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    <div class="moz-cite-prefix">Hi Martin,<br>
      <br>
      i tried the triangle filter in all cases - and yes - i works in
      all three cases. <br>
      <br>
      So is this "problem" of concave polygons inside VTK or in OpenGL?
      <br>
      <br>
      Best regards,<br>
      <br>
            Stefan<br>
    </div>
    <blockquote
cite="mid:CANXz0SajZXhxG+oC0k1Tby2nuNhRrzNVnE5dJpQnd3g9+h+MPw@mail.gmail.com"
      type="cite">
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      <div dir="ltr">I'm not sure if this is your issue, but you might
        try using a triangle filter on your data. For OpenGL we do not
        guarantee correct rendering of concave polygons. The triangle
        filter will convert a concave polygon into convex triangles
        which should render correctly.</div>
      <div class="gmail_extra"><br>
        <div class="gmail_quote">On Tue, Oct 18, 2016 at 2:20 AM, Stefan
          Melber <span dir="ltr"><<a moz-do-not-send="true"
              href="mailto:Stefan.Melber@dlr.de" target="_blank">Stefan.Melber@dlr.de</a>></span>
          wrote:<br>
          <blockquote class="gmail_quote">
            <div> Hi,<br>
              <br>
              i found a rendering problem with cuts through polyhedral
              cells depending on which rendering backend is used. For
              example in PV 5.1.2 compiled with<br>
              <br>
              VTK_RENDERING_BACKEND = OpenGL<br>
              <br>
              a cut looks like error.opengl.v5_1_2.png - there is a
              wrong shading and some facets coming from the wrong
              starting point.<br>
              <br>
              Switching to OpenGL2 everything is fine
              (error.opengl2.v5_1_2.png). This problem is the same with
              ParaView 5.2.0RC1 and OpenGL or OpenGL2 - however there
              seems to be an additional (smaller) problem using OpenGL2:
              there are some lines drawn outside of the shell - see
              error.opengl2.v5_2_0rc1.png (cutted on a different
              position).<br>
              <br>
              The example cell is for testing is attached as "error.vtk"
              - cut e.g. in x-direction on different positions to get
              the described effects.<br>
              <br>
              Best regards,<br>
              <br>
                     Stefan<br>
              <br>
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        <br>
        <br>
        <div><br>
        </div>
        -- <br>
        <div class="gmail_signature" data-smartmail="gmail_signature">Ken
          Martin PhD
          <div>Chairman & CFO<br>
            Kitware Inc.<br>
            28 Corporate Drive<br>
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            518 371 3971
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