Thanks, Ken. I suspected most of this, but thanks for filling in the background and detail.
Again, I'm happy to let this go forward, just wanted to clarify how this can go more smoothly in the future, particularly re: putting this kind of thing in an Explainer and filing early w/ the TAG. Best, Alex On Wed, Sep 25, 2024 at 3:32 PM Ken Russell <k...@chromium.org> wrote: > Hi Alex, > > I don't want to speak for Jiawei but would like to provide a little more > background. This exposes a GPU hardware feature which allows the > application to specify additional clipping planes (in the form of distances > from the current vertex to each of those implicitly-specified planes) which > apply to geometry being drawn. The WebGPU API abstracts over this hardware > functionality, which is exposed by the underlying graphics APIs such as > Direct3D, Metal and Vulkan, on top of which WebGPU is implemented. > > I have not personally used this functionality, but > https://github.com/KhronosGroup/WebGL/issues/3109 captures a discussion > which motivated adding a similar extension to WebGL. The hardware feature > is faster, and provides higher quality visual results, than attempting to > emulate its behavior at the user level, which would generally be done by > discarding individual pixels in the fragment shader. > https://github.com/gpuweb/gpuweb/issues/390 contains the public > discussion adding the feature to WebGPU. > > It would be a fair amount of work to write up an explainer for every GPU > hardware feature that the WebGPU working group collectively agrees to add > either to the core specification or as an optional feature. In this and > many other cases there is no alternative to be considered; it's basically > either expose the hardware feature, or not. > > -Ken > > > > On Wed, Sep 25, 2024 at 2:22 PM Alex Russell <slightly...@chromium.org> > wrote: > >> Hey Jiawei, >> >> Thanks for filing this intent. It would be good if you opened explicit >> requests for position from Mozilla. We try not to impute stances based on >> WG conversations for a lot of reasons, but primarily because other engines >> have asked us not to. >> >> On TAG review, I agree that this is a small feature that doesn't need >> additional oversight and alignment, and I'll stand in on this one to say it >> looks OK. >> >> That said, it would be good to see an Explainer that outlines the value >> of the feature and how this will be used in real code to solve an important >> problem. Particularly if there were other alternatives considered. >> >> Also, asking for the TAG to look over something should come well before >> something lands in spec text, which is why our process recommends you begin >> that at Intent to Prototype phase. In this case, if you'd reached out when >> clipping was proposed, you would probably have already produced an >> explainer and gotten the TAG to indicate that they don't feel they need to >> review it, saving you time at this step. >> >> Best, >> >> Alex >> >> On Tuesday, September 24, 2024 at 7:25:54 PM UTC-7 jiawe...@intel.com >> wrote: >> >>> Done >>> >>> On Wednesday, September 25, 2024 at 8:06:02 AM UTC+8 vmp...@chromium.org >>> wrote: >>> >>>> Hey, >>>> >>>> Do you mind filing the reviews for other chips: >>>> [image: cs.png] >>>> >>>> Thanks! >>>> Vlad >>>> >>>> On Mon, Sep 23, 2024 at 11:07 PM Shao, Jiawei <jiawe...@intel.com> >>>> wrote: >>>> >>>>> *Contact emails* >>>>> >>>>> jiawe...@intel.com >>>>> >>>>> >>>>> *Explainer* >>>>> >>>>> The “clip-distances” GPU feature adds the WGSL built-in variable >>>>> @builtin(clip_distances) to allow a vertex shader to output user-defined >>>>> clip distances. https://github.com/gpuweb/gpuweb/pull/4588 >>>>> >>>>> >>>>> *Specification* >>>>> >>>>> https://gpuweb.github.io/gpuweb/#dom-gpufeaturename-clip-distances >>>>> >>>>> >>>>> *Summary* >>>>> >>>>> Adds the optional GPU feature "clip-distances" that allows setting >>>>> user-defined clip distances in vertex shader outputs. This technique is >>>>> particularly useful for the applications that need to clip all vertices in >>>>> a scene that are beyond a user-defined plane, such as many CAD >>>>> applications. >>>>> >>>>> >>>>> >>>>> >>>>> *Blink component* >>>>> >>>>> Blink>WebGPU >>>>> <https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EWebGPU> >>>>> >>>>> >>>>> *TAG review* >>>>> >>>>> None >>>>> >>>>> >>>>> *TAG review