[GRASS-dev] [GRASS GIS] #3600: m.nviz.image doesn't produce any output

[GRASS GIS]

#3600: m.nviz.image doesn't produce any output
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  Reporter:  guano        |      Owner:  grass-dev@…
      Type:  defect       |     Status:  new
  Priority:  normal       |  Milestone:
 Component:  Default      |    Version:  7.0.4
Resolution:               |   Keywords:
       CPU:  Unspecified  |   Platform:  MacOSX
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Comment (by hcho):

 Only Windows defines double buffering; that's why Linux works without
 buffer swapping because it has only one buffer. BUT, glGetError() still
 returns GL_INVALID_OPERATION according to https://www.khronos.org/registry
 /OpenGL-Refpages/gl4/html/glReadBuffer.xhtml. Probably, that's why some
 Linux drivers and MacOS don't work at all.

 Windows is also broken because nviz draws to the back buffer, but it reads
 from the front buffer without buffer swapping.

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Ticket URL: <https://trac.osgeo.org/grass/ticket/3600#comment:54>
GRASS GIS <https://grass.osgeo.org>