<div dir="ltr"><div>Hi,</div><div><br></div>You will need to share more code in order to get help.<div>The test I mentioned is working perfectly here.</div></div><div class="gmail_extra"><br clear="all"><div><div class="gmail_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 4:46 PM, Ken Martin <span dir="ltr"><<a href="mailto:ken.martin@kitware.com" target="_blank">ken.martin@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">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"><div><div class="h5"><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/vtkWindowTo<wbr>ImageFilter.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_-6164885676496862913m_-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_-6164885676496862913m_-3959379645480281864HOEnZb"><div class="m_-6164885676496862913m_-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_-6164885676496862913m_-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_-6164885676496862913m_-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_-6164885676496862913m_-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>
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