[vtkusers] How to get the framebuffer

ling Hai qyaoza at gmail.com
Wed Jul 25 10:20:13 EDT 2018

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


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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