The OpenGL Pipeline Newsletter - Volume 002
Table of Contents
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As of September 21st, 2006, the OpenGL Architecture Review Board (the ARB) has ceased to exist. As described in the previous issue of OpenGL Pipeline, OpenGL API standardization has moved to Khronos, and will take place in the new OpenGL ARB Working Group (WG). We've retained the ARB label as a historical nod, so it makes sense to continue using the "ARB" suffix in extensions the group approves.
After holding the job for nine years, Jon Leech decided to step down as the ARB secretary. Barthold Lichtenbelt has been elected unanimously to lead the ARB. A big thank you to Jon for a job well done!
In general, the ARB WG will operate very much like the old, independent ARB. One great advantage of joining Khronos is closer collaboration with our sister working group, the OpenGL ES working group. This working group develops an API based on OpenGL and the OpenGL Shading Language for the handheld and embedded markets. Before joining Khronos, swapping ideas with the OpenGL ES group was difficult, mainly due to IP concerns. That barrier is now gone. Another huge benefit to joining Khronos is the extra support the ARB gets in the form of professional marketing and clout that comes with being associated with the Khronos name. Procedurally, not much changes. The Khronos bylaws and procedures differ in minor ways; the only major change is a final review and signoff performed by the Khronos Board of Promoters on any specifications the ARB WG develops.
The main task for the ARB is to deliver two new OpenGL releases in 2007. The first one, code named OpenGL "Longs Peak" (the actual releases will have version numbers), is slated to be released in summer 2007. The second one, code named OpenGL "Mt. Evans", is targeted for an October 2007 release. Why code names? We want to give the ARB's marketing group a chance to think through what the right names would be for these releases. Too many suggestions have already been made, including OpenGL 2.2, OpenGL 3.0, OpenGL 3.1 and even OpenGL 4.0. This is not the time yet to pin down the version number, and therefore we'll be using code names.
OpenGL Longs Peak will be a significant departure for us. While there will still be backwards API compatibility, the new "Lean and Mean" profile, and a substantial refactoring in terms of the new object model, make it in many ways an entirely new API design. This is an ambitious task and requires a high degree of commitment from the ARB members. We are already seeing some welcome participation from Khronos members who were not members of the old ARB, and hope to see much more.
While OpenGL Longs Peak will be implementable on current and last generation hardware, OpenGL Mt. Evans will only be implementable on the newest hardware available. The OpenGL Mt. Evans release will be a continuation of OpenGL Longs Peak, with a lot of new functionality added. Some of the highlights are: geometry shading, a more central role for buffer objects, and a full integer pipeline accessible via the OpenGL Shading Language.
Why two new OpenGL releases do you ask? This split in two makes it easy for ISVs to develop a new title spanning a wide range of graphics hardware. By coding their core rendering engine to OpenGL Longs Peak, both older and the newest hardware will be covered. By then coding incrementally to the OpenGL Mt. Evans API, the newest hardware can be exploited to its maximum potential.
Lastly, here is more detail about the ARB Working Group organizational structure. The ARB WG contains a top-level Steering Group (SG) and a number of "Technical Sub-Groups" or TSGs. Each TSG focuses on a specific area and has its own chairman. At present, the responsibilities and structure of the ARB WG include:
- OpenGL ARB Steering Group (Chair: Barthold Lichtenbelt, NVIDIA)
- The top-level SG will define the overall OpenGL strategy and timeline; liaise with the OpenGL ES Working Group; develop conformance tests; and perform any other major functions not assigned to one of the TSGs.
- Ecosystem TSG (Chair: Benj Lipchak, AMD)
- The Ecosystem TSG will develop the OpenGL SDK, in cooperation with many external projects and developers who are contributing to this effort; write developer documentation; develop naming conventions; define the partitioning between the core OpenGL Longs Peak "Lean and Mean" profile and the compatibility layer for OpenGL 1.x/2.x; support outside efforts such as the subsidy program for academic users of Graphic Remedy's gDEBugger; and perform some marketing functions, such as this OpenGL Pipeline newsletter.
- Object Model TSG (Chair: Barthold Lichtenbelt, NVIDIA)
- The Object Model TSG will define the new object model; figure out how existing OpenGL functionality such as framebuffer objects, program objects, texture objects, etc. will be expressed in the new model; and define small bits of entirely new functionality such as sync objects. This is where most of the work for OpenGL Longs Peak will take place.
- Platform TSG (Chair: Jon Leech)
- The Platform TSG will define the GLX and WGL APIs and GLX stream protocol; liaise with the Khronos OpenKODE Steering Group to provide requirements for the EGL API (a platform-neutral analog of GLX and WGL); and handle topics related to OS integration such as Application Binary Interfaces, Device Driver Interfaces, or reference source code for link libraries and shim layers.
- Shading Language TSG (Chair: Bill Licea-Kane, AMD)
- The Shading Language TSG will be responsible for all aspects of the OpenGL Shading Language, including new functionality needed in both the Longs Peak and Mt. Evans releases. This TSG will also liaise with OpenGL ES Shading Language work taking place in the Khronos OpenGL ES Working Group.
- Next Gen TSG (Chair: Jeremy Sandmel, Apple)
- The Next Gen TSG will be responsible for all aspects of the Mt. Evans API design, keeping the new functionality aligned with the new object model being designed by the Object Model TSG.
In the remainder of this issue, there's more information about OpenGL Longs Peak and Mt. Evans, and about activity happening in some of the TSGs. We will continue to provide quarterly updates of what to expect in OpenGL and of our progress so far. But for now it's back to the teleconference salt mines. We have a very aggressive schedule to meet and don't want to disappoint!
OpenGL ARB Secretary, outgoing
Barthold Lichtenbelt, NVIDIA
Khronos OpenGL ARB Steering Group Chair, incoming