Summary of Discussion Topics

• Fahrenheit Statements
• OpenGL 1.2 Specification Approval
• GLX 1.3 Specification Discussion
• Dinner
• FORTRAN 90 Bindings
• GLUT Status
• Addison-Wesley Books
• Schedule for 1.2 Sample and Conformance Tests
• OpenGL 1.2 Specification Approval
• Conformance Tests
• Conformance Proposals
• ARB and Other Extensions
• Java Bindings Status

Monday, March 9

Fahrenheit Statements

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

• An agreement between SGI and Microsoft, parts of which were also with Intel and HP, to define three new APIs:
  • Low Level - Windows-specific and tightly bound to DirectX
  • Scene Graph - available at least on Windows, Irix, and HP/UX; will run on OpenGL, D3D, and, eventually, FLL
  • Large Model Visualization - based on Scene Graph
• SGI and Microsoft working to improve OpenGL support on Windows. This includes higher quality drivers, OpenGL 1.2 drivers, and a new driver license agreement for Windows IHVs.
• SGI and Microsoft will be less combative in public - there will be no more "official" OpenGL/D3D wars.

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++?

• Good for OpenGL:
  • FLL will not be ported outside Windows.
  • Microsoft has committed to supporting OpenGL for a long time - well past FLL introduction.
  • The agreements and the new driver development process will make OpenGL attractive on Windows.
• SGI will no longer be able to push OpenGL++ (though they have no objection to others picking up the work). Resources are committed to work with Microsoft and HP on the scene graph and large model visualization APIs.

Steve Wright from Microsoft followed up:

• Different groups in MS had different stories. OpenGL was successful at professional apps, but there was tension with the DirectX group. The realignment within MS strengthens the story.
• Some of you will apply OpenGL in other (non-professional) markets. There's a reasonably good chance of making this work.
• All managers at least up to the level of Jim Allchin are in favor of indefinite support for OpenGL and ongoing support for cross-platform apps using it.
• Lots of DDK license agreements have been signed in the last few months since the announcement.
• Most vendors will want to track FLL as well, but OpenGL isn't going to go away in 3 years.

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:

• #2.98 - A YES vote would modify the definition of CONSTANT_BORDER_MODE to apply the constant color after the convolution kernel. A NO vote would keep the existing definition in the spec, which convolves against constant-colored pixels outside the image boundaries. The vote was
  0 YES / 6 NO / 1 ABSTAIN
  Vote #2.98 failed.
• #3.98 - A YES vote would add WRAP_BORDER_MODE, as defined and implemented by Sun, to the spec. The vote was
  3 YES / 4 NO / 1 ABSTAIN
  Vote #3.98 failed.
• #4.98 - A YES vote would retain IGNORE_BORDER_MODE as defined in the draft spec. A NO vote would remove IGNORE_BORDER_MODE. The vote was
  2 YES / 4 NO / 1 ABSTAIN
  Vote #4.98 failed.

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:

• Secondary color - explicitly specifying the secondary color when GL_LIGHTING is disabled. This is for apps that want to compute their own lighting. There is a candidate specification and several licensees expect to support it. Considerable interest.
• Vertex-indexed fog - explicitly specifying the fog weighting factor at each vertex, rather than relying on Z. This might build on secondary color by using the otherwise relatively useless alpha component, or might involve a separate piece of state. Considerable interest.
• With the advent of hardware-accelerated rasterization, some IHVs are interested in revisiting Microsoft's EXT_clip_volume_hint. This was withdrawn several years ago because the performance gain is minimal for software implementations, but some vendors may want to support it now.
• Multitexture needs to be finalized very soon; there is a lot of pull from IHVs who are building multitexture hardware. David Blythe discussed possible changes in his draft spec since December:
  • Decouple number of texcoords from number of active textures - this has already been done.
  • Add new environment functions - SUBTRACT, REVERSE_SUBTACT, ADD.
  • The spec needs to say something about clamping and range in the texture units.
  • It's currently a linear pipeline; there's some interest in supporting more general routing of the texture units and more general input selection. For example, fragment color might be selected as a possible input at each stage.

  Multitexture will be pursued by email and otherwise offline by interested IHVs and ISVs. Nvidia will host a first meeting in Sunnyvale next week,

• Lots of interest in fragment lighting. SGI needs to promulgate specs and decided what parts are proprietary and what parts will be made available to licensees.

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!