Hi, I’m trying to use a callback function for starting an action when a key(keyboard) is pressed. For doing this I’m implementing the “KeyPressObserver” example. My target is to increase the sphere radius when I click on “Right” arrow. This is the code
#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkSmartPointer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkPolyData.h>
#include <vtkSphereSource.h>
#include <vtkCallbackCommand.h>
#include <vtkCommand.h>
#include <vtkInteractorStyleTrackballCamera.h>
void KeypressCallbackFunction(
vtkObject* caller,
long unsigned int eventId,
void* clientData,
void* callData);
std::string key = "";
int main(int, char* [])
{
// Create a sphere
vtkSmartPointer<vtkSphereSource> sphereSource =
vtkSmartPointer<vtkSphereSource>::New();
sphereSource->SetCenter(0.0, 0.0, 0.0);
sphereSource->SetRadius(5.0);
sphereSource->Update();
vtkSmartPointer<vtkPolyDataMapper> mapper =
vtkSmartPointer<vtkPolyDataMapper>::New();
mapper->SetInputConnection(sphereSource->GetOutputPort());
// Create an actor
vtkSmartPointer<vtkActor> actor =
vtkSmartPointer<vtkActor>::New();
actor->SetMapper(mapper);
// A renderer and render window
vtkSmartPointer<vtkRenderer> renderer =
vtkSmartPointer<vtkRenderer>::New();
vtkSmartPointer<vtkRenderWindow> renderWindow =
vtkSmartPointer<vtkRenderWindow>::New();
renderWindow->AddRenderer(renderer);
// An interactor
vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor =
vtkSmartPointer<vtkRenderWindowInteractor>::New();
renderWindowInteractor->SetRenderWindow(renderWindow);
vtkSmartPointer<vtkCallbackCommand> keypressCallback =
vtkSmartPointer<vtkCallbackCommand>::New();
keypressCallback->SetCallback(KeypressCallbackFunction);
renderWindowInteractor->AddObserver(vtkCommand::KeyPressEvent, keypressCallback);
keypressCallback->SetClientData(sphereSource);
//key = renderWindowInteractor->GetKeySym();
renderer->InteractiveOn();
renderer->AddActor(actor);
renderWindowInteractor->Initialize();
renderer->SetBackground(1, 1, 1); // Background color white
renderWindow->Render();
renderWindowInteractor->Start();
return EXIT_SUCCESS;
}
void KeypressCallbackFunction(vtkObject* caller, long unsigned int
vtkNotUsed(eventId), void* clientData, void* callData)
{
std::cout << "Keypress callback" << std::endl;
vtkRenderWindowInteractor* iren =
static_cast<vtkRenderWindowInteractor*>(caller);
std::cout << "Pressed: " << iren->GetKeySym() << std::endl;
key = iren->GetKeySym();
vtkSphereSource* sphere =
static_cast<vtkSphereSource*>(clientData);
if (key == "Right") {
std::cout << "TEST RIGHT" << std::endl;
sphere->SetRadius(10);
sphere->Modified();
sphere->Update();
}
}
The problem is that when I run this code, the action connected to the keypress is starting only after that I click the right arrow and after a click with the mouse. I would like to start the action only with the right arrow, not also with a second click.
What is the problem? I didn’t find anything online for solving this, please help.
Thanks in advance