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/*=========================================================================
Program: Visualization Toolkit
Module: Cone2.cxx
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
//
// This example shows how to add an observer to a C++ program. It extends
// the Step1/Cxx/Cone.cxx C++ example (see that example for information on
// the basic setup).
//
// VTK uses a command/observer design pattern. That is, observers watch for
// particular events that any vtkObject (or subclass) may invoke on
// itself. For example, the vtkRenderer invokes a "StartEvent" as it begins
// to render. Here we add an observer that invokes a command when this event
// is observed.
//
// first include the required header files for the vtk classes we are using
#include "vtkActor.h"
#include "vtkCamera.h"
#include "vtkCommand.h"
#include "vtkConeSource.h"
#include "vtkPolyDataMapper.h"
#include "vtkRenderWindow.h"
#include "vtkRenderer.h"
// Callback for the interaction
class vtkMyCallback : public vtkCommand
{
public:
static vtkMyCallback* New() { return new vtkMyCallback; }
void Execute(vtkObject* caller, unsigned long, void*) override
{
vtkRenderer* renderer = reinterpret_cast<vtkRenderer*>(caller);
cout << renderer->GetActiveCamera()->GetPosition()[0] << " "
<< renderer->GetActiveCamera()->GetPosition()[1] << " "
<< renderer->GetActiveCamera()->GetPosition()[2] << "\n";
}
};
int main()
{
//
// The pipeline creation is documented in Step1
//
vtkConeSource* cone = vtkConeSource::New();
cone->SetHeight(3.0);
cone->SetRadius(1.0);
cone->SetResolution(10);
vtkPolyDataMapper* coneMapper = vtkPolyDataMapper::New();
coneMapper->SetInputConnection(cone->GetOutputPort());
vtkActor* coneActor = vtkActor::New();
coneActor->SetMapper(coneMapper);
vtkRenderer* ren1 = vtkRenderer::New();
ren1->AddActor(coneActor);
ren1->SetBackground(0.1, 0.2, 0.4);
ren1->ResetCamera();
vtkRenderWindow* renWin = vtkRenderWindow::New();
renWin->AddRenderer(ren1);
renWin->SetSize(300, 300);
// Here is where we setup the observer, we do a new and ren1 will
// eventually free the observer
vtkMyCallback* mo1 = vtkMyCallback::New();
ren1->AddObserver(vtkCommand::StartEvent, mo1);
mo1->Delete();
//
// now we loop over 360 degrees and render the cone each time
//
int i;
for (i = 0; i < 360; ++i)
{
// render the image
renWin->Render();
// rotate the active camera by one degree
ren1->GetActiveCamera()->Azimuth(1);
}
//
// Free up any objects we created
//
cone->Delete();
coneMapper->Delete();
coneActor->Delete();
ren1->Delete();
renWin->Delete();
return 0;
}
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