Re: Performance problem

[Andre Bleau <bleau at igb dot umontreal dot ca>]

Vladimir Baltchev <vbaltch at orthosoft dot ca>  wrote:

> In fact you have 3 gl.h in cygwin but only one library - libGL, and it's 
> the X11 one...

Nope. There is also libopengl32.a (in /usr/lib/w32api). That's the one used 
by the OpenGL package, and the one using hardware acceleration if available.

and:

> OK, guys,
> I understand what Andre is saying, but he said cygwin is offering an 
> opportunity to use a OpenGL package different from the X11 one.

Exact.

> In fact I am trying to use cygwin to avoid havy porting effort. Obviousely 
> OpenGL on cygwin is slow

Slow under X11 only.

> and I'll forget about cygwin if I have to rewrite the application...
> Anyways, thanks for the help
> Vlad

Larry Hall <cygwin-lh at cygwin dot com> wrote:

> Vladimir,
>
>
> I think you're a little too fixated on the portability aspects such that
> you're not really processing what Andre is saying.  If you want
> absolute minimal porting changes, the route you took is the proper one,
> but you will suffer extreme performance degradation due to the fact that
> all of the processing for GL will happen in software.  If this isn't
> acceptable to you, then you do need to do more porting so that you're
> application works with Windows rather than X.

Exact.

>  For that, you can go 100%
> native Windows with your entire application

I think Larry means D3D here.

> or you can use the OpenGL
> package in Cygwin so that you only need to port the GL portion.

In fact, it's the converse. With the OpenGL package, the GL portion will be 
100% compatible, so it won't need any porting. It is the window management 
and user interface that will need to be ported.

> There is
> no libGL with Windows implementation of GL or in the OpenGL package that
> comes with Cygwin so I wouldn't waste any time trying to figure out why
> you can't find one outside of the X package.
> HTH,
>
> Larry

You may try to find some commercial, X11 server supporting hardware 
acceleration for OpenGL. The XFree86 server of the Cygwin distribution is 
not such a server.

The other way to build a portable application would be to use some OS 
independent layer such as GLUT and its GLUI derivative. Both are part of 
the OpenGL package.



André Bleau, Cygwin's OpenGL package maintainer.

email: bleau at igb dot umontreal dot ca
(Fight SPAM: encode your email-address)

Please address all questions and problem reports about Cygwin's OpenGL 
package to cygwin@cygwin.com . 


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