[vtkusers] How to get the framebuffer

[Mathieu Westphal]

Hi,

It should work then.

Take a look into :
VTK/Rendering/OpenGL2/Testing/Cxx/TestRenderToImage.cxx
VTK/Rendering/Core/vtkWindowToImageFilter.cxx

Both are doing exactly what you are trying to do.
The first one (the test) may be very useful to you.

Best regards,

Mathieu Westphal

On Wed, Jul 25, 2018 at 4:20 PM, ling Hai <qyaoza at gmail.com> wrote:

> Hi Mathieu,
> Thank you for the response, I am already calling renderWindow->Render(). I
> tried reading the front, back, left and right buffers but am still unable
> to get any data from the call. If it helps, I am not using shaders, color
> points, or opacity the blending mode is composite, it is rendered by the
> gpu.
>
> Linghai
>
> On Wed, Jul 25, 2018 at 3:52 AM, Mathieu Westphal <
> mathieu.westphal at kitware.com> wrote:
>
>> Hi LingHai
>>
>> Make sure you have rendered into the renderWindow first.
>> (renderWindow->Render())
>> And try to read from the front and the back buffer.
>>
>> Best regards,
>>
>> Mathieu Westphal
>>
>> On Tue, Jul 24, 2018 at 7:57 PM, ling Hai <qyaoza at gmail.com> wrote:
>>
>>> Hi,
>>> I am new to vtk and I am trying to get the front framebuffer from the
>>> renderwindow like this:
>>> int * dim = renderWindow->GetSize();
>>> unsigned char* pixels = renderWindow->GetPixelData(0,0
>>> ,dim[0]-1,dim[1]-1,true);
>>>
>>> but in pixels there is only a null value. I am using this on a 3d render
>>> if that makes a difference the above segment of code called after rendering
>>> the volume. What am I missing? Any help is appreciated thanks.
>>> Linghai
>>>
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