OpenGL

ARB Meeting Notes

March 9-10, 1998

Hosted by Evans and Sutherland in Salt Lake City, UT

Meeting notes taken by Jon Leech, SGI

Attendees

Allen Gallotta ATI alleng@atitech.com
Bill Armstrong Evans & Sutherland armstron@es.com
Bimal Poddar Intel bpoddar@pcocd2.intel.com
Brett Johnson HP brett@fc.hp.com
Bruce D'Amora IBM damora@austin.ibm.com
Colin Sharp Rendition colin@rendition.com
Craig Groeschel Metro Link craig@metrolink.com
Dale Kirkland Intergraph kirkland@ingr.com
Dan Brokenshire IBM brokensh@austin.ibm.com
David Blythe SGI blythe@sgi.com
David Ligon Raycer Graphics dligon@raycer.com
David Yu SGI dyu@sgi.com
Dick Jay TGS jay@tgs.com
Fred Fisher Dynamic Pictures arb@dynamicpictures.com
Garry Paxinos Metro Link pax@metrolink.com
Igor Sinyak Intel igor_sinyak@mail.intel.com
Jack Middleton Sun jack.middleton@eng.sun.com
Jan Hardenbergh MEITCA jch@merl.com
Jeremy Morris 3DLabs jeremey.morris@3dlabs.com
Jim Cobb PTC jcobb@ptc.com
Jon Leech SGI ljp@sgi.com
Kurt Akeley SGI kurt@sgi.com
Mahesh Dandapani Rendition mdi@rendition.com
Matt Papakipos Nvidia papakipos@nvidia.com
Michael Gold Nvidia gold@nvidia.com
Miriam Geller SGI miriamg@sgi.com
Nate Robins University of Utah nate@cs.utah.edu
Nathan Tuck Raycer ntuck@raycer.com
Paul Jensen 3dfx pgj@3dfx.com
Richard Pimentel PTC rpimente@ptc.com
Richard Wright Real3D wrightr@real3d.com
Steve Wright Microsoft swright@microsoft.com
Tim Kelley Real3D kelleyt@real3d.com

Summary of Discussion Topics


Monday, March 9

Fahrenheit Statements

Kurt Akeley from SGI summarized Fahrenheit. There are three components:

SGI felt it was critical to work together with Microsoft, which had not been moving in compatible directions, to be able to build value-added products in the Windows environment. Fahrenheit is a large step in that direction.

The ARB has made several attempts to get agreement on high-level APIs, and has overall failed, sometimes in a frustrating manner. SGI's experience is that apps need to write to a scene graph to get good performance without micro-optimization. But it's also important to be able to "reach around" the scene graph to the low level. SGI's motivation with Fahrenheit was primarily to get agreement on a good scene graph.

What happens with OpenGL and OpenGL++?

Steve Wright from Microsoft followed up:

OpenGL 1.2 Specification Approval

This was the major activity of the meeting, taking most of the day and being continued Tuesday morning. Rather than taking detailed minutes of the discussions, a separate summary of the changes to be applied to the final pre-meeting draft of the spec is provided.

DEC was unable to attend this meeting; they were brought in at times for conslution and votes by teleconference. This was especially important since most of the major issues remaining with the specification were raised by Andy Vesper at DEC.

One significant item had to be decided by ARB vote: the set of convolution border modes to be included in OpenGL 1.2, and the exact definition of those modes. The three votes were:

GLX 1.3 Specification Discussion

David Yu led this discussion. GLX 1.3 still has a number of open issues to be resolved, which are summarized in the GLX minutes.

The GLX protocol document has not yet been updated based on the protocol for the OpenGL 1.1 extensions on which 1.2 features were based.

GLX discussion will be continued on the mailing list.

Dinner

Bill Armstrong organized dinner at the Old Salt City Jail.


Tuesday, March 10

FORTRAN 90 Bindings

Bill Mitchell's FORTRAN 90 bindings were approved by the ARB in February. The specification is kept on opengl.org, and his sample implementation is available from http://math.nist.gov/f90gl/.

GLUT Status

As many people know by now, GLUT author Mark Kilgard is no longer working at SGI. This has led to some uncertainty regarding the status of GLUT. SGI stated its official position:

SGI believes that GLUT is a powerful tool for OpenGL programming, and wants to see it continue to evolve in the future. However, SGI does not own GLUT; Mark Kilgard holds the copyright and will determine what happens with GLUT through his actions.

SGI will continue to provide space for Mark's GLUT pages (http://reality.sgi.com/mjk/glut3/glut3.html) on its employee personal web server, as a service to the OpenGL community. Mark says that he's still working on a new GLUT revision (GLUT 3.7), despite his change in employment. When future GLUT versions appear, they will also be hosted on reality, if Mark so wishes.

Addison-Wesley Books

SGI expects to update the Red and Blue books for OpenGL 1.2, though details have not been finalized. The Green book (OpenGL Programming for the X Window System) was done by Mark Kilgard; we'll check with him to see if he plans to update it. Likewise for Ron Fosner's White book (OpenGL Programming for Windows 95 and Windows NT).

Schedule for 1.2 Sample and Conformance Tests

SGI is aiming at simultaneous release of 1.2 sample GL, conformance tests, and GLX 1.3 towards end of summer '98. Conformance proposals and the GLX 1.3 specification and protocol document must be completed in the near future, since they are required to finish the sample GL. Aid from other ARB members and licensees is welcome, particularly in finalizing conformance proposals and writing code for them.