status* >>>>> >>>>> Pending >>>>> >>>>> >>>>> *Risks* >>>>> >>>>> >>>>> >>>>> >>>>> *Interoperability and Compatibility* >>>>> >>>>> This feature has been approved in W3C GPU for the Web WG meetings >>>>> including participants from Safari and Firefox. Related meeting minutes: >>>>> https://github.com/gpuweb/gpuweb/wiki/GPU-Web-2024-05-29#add-optional-feature-clip-distances-if-there-are-new-questions-4588 >>>>> >>>>> >>>>> >>>>> *Gecko*: No signal (Mozilla members have approved >>>>> https://github.com/gpuweb/gpuweb/pull/4588 and requested during >>>>> weekly standardization meetings that we postpone filing standard positions >>>>> until we reach Candidate Recommendation (CR) status in Q4) >>>>> >>>>> *WebKit*: Positive ( >>>>> https://github.com/WebKit/standards-positions/issues/294#issuecomment-1877411933 >>>>> ) >>>>> >>>>> *Web developers*: Positive ( >>>>> https://github.com/gpuweb/gpuweb/issues/390) >>>>> >>>>> *Other signals*: >>>>> >>>>> >>>>> *WebView application risks* >>>>> >>>>> *Does this intent deprecate or change behavior of existing APIs, such >>>>> that it has potentially high risk for Android WebView-based applications?* >>>>> >>>>> None >>>>> >>>>> >>>>> >>>>> >>>>> *Goals for experimentation* >>>>> >>>>> >>>>> >>>>> >>>>> *Ongoing technical constraints* >>>>> >>>>> None >>>>> >>>>> >>>>> >>>>> >>>>> *Debuggability* >>>>> >>>>> None >>>>> >>>>> >>>>> >>>>> >>>>> *Will this feature be supported on all six Blink platforms (Windows, >>>>> Mac, Linux, ChromeOS, Android, and Android WebView)?* >>>>> >>>>> No >>>>> >>>>> All platforms will eventually have support. Will immediately be >>>>> available on Android, Android WebView, ChromeOS, Mac, and Windows, where >>>>> hardware support is available. Linux is planned to have WebGPU support in >>>>> the future, so this feature will become available when WebGPU does. >>>>> >>>>> >>>>> >>>>> >>>>> *Is this feature fully tested by web-platform-tests >>>>> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?* >>>>> >>>>> Yes >>>>> >>>>> WebGPU/WGSL have a conformance test suite ( >>>>> https://github.com/gpuweb/cts) that is regularly pulled into Chromium >>>>> and part of the testing of Dawn/Tint in Chromium. While the CTS can be >>>>> embedded in WPT, the WebGPU team opted to keep it separate in Chromium >>>>> testing to use a customized harness for robustness and performance. All >>>>> the >>>>> tests about this feature in WebGPU CTS can be found through the below >>>>> link: >>>>> https://github.com/gpuweb/cts/issues/3773 >>>>> >>>>> >>>>> >>>>> >>>>> *Flag name on chrome://flags* >>>>> >>>>> None >>>>> >>>>> >>>>> *Finch feature name* >>>>> >>>>> WebGPU.Enabled:UnsafeFeatures >>>>> >>>>> >>>>> *Requires code in //chrome?* >>>>> >>>>> False >>>>> >>>>> >>>>> *Tracking bug* >>>>> >>>>> https://issues.chromium.org/issues/358408571 >>>>> >>>>> >>>>> *Estimated milestones* >>>>> >>>>> No milestones specified >>>>> >>>>> >>>>> >>>>> >>>>> *Link to entry on the Chrome Platform Status* >>>>> >>>>> https://chromestatus.com/feature/5141929256550400 >>>>> >>>>> This intent message was generated by Chrome Platform Status >>>>> <https://chromestatus.com/>. >>>>> >>>>> >>>>> >>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "blink-dev" group. >>>>> >>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to blink-dev+...@chromium.org. >>>>> >>>> >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/DM4PR11MB623701939A127A3BA2309335ED682%40DM4PR11MB6237.namprd11.prod.outlook.com >>>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/DM4PR11MB623701939A127A3BA2309335ED682%40DM4PR11MB6237.namprd11.prod.outlook.com?utm_medium=email&utm_source=footer> >>>>> . >>>>> >>>> -- >> You received this message because you are subscribed to the Google Groups >> "blink-dev" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to blink-dev+unsubscr...@chromium.org. >> To view this discussion on the web visit >> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6e10c833-c870-4070-939a-b53b4c764c6an%40chromium.org >> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/6e10c833-c870-4070-939a-b53b4c764c6an%40chromium.org?utm_medium=email&utm_source=footer> >> . >> > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to blink-dev+unsubscr...@chromium.org. To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAA44PQgh7zt741aE4fc%3DbkHibqwrLoiZd6Pv0fnDnU-sUs73-Q%40mail.gmail.com.
