cone6.cxx

a very goog book

/*=========================================================================

  Program:   Visualization Toolkit
  Module:    $RCSfile: Cone6.cxx,v $
  Language:  C++
  Date:      $Date: 2002/11/14 21:00:05 $
  Version:   $Revision: 1.1 $

  Copyright (c) 1993-2002 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 introduces 3D widgets. 3D widgets take advantage of the
// event/observer design pattern introduced previously. They typically
// have a particular representation in the scene which can be interactively
// selected and manipulated using the mouse and keyboard. As the widgets
// are manipulated, they in turn invoke events such as StartInteractionEvent,
// InteractionEvent, and EndInteractionEvent which can be used to manipulate
// the scene that the widget is embedded in. 3D widgets work in the context
// of the event loop which was set up in the previous example.
//
// Note: there are more 3D widget examples in VTK/Examples/GUI/.
//

// First include the required header files for the VTK classes we are using.
#include "vtkConeSource.h"
#include "vtkPolyDataMapper.h"
#include "vtkRenderWindow.h"
#include "vtkRenderWindowInteractor.h"
#include "vtkCamera.h"
#include "vtkActor.h"
#include "vtkRenderer.h"
#include "vtkCommand.h"
#include "vtkBoxWidget.h"
#include "vtkTransform.h"
#include "vtkInteractorStyleTrackballCamera.h"

//
// Similar to Cone2.cxx, we define a callback for interaction.
// 
class vtkMyCallback : public vtkCommand
{
public:
  static vtkMyCallback *New() 
    { return new vtkMyCallback; }
  void Delete()
    { delete this; }
  virtual void Execute(vtkObject *caller, unsigned long, void*)
    {
      vtkTransform *t = vtkTransform::New();
      vtkBoxWidget *widget = reinterpret_cast<vtkBoxWidget*>(caller);
      widget->GetTransform(t);
      widget->GetProp3D()->SetUserTransform(t);
    }
};

int main( int argc, char *argv[] )
{
  // 
  // Next we create an instance of vtkConeSource and set some of its
  // properties. The instance of vtkConeSource "cone" is part of a
  // visualization pipeline (it is a source process object); it produces data
  // (output type is vtkPolyData) which other filters may process.
  //
  vtkConeSource *cone = vtkConeSource::New();
  cone->SetHeight( 3.0 );
  cone->SetRadius( 1.0 );
  cone->SetResolution( 10 );
  
  // 
  // In this example we terminate the pipeline with a mapper process object.
  // (Intermediate filters such as vtkShrinkPolyData could be inserted in
  // between the source and the mapper.)  We create an instance of
  // vtkPolyDataMapper to map the polygonal data into graphics primitives. We
  // connect the output of the cone souece to the input of this mapper.
  //
  vtkPolyDataMapper *coneMapper = vtkPolyDataMapper::New();
  coneMapper->SetInput( cone->GetOutput() );

  // 
  // Create an actor to represent the cone. The actor orchestrates rendering
  // of the mapper's graphics primitives. An actor also refers to properties
  // via a vtkProperty instance, and includes an internal transformation
  // matrix. We set this actor's mapper to be coneMapper which we created
  // above.
  //
  vtkActor *coneActor = vtkActor::New();
  coneActor->SetMapper( coneMapper );

  //
  // Create the Renderer and assign actors to it. A renderer is like a
  // viewport. It is part or all of a window on the screen and it is
  // responsible for drawing the actors it has.  We also set the background
  // color here.
  //
  vtkRenderer *ren1= vtkRenderer::New();
  ren1->AddActor( coneActor );
  ren1->SetBackground( 0.1, 0.2, 0.4 );

  //
  // Finally we create the render window which will show up on the screen.
  // We put our renderer into the render window using AddRenderer. We also
  // set the size to be 300 pixels by 300.
  //
  vtkRenderWindow *renWin = vtkRenderWindow::New();
  renWin->AddRenderer( ren1 );
  renWin->SetSize( 300, 300 );

  // 
  // The vtkRenderWindowInteractor class watches for events (e.g., keypress,
  // mouse) in the vtkRenderWindow. These events are translated into
  // event invocations that VTK understands (see VTK/Common/vtkCommand.h
  // for all events that VTK processes). Then observers of these VTK
  // events can process them as appropriate.
  vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
  iren->SetRenderWindow(renWin);

  //
  // By default the vtkRenderWindowInteractor instantiates an instance
  // of vtkInteractorStyle. vtkInteractorStyle translates a set of events
  // it observes into operations on the camera, actors, and/or properties
  // in the vtkRenderWindow associated with the vtkRenderWinodwInteractor. 
  // Here we specify a particular interactor style.
  vtkInteractorStyleTrackballCamera *style = 
    vtkInteractorStyleTrackballCamera::New();
  iren->SetInteractorStyle(style);

  //
  // Here we use a vtkBoxWidget to transform the underlying coneActor (by
  // manipulating its transformation matrix). Many other types of widgets
  // are available for use, see the documentation for more details.
  //
  // The SetInteractor method is how 3D widgets are associated with the render
  // window interactor. Internally, SetInteractor sets up a bunch of callbacks
  // using the Command/Observer mechanism (AddObserver()). The place factor 
  // controls the initial size of the widget with respect to the bounding box
  // of the input to the widget.
  vtkBoxWidget *boxWidget = vtkBoxWidget::New();
  boxWidget->SetInteractor(iren);
  boxWidget->SetPlaceFactor(1.25);

  //
  // Place the interactor initially. The input to a 3D widget is used to 
  // initially position and scale the widget. The EndInteractionEvent is
  // observed which invokes the SelectPolygons callback.
  //
  boxWidget->SetProp3D(coneActor);
  boxWidget->PlaceWidget();
  vtkMyCallback *callback = vtkMyCallback::New();
  boxWidget->AddObserver(vtkCommand::InteractionEvent, callback);

  //
  // Normally the user presses the "i" key to bring a 3D widget to life. Here
  // we will manually enable it so it appears with the cone. 
  //
  boxWidget->On();

  //
  // Start the event loop.
  //
  iren->Initialize();
  iren->Start();
  
  //
  // Free up any objects we created. All instances in VTK are deleted by
  // using the Delete() method.
  //
  cone->Delete();
  coneMapper->Delete();
  coneActor->Delete();
  callback->Delete();
  boxWidget->Delete();
  ren1->Delete();
  renWin->Delete();
  iren->Delete();
  style->Delete();

  return 0;
}