Re: [Plib-users] Where does plib look for gl.h?

[Steve B. <sjb...@ai...>]

Darrell Blake wrote:
> I can't get plib to find gl.h and I know for a fact that OpenGL is 
> installed because XScreensaver compiled and works fine with GL 
> screensavers. When I run "find / -name gl.h" this is what I get...
> 
> /usr/lib/opengl/xfree/include/GL/gl.h
> /usr/lib/opengl/xfree/include/gl.h
> /usr/X11R6/include/GL/gl.h

Those are *all* incorrect!

   /usr/include/GL/gl.h

...that's a part of the OpenGL standard for Linux.  Most other OS's
put it somewhere like that too.

I worked on the committee that decided this.

OpenGL doesn't have to be a part of X11/X11R6/xfree - there are new
cellphones and PDA's that run Linux and have OpenGL implementations -
but which DON'T run X.  For those systems, it would be nonsensical to
put gl.h in any directory with X11/X11R6 or xfree in it's path - and
since we'd like all OpenGL programs to only have to look in a single
place, it should be in a system level directory.   /usr/include is
where these things belong,   /usr/include/GL is the standard.

Please stick to it!

> Where does plib look for gl.h because I can create a symlink to the 
> location.

PLIB looks in /usr/include/GL/gl.h - but if it can't find it there, it
goes on to looks in /usr/X11/include/GL/gl.h. That's because some older
Linux distro's (incorrectly) put GL in the X11 tree.

FYI:  The library for OpenGL should be in /usr/lib/libGL.so - and nowhere else.
The GLU, and GLUT/freeglut libraries should be in the same places as OpenGL itself.

It's a very bad idea indeed to allow your system to get polluted with copies of
things like this because when you upgrade something, you are very unlikely to
catch all of the copies and you'll find some programs picking up old copies.

That's very hard to diagnose - so I *STRONGLY* recommend that you do a 'find'
on gl.h and libGL.so and delete all of the copies that are in non-approved
places.

---------------------------- Steve Baker -------------------------
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