Original GLUT library is open source, even on GitHub, yet the license doesn’t allow any changes to be released publicly (but you can change it for use in your own projects, as is often exercised in various tutorials still using GLUT itself). Most files contain this notice:
/* This program is freely distributable without licensing fees and is
provided without guarantee or warrantee expressed or implied. This
program is -not- in the public domain. */
It’s not maintained anymore, and because of this, freeGLUT exists, which implements GLUT interfaces and adds some features to work around its limitations.
Why would anyone want such a license for any open source project?
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Why would anyone want such a restricted license?
Quite simply,
control. And possibly, ego, positioning, financial, and
other advantages that derive
from control.
Over the last twenty years, numerous organizations have offered access to
code on generous, “please use it, learn from it,
enhance it, and pass it on!”
terms. The GNU Public Licence,
Apache, and other open source
licences have been part and parcel of this.
But a lot of code has been, and still is, offered on terms that, despite
a dollop of generosity (e.g. monetarily free to use, or free to
use under some conditions) and thus not being
completely proprietary, have key limitations
on how one can use, modify, and share it. They do not enjoy a full measure
of “free” in the sense of liberty.
Even within today’s evolved “open source
community,” it’s very common for developers to
reserve rights
(e.g. to
use of a trademark or validation suite, or the
unique ability to issue separate commercial
licences),
in order to retain control
and economic advantages for the originator.
If GLUT were a brand new open source project,
the limitations on its terms and
conditions
might be a little more surprising. But
it arrives from a very different time. Starting
twenty years ago, it predates
both The Internet and today’s open source culture.
The
GPL existed
at the time, but neither it nor its “share and share alike!” philosophy
were particularly widespread then. It was very rare
for software originating from commercial entities
like Silicon Graphics
(where GLUT, and GL overall, started).
Copyright statements offering
limited sharing with rights reserved
were much more common at the time.
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