OpenGL 1.2 Specification Approval

IBM noted that the sample GL sets the internal format of the proxy texture to 0 when the proxy query fails, while IBM's behavior is to set the internal format to the specified format. Do we want to change the sample? Tabled for now.

DEC was brought in by teleconference for most of this discussion. After deciding on a few final points, a vote for approval of OpenGL was held. The vote was on the March 4 draft together with the list of changes resulting from the discussion.

The vote was unanimous in favor; OpenGL 1.2 is approved. The final specification document will be posted by Jon Leech shortly after the meeting.

Conformance Tests

Both the general strategy of conformance testing and specific proposals for testing OpenGL 1.2 features were discussed.

David Yu & Dan Brokenshire discussed the GLX conformance shell, in particular how to test all potentially possible FBConfigs. This is complicated and will be taken offline.

Dan Brokenshire expressed some willingness by IBM to share the load of developing conformance test code (as well as specs).

Dave Ligon asked about OPC posting of conformance tests. We've previously established that OPC is not willing to do this. Another possibility, posting on opengl.org, raises a conflict of interest issue - opengl.org is funded by SGI. However, SGI is willing to set up links from opengl.org to vendor-hosted conformance results.

There was limited interest (5 people) in public posting of conformance results. IHVs can get Windows conformance binaries and sources through Microsoft. Unix vendors can choose or not to publish their results.

Evans & Sutherland raised the issue of minor problems with conformance. The big issue appears to be the lag between submitting bugs to the ARB and the resulting updated conformance suite passing through SGI to Microsoft and WHQL. People should discuss this with Steve Wright if the lag in fixes is a problem.

Suggested changes (diffs, included files) to conformance tests should be sent to opengl-licensees@sgi.com only, not opengl-arb-interest@sgi.com. But it's not a criminal act if an accident happens.

Conformance Proposals

The mustpass tests are really aimed at making sure that implementations don't omit features, while the 'regular' conformance tests establish accuracy. We need to discuss this on opengl-arb-interest after the meeting, to establish a clear demarcation of mustpass from conformance tests. Jon Leech will push this after the ARB meeting.

All tests should add their enumerants and functions to a 1.2-specific coverage test. Imaging features will be tested only if the implementation supports the imaging subset (as defined by the GL_EXTENSIONS string).


Feature Current Proposal Comments
BGRA Pixel Formats (SGI) bgra_test.txt
Convolution Border Modes
(Sun & HP)
border_test.txt
Draw Range Elements (SGI) drawrange_test.txt Might this go into primtest? There's no existing test for DrawElements().
Packed Pixel Formats (Nvidia) packed_test.txt The problem is the large number of formats supported.
Rescale Normal (IBM) rescale_test.txt The proposal suggests modifying the xformn test, which we probably don't want to do. Create a parallel test specific to rescale_normal instead?
Separate Specular Color (E & S) specular_test.txt E & S feels that mustpass should test minimal functionality, not comprehensive. Bill is reluctant to put in new color clipping requirements on the secondary color that aren't there for the primary color. He'll look more closely at mustpass. Bimal thinks there are no color clipping tests in the 1.1 suite. However, IBM & Intel both feel that simple clipping tests would be appropriate.
Texture Edge Clamp (SGI) To Be Done
Texture LOD (SGI) To Be Done
Texture 3D (Real 3D) texture3D_test.txt As a PC vendor driven by WHQL testing, Real 3D was not totally clear on the distinction between mustpass and "GLLite" tests, and how this maps onto mustpass / conformance tests.
Imaging Subset Features
Blend Color
Blend Equation (SGI)
blend_test.txt
Color Matrix (SGI) colormatrix_test.txt
Color Table
Color Subtable (SGI)
colortable_test.txt Should be split into mustpass and conformance components.
Convolution (SGI) convolution_test.txt Should be split into mustpass and conformance components - there are a total of 9 tests.
Histogram
Minmax (SGI)
histogram_test.txt
minmax_test.txt
To Be Done
GLX Extensions
FB Config (SGI) To Be Done
Make Current Read (SGI) To Be Done
Pbuffer (SGI) To Be Done

ARB and Other Extensions

The idea of ARB extensions is to have a new level of formalism and support beyond EXT. They will have a specification agreed on by the ARB, conformance tests, and a sample implementation provided with the sample GL. They do not have to be supported by licensees, and they are not part of the OpenGL specification itself.

Extensions discussed were:

Java Bindings Status

Sun is proceeding with AWT bindings for JDK as discussed in the December meeting. The bindings are to appear in JDK 1.2 beta 3. While Sun can't preannounce dates, the beta will probably ship in the next couple of months, and final will probably be available towards the end of summer '98.

Arcane Technologies is interested in submitting Magician, their Java bindings, to the ARB as a standard. They prepared a document describing the Magician interface which was distributed at the meeting, and will attend the June ARB meeting to discuss the proposal. In the meantime, the ARB will discuss Magician with Arcane via the opengl-arb-interest list, to learn more about it and about the conditions under which it may be made available to licensees and the ARB.

Thanks to Evans & Sutherland for hosting this meeting!