A Letter to the Open Source Community
In January 2000, SGI released the OpenGL Sample Implementation (SI) to the open source community. This release, together with the earlier open sourcing of the GLX subset of the SI in 1999, cleared the way for developers to produce high-quality hardware-accelerated OpenGL drivers for the Linux platform.
We released the SI under a very liberal license, the "SGI Free Software License B". While the release was enthusiastically received, several key figures in the open source community pointed out that clause 2.4 in version 1.0 of the license agreement was incompatible with the open source license used by XFree86 and Mesa. The intent of clause 2.4 was to prevent modifications to the SI that would "break" the OpenGL API.
We've responded to this criticism because our intention was to genuinely open source the SI and to work with the open source community to ensure the availability of quality OpenGL drivers for Linux. Our lawyers reviewed the agreement and agreed to remove clause 2.4, together with several minor related changes. The complete text of the old and new versions of the license can be found on SGI's open source website at
The result is that the SGI Free Software License B is now acceptable to both the XFree86 Project, and to Brian Paul on behalf of Mesa developers.
As mentioned above, the reason for this clause was to preserve the integrity and stability of the OpenGL API, so that it will continue to serve as a true crossplatform standard with many different implementations. To help ensure that goal, SGI has worked with other groups that are developing open source implementations of the OpenGL API. Today we are making a joint position statement which will continue to further our aims:
Joint Statement Regarding Stability of the OpenGL API
SGI, Brian Paul (Mesa principal author and copyright holder), and Precision Insight Inc. (the most active open source development group currently working with both Mesa and SGI code), agree not to accept any modifications into the official OpenGL Sample Implementation or Mesa code bases which would break compatibility with the OpenGL API as defined by the OpenGL Architecture Review Board.
We encourage developers to take advantage of one of OpenGL's key strengths, its extension mechanism, to support new hardware features. Following the ARB's extension guidelines has the major benefits that a formal description of the extension is maintained in the OpenGL extension registry, and that the extension is well specified, so it can be implemented properly in a wide range of drivers. The registry and guidelines are located at:
Anyone wishing to evolve the Mesa or SI codebases in a different direction that breaks the API can of course fork them and maintain their own, incompatible version; however, such forks are unlikely to be viable or to attract developers and applications, and we strongly recommend against doing this.
We have taken this joint stance because it will result in the preservation of the integrity, stability and value of OpenGL as a cross-platform API. We look forward to a continued positive and productive relationship between SGI and the rest of the open source community that will continue to make OpenGL successful everywhere.
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