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libglut-devel package conflicts with opengl package [Attn: Volker]
- From: André Bleau <andre_bleau at hotmail dot com>
- To: <cygwin-apps at cygwin dot com>
- Date: Tue, 4 Nov 2008 11:48:02 -0500
- Subject: libglut-devel package conflicts with opengl package [Attn: Volker]
- Reply-to: <cygwin at cygwin dot com>
Again, with proper formating:
Following a user problem report (http://cygwin.com/ml/cygwin/2008-11/msg00022.html),
I just discovered that the last version of the libglut-devel package now installs a glut.h file
in /usr/include/GL (http://sourceware.org/ml/cygwin-announce/2008-03/msg00070.html). This
file takes precedance over the one in /usr/include/w32api/GL and declares the same functions
but with a different calling convention. This makes the packages libglut-devel and opengl
incompatible; you will have to uninstall one of them if you have both. libglut-devel is for
applications that will run through and X server while opengl is for application that will use the
native Windows interface, which is much faster.
The opengl package contains libraries related to openGL. One of them is GLUT (GL Utility
Toolkit), whose purpose is to provide an OS-independant way to get a graphic context for
openGL drawing, managing windows, and accessing devices like the keyboard and the mouse.
The version of GLUT in the opengl package interfaces directly with Windows, so it is very fast.
At first, the opengl package contained (among other things):
The glut32.dll, in /usr/bin
The include file glut.h, in /usr/include/GL
Concurrently, the w32api package included libglut32.a in /usr/lib/w32api . I don't know the
reason for this, as it is the only part of GLUT that the w32api provides. The w32api package is
a requirement for the opengl package.
Then the freeglut package was added to the distribution. Its purpose is to provide an
implementation of GLUT that runs through an X server. This created some conflicts
(http://cygwin.com/ml/cygwin-apps/2006-04/msg00079.html) that I resolved by creating an
updated version of the opengl package
(http://sourceware.org/ml/cygwin-announce/2006-04/msg00027.html) in which glut.h was
moved from /usr/include/GL to /usr/include/w32api/GL.
The applications using freeglut can be compiled and linked without problems, but I now realize
that native GLUT applications cannot be compiled correctly if the libglut-devel package is also
installed because the glut.h that it puts in /usr/include/GL takes precedance over the one that
is required in /usr/include/w32api/GL.
So, how do we solve this?
- André Bleau, Cygwin's volunteer OpenGL package maintainer.
Please direct any question or comment about the OpenGL package to cygwin at cygwin dot com