[vtkusers] RE: Multi cameras in a render window

[Aroosha Laghaee]

Hi Ashley,

Do you mean that the actors only move in one renderer and not the 
other? I am not quite sure but try and put the camera and renderer 
functions before you initialze and start the interactor to see if that 
makes a difference.

vtkCamera *cam1 = ren1->GetActiveCamera();
vtkCamera *cam2 = ren2->GetActiveCamera();

ren1->ResetCamera();
renWin->Render();

iren->Initialize();
iren->Start();

However, I suspect that this is happening because you are not holding 
on to the renderers and render windows that you are creating (i.e. you 
are creating new instances at every function call and then deleting 
them at the end when the function exits) and so you will loose whatever 
change you make after the function returns.

In my code I have created my RenderWindow as a static class member to 
ensure that things do not happen in different copies of RenderWindows 
which get lost along the way.

So I have something like this:

class X
{
    //other functions
    static void Render();
    static void SetRenderWindow(vtkRenderWindow&);
    static vtkRenderWindow& GetRenderWindow();

private:
    //other members
    static vtkRenderWindow* m_RenWin;
};

So now all objects of type X are using the same instance of 
vtkRenderWindow and regardless of which one of them makes a change it 
will be updated and reflected correctly for all objects of type X.

Please check with the rest of the group as well since I am not an 
expert in any way and maybe talking absolute nonesense.

I hope this is of some help,
                        Aroosha

> Hey Aroosha,
>
> Sorry to bother you again.
>
> I tried to apply the concept to my implementation. It works perfectly 
> fine. However, when I interact with the actors, the actors move 
> individually.
> Do you happen to know how to implement the camera function so that 
> both actors in separate renderer will move together? Like 
> synchronizing the cameras?
> I tried looking through vtkCamera and vtkCameraInterpolator but it 
> was no avail.
>
> Hope you can advice. Thanks for your help! =)
>
> Regards,
> Ashley
> PS:  Attached to this mail is part of my codes.
>
>
>
> From: Aroosha Laghaee
> Sent: Wed 12-Apr-06 2:12 AM
> To: tany0029 at ntu.edu.sg
> Cc: vtkusers at vtk.org
> Subject: Re: Multi cameras in a render window
>
>
> Hello Ashley,
>
> My understanding of how this can be done is as follows:
>
> 1)You need to create 3 renderers
> 2)add your objects to all of these renderers
> 2)specify the location of each renderer's camera
> 4)add all of these renderers to your render window
>
> In this way you can have multiple view points of your objects in one
> window. I enclose the very good example which comes with vtk that shows
> you how to do this.
>
> I hope this helps,
>               Aroosha
>
> /*=========================================================================
>
>    Program:   Visualization Toolkit
>    Module:    $RCSfile: Cone3.cxx,v $
>    Language:  C++
>    Date:      $Date: 2002/11/15 17:53:45 $
>    Version:   $Revision: 1.2 $
>
>    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 demonstrates how to use multiple renderers within a
> // render window. It is a variation of the Cone.cxx example. Please
> // refer to that example for additional documentation.
> //
>
> // First include the required header files for the VTK classes we are using.
> #include "vtkConeSource.h"
> #include "vtkPolyDataMapper.h"
> #include "vtkRenderWindow.h"
> #include "vtkCamera.h"
> #include "vtkActor.h"
> #include "vtkRenderer.h"
>
> 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 two renderers and assign actors to them. A renderer renders into
>    // a viewport within the vtkRenderWindow. 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. In this example we are adding the same
>    // actor to two different renderers; it is okay to add different actors to
>    // different renderers as well.
>    //
>    vtkRenderer *ren1= vtkRenderer::New();
>    ren1->AddActor( coneActor );
>    ren1->SetBackground( 0.1, 0.2, 0.4 );
>    ren1->SetViewport(0.0, 0.0, 0.5, 1.0);
>
>    vtkRenderer *ren2= vtkRenderer::New();
>    ren2->AddActor( coneActor );
>    ren2->SetBackground( 0.2, 0.3, 0.5 );
>    ren2->SetViewport(0.5, 0.0, 1.0, 1.0);
>
>    //
>    // 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->AddRenderer( ren2 );
>    renWin->SetSize( 600, 300 );
>
>    //
>    // Make one view 90 degrees from other.
>    //
>    ren1->GetActiveCamera()->Azimuth(90);
>
>    //
>    // Now we loop over 360 degreeees 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 );
>      ren2->GetActiveCamera()->Azimuth( 1 );
>      }
>
>    //
>    // Free up any objects we created. All instances in VTK are deleted by
>    // using the Delete() method.
>    //
>    cone->Delete();
>    coneMapper->Delete();
>    coneActor->Delete();
>    ren1->Delete();
>    ren2->Delete();
>    renWin->Delete();
>
>    return 0;
> }
>
> Hi all,
>
> I would like to ask is it possible to have multi cameras in a render window
> viewing different angle of an object? For e.g. with one camera, i'll have
> the view of a plane in the window. Lets say i have 3 camera, i'll have the
> view of the plane being folded into threes (time wall).
>
> Thanks for the help in advance!!
> --
> View this message in context:
> http://www.nabble.com/Multi-cameras-in-a-render-window-t1409612.html#a3796403
> Sent from the VTK - Users forum at Nabble.com.
>