title: vtk error: extension `GL_EXT_gpu_shader4' unsupported in fragment shader
body: <p>I have XUBUNTU 16.04 32 bits. I am a beginner with VTK libraries. I have built and istalled VTK 7.1.1 from source. I followed the instructions from <a href="https://www.vtk.org/Wiki/VTK/Configure_and_Build" rel="nofollow noreferrer">https://www.vtk.org/Wiki/VTK/Configure_and_Build</a>
  The installation is ok. No errors.
  I download the simplest example: <a href="https://lorensen.github.io/VTKExamples/site/Cxx/Rendering/CylinderRenderingProperties/" rel="nofollow noreferrer">CylinderRenderingProperties</a>.
  Then, I compile the example. No errors. But, when I run the program</p>
  
  <pre><code>./CylinderRenderingProperties
  </code></pre>
  
  <p>there is an error:</p>
  
  <pre><code>VTK-7.1.1/Rendering/OpenGL2/vtkShaderProgram.cxx, line 395 vtkShaderProgram (0x9fd1510): 0:39(12): error: extension `GL_EXT_gpu_shader4' unsupported in fragment shader
  </code></pre>
  
  <p>I don't know what is wrong. Could be related with any graphic driver? This is the information of my graphics hardware: </p>
  
  <pre><code>inxi -G
  Graphics:  Card: Intel Mobile 4 Series Integrated Graphics Controller
         Display Server: X.Org 1.19.3 drivers: (unloaded: fbdev,vesa)
         Resolution: 1280x800@60.00hz, 1280x1024@60.02hz
         GLX Renderer: Mesa DRI Mobile Intel GM45 Express x86/MMX/SSE2 GLX Version: 2.1 Mesa 17.0.7
  </code></pre>