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<div>I am observing some odd results with volume rendering using ParaView 4.3.1 and ParaView master on OS X machines with NVIDIA graphics cards including a Geforce 650m in a macbook pro and a Quadro K5000 in a mac pro. On the mac pro, changing between the NVIDIA
web driver and OS X default driver has no effect. </div>
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1) After loading a vtkImageData file and selecting the volume representation and the GPU based volume rendering mode, the image disappears. The other volume rendering modes show the image correctly. I also tried building ParaView master with the OpenGL2 rendering
backend and in that case the GPU based volume rendering mode displays only some of the surfaces (2-4, the exact number depends on the camera position) and not the entire volume.</div>
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2) I also tried loading a small vtkStructuredGrid (attached) into ParaView master built with the OpenGL2 rendering backend and get the warning below. There are substantial artifacts that are not present when the OpenGL rendering backend is used. These artifacts
don’t appear when I load the same file in ParaView 4.3.1 or ParaView master build with the OpenGL rendering backend.</div>
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Warning: In ../VTK/Rendering/VolumeOpenGL2/vtkOpenGLProjectedTetrahedraMapper.cxx, line 151</p>
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vtkOpenGLProjectedTetrahedraMapper (0x7fdc49d3a140): Missing FBO support. The algorithm may produce visual artifacts.</p>
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<p style="margin: 0px;">I tried running glxinfo and under OpenGL extensions it does list GL_ARB_framebuffer_object, GL_ARB_draw_buffers and <span style="line-height: 16.7999992370605px; white-space: pre; widows: 1; background-color: rgb(255, 255, 255);">GL_ARB_texture_float</span>.
VTK, however, doesn’t appear to be detecting this.</p>
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<p style="color: rgb(0, 0, 0); margin: 0px;">Sincerely,</p>
<p style="color: rgb(0, 0, 0); margin: 0px;">Steven Hahn</p>
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