[vtkusers] Using vtkExternalOpenGLCamera

[Elaine Jiang]

Hi Sankhesh,

I've tried setting the camera and focal point parameters without using
SetProjectionMatrix() and SetModelViewTransformMatrix(), and I've also
tried just calling SetProjectionMatrix() and SetModelViewTransformMatrix()
by themselves. Neither approach seemed to have an effect on the scene. I
was looking through the documentation and was wondering if I need to use
the function vtkCamera::vtkSetUseExplicitProjectionTransformMatrix(bool) to
solve the problem?

Thanks,
Elaine

On Thu, Jul 20, 2017 at 11:12 AM, Sankhesh Jhaveri <
sankhesh.jhaveri at kitware.com> wrote:

> Hi,
>
> Could you please provide more details on how you’re trying to set the
> camera parameters?
> The way the external camera works is that it ignores the camera position
> and focal point parameters if the projection and model view matrices are
> set explicitly using vtkExternalOpenGLCamera::SetProjectionMatrix() and
> vtkExternalOpenGLCamera::SetModelViewTransformMatrix()
>
> Thanks,
> Sankhesh
> ​
>
> On Wed, Jul 19, 2017 at 9:59 AM elainejiang8 <elainejiang8 at gmail.com>
> wrote:
>
>> Hi everyone!
>>
>> I'm building a program that uses the externalVTKWidget to volume render an
>> object in an OpenGL context. Right now, I'm calling
>>
>> *ren->GetActiveCamera();
>> *
>>
>> (where ren is a vtkExternalOpenGLRenderWindow instance) in my render
>> function so I can control the position and focal point of the camera.
>> However, I'm unable to get the camera to actually have any effect on the
>> scene. The documentation for vtkExternalOpenGLCamera is rather slim, and I
>> can't find any similar examples, so I am a bit stuck on this issue.
>>
>> Does anyone have any insight into how I could approach this problem?
>> Thanks
>> in advance!
>>
>> Elaine
>>
>>
>>
>> --
>> View this message in context: http://vtk.1045678.n5.nabble.com/Using-
>> vtkExternalOpenGLCamera-tp5744015.html
>> Sent from the VTK - Users mailing list archive at Nabble.com.
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> --
> Sankhesh Jhaveri *Sr. Research & Development Engineer* | Kitware
> <http://www.kitware.com/> | (518) 881-4417
> ​
>
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