[mapserver-users] Using OGL rendering instead of AGG

[Lime, Steve D (MNIT)]

The OpenGL render is quite old and hasn't been maintained properly - especially in light of the major graphics refactoring done with 6.x. We should probably deprecate it at this point. 

Anyway, I don't think you'll have much luck with OpenGL without a good bit of work. I'm not sure that would speed thing up in your case. The pixel-by-pixel expression processing is probably what's killing you. It would make more sense to work on other types of optimizations. Perhaps pre-processing  or re-organizing the DEM data or using lookup tables instead of expressions. 

Lots of good information here: http://mapserver.org/input/raster.html.

Steve

-----Original Message-----
From: mapserver-users [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of ramchandra
Sent: Tuesday, July 25, 2017 6:14 AM
To: mapserver-users at lists.osgeo.org
Subject: [mapserver-users] Using OGL rendering instead of AGG

Hi All,
     I am trying to color classify a DEM by adding multiple styles to the
layer entry in the map file using the PIXEL value as the EXPRESSION. I am
trying to speedup the rendering of the styled layer. I tried using the
Hardware accelerated rendering through OpenGL. I have added the cmake flags
so that OpenGL binaries are loaded when building Mapserver. 
I also made changes in the source code to enable the OGL Rendering by
setting the MACRO #USE_OGL to 1. I have also changed my OUTPUTFORMAT as
follows to trigger opengl rendering.
OUTPUTFORMAT
    NAME "OGL_PNG24"
    DRIVER "OGL/PNG"
    IMAGEMODE RGB
  END # OUTPUTFORMAT
In-spite of doing all these when i am sending the request it appends a new
OUTPUTFORMAT object with AGG Driver as follows.
OUTPUTFORMAT
    NAME "png"
    MIMETYPE "image/png"
    DRIVER "AGG/PNG"
    EXTENSION "png"
    IMAGEMODE RGB
    TRANSPARENT FALSE
  END # OUTPUTFORMAT

It also changes my OGL OUTPUTFORMAT by adding the additional fields MIMETYPE
and EXTENSION.
  OUTPUTFORMAT
    NAME "OGL_PNG24"
    MIMETYPE "image/png; mode=24bit"
    DRIVER "OGL/PNG"
    EXTENSION "png"
    IMAGEMODE RGB
    TRANSPARENT FALSE
  END # OUTPUTFORMAT

When I debug the code I see an error when the OGL output format block is
parsed.
The error says "OGL_PNG24 driver is not configured". 
Can anyone point out what might me causing this error or how to enable
OpenGL based rendering.

Regards,
Ram



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