[vtkusers] Using a boxwidgets transform to rotate a non-vtk 3D model?

Totte Karlsson totte at dunescientific.com
Thu Aug 6 16:43:02 EDT 2015 


On 8/6/2015 1:35 PM, Cory Quammen wrote:
> Does your "anActor" have the ability to reset the rotation? If so, 
> then you can just reset it and then apply the accumulated rotation as 
> you are doing, e.g.
>
> anActor->SetOrientation(0, 0, 0);
> anActor->RotateWXYZ(wxyz[0], wxyz[1], wxyz[2], wxyz[3]);
>
> This would be nice because you wouldn't need to store the last 
> rotation to undo it.
>
The anActor is just a regular vtkActor (a cone) for now.

The 'reset' is effectively the line of code:
  anActor->RotateWXYZ(-lastAngle, lastWXYZ[1], lastWXYZ[2], lastWXYZ[3]);

One would need to store this input somewhere in order to do this, as it 
would be different each time.

What I'm looking for is instead to perform incremental rotations, 
avoiding the "transforming back", i.e. (reset) part.

tk

> On Thu, Aug 6, 2015 at 4:26 PM, Totte Karlsson 
> <totte at dunescientific.com <mailto:totte at dunescientific.com>> wrote:
>
>     Hello Cory,
>     I was able to use your suggestion and got some code to work, as
>     follows:
>
>         virtual void Execute(vtkObject *caller, unsigned long, void*)
>         {
>             static int callCount = 0;
>             static double lastAngle = 0;
>             static double lastVec[3] = {0,0,0};
>             vtkSmartPointer<vtkTransform> t =
>     vtkSmartPointer<vtkTransform>::New();
>             static vtkSmartPointer<vtkTransform> lastTransform =
>     vtkSmartPointer<vtkTransform>::New();
>             vtkBoxWidget *widget =
>     reinterpret_cast<vtkBoxWidget*>(caller);
>             widget->GetTransform(t);
>
>             double* wxyz = t->GetOrientationWXYZ();
>             double* lastWXYZ = lastTransform->GetOrientationWXYZ();
>
>             if(anActor)
>             {
>                 cout<<"CallCount: "<<callCount<<"Current Angle
>     "<<wxyz[0]<<" Effective angle:"<< wxyz[0] - lastAngle<<endl;
>
>                 //Transform 'back'
>                 anActor->RotateWXYZ(-lastAngle, lastWXYZ[1],
>     lastWXYZ[2], lastWXYZ[3]);
>                 anActor->RotateWXYZ(wxyz[0], wxyz[1], wxyz[2], wxyz[3]);
>             }
>
>             //Save transform data
>             lastAngle = wxyz[0] ;
>             lastVec[0] =wxyz[1];
>             lastVec[1] =wxyz[2];
>             lastVec[2] =wxyz[3];
>
>             lastTransform = t;
>             callCount++;
>         }
>
>     In the above code, two transformations of the actor are done, in
>     order to follow the orientation of the widget. 1) to rotate the
>     actor to its initial position, and 2), applying current
>     transformation.
>
>     Although the above code works, is there a way to get the
>     'incremental' transform somehow? I'm a novice about these things
>     so sorry if asking something obvious...
>
>     tk
>
>
>     On 8/6/2015 7:40 AM, Cory Quammen wrote:
>>     TK,
>>
>>     You can get the orientation in angle-axis representation with
>>
>>     double wxyz[4];
>>     t->GetOrientationWXYZ(wxyz);
>>
>>     From the docs [1]:
>>
>>     The angle (w) is in degrees and the axis (xyz) is a unit vector.
>>
>>     You should be able to apply this rotation to your molecule
>>     model's RotateAboutVector function.
>>
>>     HTH,
>>     Cory
>>
>>     [1]
>>     http://www.vtk.org/doc/nightly/html/classvtkTransform.html#aa8244cbab95a2dbb20e94af6e7f16b7f
>>
>>
>>     On Wed, Aug 5, 2015 at 8:54 PM, Totte Karlsson
>>     <totte at dunescientific.com <mailto:totte at dunescientific.com>> wrote:
>>
>>         Hello,
>>         I'm using vtk to visualize 3D models of molecules.
>>         The actual molecular model is decoupled from vtk code, and
>>         visualization is implemented using a model-view kind of design.
>>
>>         Currently I have the following challenge. If a user wants to
>>         manipulate the absolute orientation of the molecule, it is
>>         done by manipulating the underlying model using rotation
>>         functions, like RotateX, RotateY, RotateAboutVector, and
>>         translation functions TranslateX, Y etc.
>>
>>         For now 3D rotations are simply done using two scrollbars,
>>         one horizontal and one vertical, causing the underlying model
>>         being rotated about the vtk viewUP vector and the vtk
>>         cameraPlane normal respectively.  This works fine, but is not
>>         so intuitive for the user.
>>
>>         Instead I believe allowing interaction with something like a
>>         box widget that encapsulates the molecule view, (with
>>         disabled handles), would be better.
>>
>>         The challenge is how to figure out how to capture the
>>         boxwidgets orientation in a callback, and using this
>>         information in order to manipulate the underlying molecular
>>         model.
>>
>>         For example, a boxwidget callback (from boxwidget example at
>>         http://www.vtk.org/Wiki/VTK/Examples/Cxx/Widgets/BoxWidget):
>>
>>         class vtkMyCallback : public vtkCommand
>>         {
>>             public:
>>                 static vtkMyCallback *New()       {         return
>>         new vtkMyCallback;    }
>>
>>             virtual void Execute(vtkObject *caller, unsigned long, void*)
>>             {
>>                 vtkSmartPointer<vtkTransform> t =
>>         vtkSmartPointer<vtkTransform>::New();
>>                 vtkBoxWidget *widget =
>>         reinterpret_cast<vtkBoxWidget*>(caller);
>>                 widget->GetTransform(t);
>>
>>                 double* angles?? = t->GetOrientation();
>>                 if(aMoleculeModel)
>>                 {
>>                     //Use some secret(!) code to manipulate
>>         orientation of a molecule to 'rotate' it together with the
>>         boxWidget
>>                     aMoleculeModel->RotateZ(??);
>>                     aMoleculeModel->RotateY(??);
>>                     aMoleculeModel->RotateZ(??);
>>                 }
>>             }
>>             Molecule* aMoleculeModel;
>>
>>         Anyone seeing how to do this or have some pointers?
>>
>>         Cheers,
>>         tk
>>
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>>
>>
>>     -- 
>>     Cory Quammen
>>     R&D Engineer
>>     Kitware, Inc.
>
>     -- 
>     ------------------------------------------------------------------------
>     <http://www.dunescientific.com/> 				
>     Totte Karlsson: totte at dunescientific.com
>     <mailto:totte at dunescientific.com> or (425) 780-9648
>     <tel:%20425%20%20780-9648>
>     http://www.dunescientific.com/
>     © 2015 Dune Scientific, LLC. All rights reserved.
>
>
>
>
>
>
> -- 
> Cory Quammen
> R&D Engineer
> Kitware, Inc.

-- 
------------------------------------------------------------------------
<http://www.dunescientific.com/> 				
Totte Karlsson: totte at dunescientific.com 
<mailto:totte at dunescientific.com> or (425) 780-9648 
<tel:%20425%20%20780-9648>
http://www.dunescientific.com/
© 2015 Dune Scientific, LLC. All rights reserved.



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