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

Thu Aug 6 16:52:45 EDT 2015

On Thu, Aug 6, 2015 at 4:43 PM, Totte Karlsson <totte at dunescientific.com>
wrote:

>
>
> 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.
>

I guess I don't see the problem here. You have a reference to the actor
here, and the actor has the orientation. Did you try this approach out and
it didn't work? vtkActor::SetOrientation(0, 0, 0) will reset the rotation
for you.

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

I don't know of a quick and easy way to get the incremental rotation you
are looking for, hence my suggestion.

Cory

>
>
> tk
>
> 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>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>
>>> 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.
>
>
> --
> ------------------------------
> <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.
>
>
>
> _______________________________________________
> Powered by www.kitware.com
>
> Visit other Kitware open-source projects at
> http://www.kitware.com/opensource/opensource.html
>
> Please keep messages on-topic and check the VTK FAQ at:
> http://www.vtk.org/Wiki/VTK_FAQ
>
> Search the list archives at: http://markmail.org/search/?q=vtkusers
>
> Follow this link to subscribe/unsubscribe:
> http://public.kitware.com/mailman/listinfo/vtkusers
>
>

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