOutput.h>
int main(int, char*[])
{
vtkNew<vtkNamedColors> colors;
// Source
vtkNew<vtkSphereSource> sphere;
sphere->SetRadius(0.5);
// Mapper
vtkNew<vtkPolyDataMapper> sphereMapper;
sphereMapper->SetInputConnection(sphere->GetOutputPort());
// Actor
vtkNew<vtkActor> sphereActor;
sphereActor->SetMapper(sphereMapper);
sphereActor->GetProperty()->SetColor(
colors->GetColor3d("MistyRose").GetData());
// Renderer
vtkNew<vtkRenderer> ren1;
ren1->SetBackground(colors->GetColor3d("CadetBlue").GetData());
vtkNew<vtkRenderWindow> renWin;
renWin->AddRenderer(ren1);
renWin->SetSize(300, 300);
renWin->SetWindowName("ReverseAccess");
// Add actor to the renderer.
ren1->AddActor(sphereActor);
/*
Now we retrieve the source object from vtkActor reversely, meaning we
don't use the sphere source object we instantiated above directly,
instead we retrieve a reference to the sphere source through the actor.
An advantage of this concept might be that we don't need to maintain
the source object anymore in a more complex application.
To demonstrate that we can modify properties of the sphere source
through this reference beside changing some properties of the actor
(in this example we change actor's x-position), we change the radius
of the sphere source as well.
The next two lines are the core lines for reverse access.
*/
vtkSmartPointer<vtkAlgorithm> algorithm =
sphereActor->GetMapper()->GetInputConnection(0, 0)->GetProducer();
auto srcReference = dynamic_cast<vtkSphereSource*>(algorithm.GetPointer());
float origRadius = srcReference->GetRadius();
for (int i = 0; i < 360; ++i)
{
// Change radius of the sphere source.
srcReference->SetRadius(origRadius *
(1 + sin((float)i / 180.0 * vtkMath::Pi())));
// Change the x-position of the actor.
sphereActor->SetPosition(sin((float)i / 45.0 * vtkMath::Pi()) * 0.5, 0, 0);
renWin->Render();
}
// Thanks to the usage of vtkNew there is no explicit need
// to free any objects at this point.
return EXIT_SUCCESS;
}
CMakeLists.txt¶
cmake_minimum_required(VERSION 3.12 FATAL_ERROR)
project(ReverseAccess)
find_package(VTK COMPONENTS
CommonColor
CommonCore
CommonExecutionModel
FiltersSources
InteractionStyle
RenderingContextOpenGL2
RenderingCore
RenderingFreeType
RenderingGL2PSOpenGL2
RenderingOpenGL2
)
if (NOT VTK_FOUND)
message(FATAL_ERROR "ReverseAccess: 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(ReverseAccess MACOSX_BUNDLE ReverseAccess.cxx )
target_link_libraries(ReverseAccess PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
TARGETS ReverseAccess
MODULES ${VTK_LIBRARIES}
)
Download and Build ReverseAccess¶
Click here to download ReverseAccess and its CMakeLists.txt file. Once the tarball ReverseAccess.tar has been downloaded and extracted,
cd ReverseAccess/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:
./ReverseAccess
WINDOWS USERS
Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.