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

[Cory Quammen]

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.

On Thu, Aug 6, 2015 at 4:26 PM, Totte Karlsson <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>
> 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>
> 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 or (425) 780-9648
> <%20425%20%20780-9648>
> http://www.dunescientific.com/
> © 2015 Dune Scientific, LLC. All rights reserved.
>
>
>


-- 
Cory Quammen
R&D Engineer
Kitware, Inc.
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