[vtkusers] Getting back OpenGL Context after data display/visualization using VTK

[Aashish Chaudhary]

On Thu, Mar 8, 2012 at 1:33 PM, Rudra Poudel <emailrudra at yahoo.com> wrote:

> Hi Aashish,
>
> Exactly, I need to set my application's OpenGL context to current between
> step 2 and 3.
> But as I have created OpenGL context with GLUT, I could not get/set using
> GLUT.
>

I don't remember glut that much now, but if you are using freeglut, you can
probably find the code where it is making context specific calls, and you
can probably add an API for your use case?


> And I dont like to use X window (I am currently on Ubuntu 11.10) as much
> as possible for platform independent sake.
>

Sure, I will look at the glut code

>
> Now please tell me how to do that? OR what is the best possible solution
> for above problem?
>
> Many thanks,
> Rudra
>
>   ------------------------------
> *From:* Aashish Chaudhary <aashish.chaudhary at kitware.com>
> *To:* Rudra Poudel <emailrudra at yahoo.com>
> *Cc:* "vtkusers at vtk.org" <vtkusers at vtk.org>
> *Sent:* Thursday, March 8, 2012 6:21 PM
>
> *Subject:* Re: [vtkusers] Getting back OpenGL Context after data
> display/visualization using VTK
>
> On Thu, Mar 8, 2012 at 1:08 PM, Rudra Poudel <emailrudra at yahoo.com> wrote:
>
> Hi Aashish,
>
> Thanks, just want to make sure I understood what you mean,
>
> My program LOOP {
> Step 1- I have FBO for main logic processing-  this step working fine
> Step 2- I want to use VTK for my results visualization only, then close
> all visualization windows
> Step 3- Again would like to work with my FBO here- BUMP- ERROR- FBO is
> invalid due to STEP 2
> }
>
> Now my questions again,
> 1. Aashish you mean- if I will do/call Step 2 then I could not make FBO
> work in Step 3? There must be some solution, isn't? The reason I am asking
> this question is I dont like to write my own code for visualization
> (re-inventing the wheel :( )
>
>
> I see..if I understood your correctly, then between step 2 and 3 you would
> need to make your context current
>
>
> 2. Can I build VTK without OpenGL support?
>
> Not sure what you mean here? If you want to use VTK for rendering you have
> to use OpenGL (you can use Mesa), if you are using VTK for reading file,
> data filtering etc, then
> you don't need to use OpenGL.
>
>
> Many thanks,
>
>
>
> Rudra
>
>    ------------------------------
> *From:* Aashish Chaudhary <aashish.chaudhary at kitware.com>
> *To:* Rudra Poudel <emailrudra at yahoo.com>
> *Cc:* "vtkusers at vtk.org" <vtkusers at vtk.org>
> *Sent:* Thursday, March 8, 2012 5:29 PM
> *Subject:* Re: [vtkusers] Getting back OpenGL Context after data
> display/visualization using VTK
>
> On Thu, Mar 8, 2012 at 11:36 AM, Rudra Poudel <emailrudra at yahoo.com>wrote:
>
> Hi All,
>
> - My application has Frame Buffer Object (FBO) for off-screen rendering (
> I used GLUT to init OpenGL Context- i.e. trick of invisible GLUT window)
> - When I display/visualize data using VTK function/class as obviously it
> take-over/create-new OpenGL context
> - Then I delete all VTK related functions/classes
> - Now when I tried to work with FBO it does-not-work/has-invalid-state.
>
>
> Since the FBO is created in different context you cannot use it in your
> glut context unless you created a shared FBO. It is bit tricky but doable.
>
>
> Questions,
> 1. What is the best/easiest solution to get back OpenGL Context after data
> display/visualization using VTK?
>
>
>
> 2. Might be building VTK without OpenGL support- however this looks
> impossible or ...?
>
>
> If you are using VTK for data filtering, sources then you can build your
> app where rendering is done only by your code obviously widget's wont work
> then.
>
>
>
>
> Thank you so much,
> Rudra
>
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>
>
> --
> | Aashish Chaudhary
> | R&D Engineer
> | Kitware Inc.
> | www.kitware.com
>
>
>
>
>
> --
> | Aashish Chaudhary
> | R&D Engineer
> | Kitware Inc.
> | www.kitware.com
>
>
>


-- 
| Aashish Chaudhary
| R&D Engineer
| Kitware Inc.
| www.kitware.com
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