<div dir="ltr">In current VTK I cannot see how GetPixelData can return null unless new returns null due to being out of memory. The code boils down to <div><br></div><div><div> unsigned char* ucdata = new unsigned char[width * height * 3];</div><div> vtkRecti rect(x_low, y_low, width, height);</div><div> this->ReadPixels(rect, front, GL_RGB, GL_UNSIGNED_BYTE, ucdata, right);</div><div> return ucdata;</div></div><div><br></div><div>So if the return value is nullptr then "new" failed. So check around maybe something else funny is going on.</div><div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Jul 25, 2018 at 10:24 AM, Mathieu Westphal <span dir="ltr"><<a href="mailto:mathieu.westphal@kitware.com" target="_blank">mathieu.westphal@kitware.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi,<div><br></div><div>It should work then.</div><div><br></div><div>Take a look into : </div><div>VTK/Rendering/OpenGL2/Testing/<wbr>Cxx/TestRenderToImage.cxx</div><div>VTK/Rendering/Core/<wbr>vtkWindowToImageFilter.cxx<br></div><div><br></div><div>Both are doing exactly what you are trying to do.</div><div>The first one (the test) may be very useful to you.</div><div><br></div><div>Best regards,</div></div><div class="gmail_extra"><br clear="all"><div><div class="m_-3959379645480281864gmail_signature" data-smartmail="gmail_signature"><div dir="ltr">Mathieu Westphal<br></div></div></div>
<br><div class="gmail_quote">On Wed, Jul 25, 2018 at 4:20 PM, ling Hai <span dir="ltr"><<a href="mailto:qyaoza@gmail.com" target="_blank">qyaoza@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div>Hi Mathieu,</div><div>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.</div><div><br></div><div>Linghai <br></div></div><div class="m_-3959379645480281864HOEnZb"><div class="m_-3959379645480281864h5"><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Jul 25, 2018 at 3:52 AM, Mathieu Westphal <span dir="ltr"><<a href="mailto:mathieu.westphal@kitware.com" target="_blank">mathieu.westphal@kitware.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi LingHai<div><br></div><div>Make sure you have rendered into the renderWindow first. (renderWindow->Render())</div><div>And try to read from the front and the back buffer.</div><div><br></div><div>Best regards,</div></div><div class="gmail_extra"><br clear="all"><div><div class="m_-3959379645480281864m_8833283803592622795m_-6689973853491295523gmail_signature" data-smartmail="gmail_signature"><div dir="ltr">Mathieu Westphal<br></div></div></div>
<br><div class="gmail_quote"><div><div class="m_-3959379645480281864m_8833283803592622795h5">On Tue, Jul 24, 2018 at 7:57 PM, ling Hai <span dir="ltr"><<a href="mailto:qyaoza@gmail.com" target="_blank">qyaoza@gmail.com</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="m_-3959379645480281864m_8833283803592622795h5"><div dir="ltr"><div>Hi,</div><div>I am new to vtk and I am trying to get the front framebuffer from the renderwindow like this:</div><div>int * dim = renderWindow->GetSize();<br>unsigned char* pixels = renderWindow->GetPixelData(0,0<wbr>,dim[0]-1,dim[1]-1,true);</div><div><br></div><div>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.</div><div>Linghai<br></div></div>
<br></div></div>______________________________<wbr>_________________<br>
Powered by <a href="http://www.kitware.com" rel="noreferrer" target="_blank">www.kitware.com</a><br>
<br>
Visit other Kitware open-source projects at <a href="http://www.kitware.com/opensource/opensource.html" rel="noreferrer" target="_blank">http://www.kitware.com/opensou<wbr>rce/opensource.html</a><br>
<br>
Please keep messages on-topic and check the VTK FAQ at: <a href="http://www.vtk.org/Wiki/VTK_FAQ" rel="noreferrer" target="_blank">http://www.vtk.org/Wiki/VTK_FA<wbr>Q</a><br>
<br>
Search the list archives at: <a href="http://markmail.org/search/?q=vtkusers" rel="noreferrer" target="_blank">http://markmail.org/search/?q=<wbr>vtkusers</a><br>
<br>
Follow this link to subscribe/unsubscribe:<br>
<a href="https://public.kitware.com/mailman/listinfo/vtkusers" rel="noreferrer" target="_blank">https://public.kitware.com/mai<wbr>lman/listinfo/vtkusers</a><br>
<br></blockquote></div><br></div>
</blockquote></div><br></div>
</div></div></blockquote></div><br></div>
<br>______________________________<wbr>_________________<br>
Powered by <a href="http://www.kitware.com" rel="noreferrer" target="_blank">www.kitware.com</a><br>
<br>
Visit other Kitware open-source projects at <a href="http://www.kitware.com/opensource/opensource.html" rel="noreferrer" target="_blank">http://www.kitware.com/<wbr>opensource/opensource.html</a><br>
<br>
Please keep messages on-topic and check the VTK FAQ at: <a href="http://www.vtk.org/Wiki/VTK_FAQ" rel="noreferrer" target="_blank">http://www.vtk.org/Wiki/VTK_<wbr>FAQ</a><br>
<br>
Search the list archives at: <a href="http://markmail.org/search/?q=vtkusers" rel="noreferrer" target="_blank">http://markmail.org/search/?q=<wbr>vtkusers</a><br>
<br>
Follow this link to subscribe/unsubscribe:<br>
<a href="https://public.kitware.com/mailman/listinfo/vtkusers" rel="noreferrer" target="_blank">https://public.kitware.com/<wbr>mailman/listinfo/vtkusers</a><br>
<br></blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div>Ken Martin PhD<div>Distinguished Engineer<br><span style="font-size:12.8px">Kitware Inc.</span><br></div><div>101 East Weaver Street<br>Carrboro, North Carolina<br>
27510 USA<br><br><div><span style="font-size:10pt;font-family:Tahoma,sans-serif">This communication,
including all attachments, contains confidential and legally privileged
information, and it is intended only for the use of the addressee. Access to this email by anyone else is
unauthorized. If you are not the intended recipient, any disclosure, copying,
distribution or any action taken in reliance on it is prohibited and may be
unlawful. If you received this communication in error please notify us
immediately and destroy the original message.
Thank you.</span></div></div></div></div></div></div></div>
</div>