OpenXR, glTF, OpenCL Next, and the Khronos Educators Program

The Khronos Group talked about several things at SIGGRAPH 2018. NNEF took up most of the first page. Rather than splitting them up into five posts, I combined the last four topics onto this single page:

  • The first public demo of OpenXR is available and on the show floor.
  • glTF Texture Transmission Extension is being discussed.
  • OpenCL Ecosystem Roadmap is being discussed.
  • Khronos Educators Program has launched.

The First Public Demo of OpenXR at the Show Floor!

OpenXR is expected to be the open VR and AR format for software to target. Its first announced, without a name, in December 2016. About four months later, in March, it was re-announced as OpenXR. There hasn’t been a whole lot of discussion in the seventeen months that followed, but it’s indeed progressing.

In fact, the first public demo is at SIGGRAPH. If you are at the show, then you will be able to see the old Epic Showdown demo in both StarVR and Microsoft Windows Mixed Reality headsets. I say “old Epic Showdown demo” because it, along with its sibling demo, Bullet Train, turned into Robo Recall, which has been out for a little while now.

OpenXR will be shown in two places:

  • The StarVR booth (#421) on the show floor and
  • The OpenXR BoF talk at 1pm, August 15th, in Marriott Pinnacle Ballrooms I-II.

One of the more important aspects of OpenXR is how it handles controller input. Rather than forcing some standard controller shape, the standard defines actions. It is up to the implementation to create an input system that feels comfortable with those actions, such as “Move”, “Jump”, and “Teleport” (which are the examples that the Khronos Group included in their press deck).

They are also collaborating with WebXR, moving this research into the Web.

glTF Texture Transmission Extension

glTF is a format for 3D assets that is focused on speed, small, and full-scene. The last part is key, because it leads to design goals that are unique from, for example, Autodesk FBX. It’s being adopted in many places, including even Microsoft Office. Also, TurboSquid has recently announced that they have added glTF to its StemCell initiative, which is a standard for stock 3D assets to be bought and sold.

But the current discussion is about their texture transmission format.

The goal is to have a standard that can sit between the original assets (PSD, etc.) and the GPU formats (BC1, BC5, ASTC, etc.). The announcement is not really news as much as it is “this is a very important topic happening right now – if you want to contribute – now now now now now!”

Check out glTF on their GitHub.

OpenCL Ecosystem Roadmap

There’s movement happening on the OpenCL front driven primarily by two issues:

  • OpenCL is not available everywhere
  • OpenCL is monolithic

With the first issue, some vendors have a major investment in OpenCL code, but they want to move it onto platforms where OpenCL isn’t officially supported. One example is Adobe, which pushed a lot of Photoshop code onto the GPU for Windows and macOS, but they cannot reliably use it on Android. Sure, some vendors, like NVIDIA and Samsung, have provided OpenCL drivers, but Google and others do not. What do they support? Vulkan. This lead to the Clspv project that we mentioned a while ago, but it hasn’t seen much usage outside of Adobe. What the Khronos Group wants is for other stakeholders to try their own kernels and report issues to evolve the project. They are also interested to know whether an OpenCL to Vulkan shim would gain traction. If so, they might be willing to host the project.

With the second issue, OpenCL requires too much. For instance, to be conformant, you need to have support for 32-bit IEEE 754 floating point values. That’s… rigid, and immediately shuts the door on, for instance, 8-bit DSPs. The Khronos Group is looking for ways to chunk the API into smaller segments, and to provide the mechanisms for software to query what they need (without breaking existing code). Obviously, this requires a lot of industry feedback, so that’s what they’re asking for.

Khronos Educators Program

Short note about this one. The Khronos Education Forum has just launched. It is a place where educators can discuss with the standards body, including the designers, directly. Any educator is welcome. It just requires an email to Khronos ( with your name, your institution, and a list of the Khronos Group standards that you wish to teach.

If you’re an educator, reach out! They want to help!

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