Performance problem

[Vladimir Baltchev]

  The combination OpenGL X11 works fine on Unix. We are trying to use 
cygwin to port our applications on Windows. The cygwin's OpenGL gives us 
the dependency on the X11 cygwin simulation on Windows which is slow, I 
gess...

-----------------
If I am interpreting the output below correctly, you are developing an 
OpenGL program under X11; that's the main reason it is so slow.

OpenGL under X11 renders everything in software, without any hardware 
acceleration, so it's rendering is orders of magnitude slower. It is 
true that Cygwin's I/O and memory management are somewhat slower than 
under Linux, but that's peanuts compared to the OpenGL penalty.

If you want a fast program, you will have to use Window's native OpenGL 
implementation, which renders through hardware accelerators. That's what 
the OpenGL package for Cygwin provides.

Unfortunately, to use Window's native OpenGL implementation, you will 
have to rewrite completely such parts of your program as window 
management and user interface.

Last point (before you ask): the OpenGL implementation under X11 cannot 
be easily modified to use hardware acceleration, and I doubt it can be 
modified at all to do so. To know why, please search the archives for 
this list.

Vladimir Baltchev <vbaltch at orthosoft dot ca> wrote:

    Hi there,
    We are about to port Unix - Irix and Linux applications to Windows
    using Cygwin. However the Cygwin version is very slow compared to
    Linux, even I compiled with the optimize option -O2. It is a Windows
    2000, the program is a segmentation editor using Qt, OpenGl and some
    image processing.
    What is the reason? Is it OpenGL on cygwin, or both?
    Here is the library dependency list:
    segeditorMax.exe
    C:\cygwin\usr\X11R6\bin\libGL.dll
    C:\cygwin\usr\X11R6\bin\libX11.dll
    C:\cygwin\bin\cygwin1.dll
    C:\winnt\System32\KERNEL32.dll
    C:\winnt\System32\NTDLL.DLL
    C:\cygwin\usr\X11R6\bin\libXext.dll
    C:\cygwin\usr\X11R6\bin\libGLU.dll
    c:\qt-cygwin\qt-3\bin\cygqt-mt-3.dll
    C:\cygwin\usr\X11R6\bin\libICE.dll
    C:\cygwin\usr\X11R6\bin\libSM.dll
    C:\cygwin\usr\X11R6\bin\libXrender.dll
    C:\cygwin\bin\cygpng12.dll
    C:\cygwin\bin\cygz.dll
    C:\winnt\System32\ADVAPI32.DLL
    C:\winnt\System32\RPCRT4.DLL
    c:\Vlad\build\Dev\lib\libOip.dll
    C:\winnt\System32\GDI32.dll
    C:\winnt\System32\USER32.DLL 




André Bleau, Cygwin's OpenGL package maintainer.


-- 
Vladimir Baltchev
Senior Software Developer @ Orthosoft R&D Inc
Tel (514) 861-1837 ext 230
Email: Vladimir.Baltchev@orthosoft.ca

-- 
Vladimir Baltchev
Senior Software Developer @ Orthosoft R&D Inc
Tel (514) 861-1837 ext 230
Email: Vladimir.Baltchev@orthosoft.ca



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