Thanks for this, Brandon. As you know, the collateral we need to go first is much higher than when closing compatibility gaps.
This explainer doesn't indicate why anyone needs the feature, show the before/after state of example code, or discuss considered alternatives. I'm inclined to support the feature, but can't without more to go on. Can you produce and updated explainer with the various things we usually expect to see? Best, Alex On Wednesday, August 27, 2025 at 7:17:40 PM UTC+1 Brandon Jones wrote: > Apologies! We're currently trying to decide where docs like that should > live after we move them out of experimental status. In the meantime you can > see the historical copy of the explainer here: > https://dawn.googlesource.com/dawn/+/2819d509eff7e314e5ebce15cc3a7cb13370a505/docs/tint/extensions/chromium_experimental_primitive_id.md > > (Note that at the time the explainer was written the feature was going to > be named primitive_id, the rename to primitive_index was a relatively late > change by the working group.) > > --Brandon > > On Wed, Aug 27, 2025 at 1:02 AM Daniel Bratell <bratel...@gmail.com> > wrote: > >> The Explainer link is a 404 or has restricted access. We need the >> explainer to be public. >> >> /Daniel >> On 2025-08-25 10:56, Yoav Weiss (@Shopify) wrote: >> >> Can you request reviews for security/privacy/etc in chromestatus? >> >> On Fri, Aug 22, 2025 at 10:16 PM Chromestatus < >> ad...@cr-status.appspotmail.com> wrote: >> >>> Contact emails bajo...@chromium.org >>> >>> Explainer >>> https://dawn.googlesource.com/dawn/+/refs/heads/main/docs/tint/extensions/chromium_experimental_primitive_id.md >>> >>> >>> Specification >>> https://gpuweb.github.io/gpuweb/#dom-gpufeaturename-primitive-index >>> >>> Summary >>> >>> This feature adds a new optional capability to WebGPU that exposes a new >>> WGSL shader builtin, 'primitive_index'. This builtin provides a >>> per-primitive index to fragment shaders on supported hardware, similar to >>> the existing vertex_index and instance_index builtins. The primitive index >>> is useful for advanced graphical techniques, such as virtualized geometry. >>> >>> >>> Blink component Blink>WebGPU >>> <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EWebGPU%22> >>> >>> >>> Search tags webgpu <http:///features#tags:webgpu>, primitive >>> <http:///features#tags:primitive> >>> >>> TAG review None >>> >>> TAG review status Pending >>> >>> Risks >>> >>> >>> Interoperability and Compatibility >>> >>> Little to none. It's a fairly minor feature that all implementors have >>> voiced support for. The feature is optional and support for it must be >>> explicitly queried through the standard WebGPU supported features >>> mechanism. Some hardware doesn't expose it yet, so developers need to >>> structure their apps to have a fallback path anyway. >>> >>> >>> *Gecko*: No signal >>> >>> *WebKit*: No signal >>> >>> *Web developers*: No signals >>> >>> *Other signals*: >>> >>> Ergonomics >>> >>> None. >>> >>> >>> Activation >>> >>> None. >>> >>> >>> Security >>> >>> None. >>> >>> >>> 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 >>> >>> >>> Debuggability >>> >>> WGSL shader feature. Shaders generally lack debugging support in >>> browsers. >>> >>> >>> Will this feature be supported on all six Blink platforms (Windows, Mac, >>> Linux, ChromeOS, Android, and Android WebView)? Yes >>> >>> Feature is widely supported and has equivalents in all Native APIs that >>> WebGPU is implemented on top of. Some older hardware lacks ability to >>> report the value, which is why it's an optional feature. >>> >>> >>> Is this feature fully tested by web-platform-tests >>> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md> >>> ? No >>> >>> WebGPU CTS tests are a WIP: https://github.com/gpuweb/cts/pull/4435 >>> >>> >>> Flag name on about://flags enable-unsafe-webgpu >>> >>> Finch feature name None >>> >>> Non-finch justification None >>> >>> Rollout plan Will ship enabled for all users >>> >>> Requires code in //chrome? False >>> >>> Tracking bug https://issues.chromium.org/issues/342172182 >>> >>> Estimated milestones >>> >>> No milestones specified >>> >>> >>> Anticipated spec changes >>> >>> Open questions about a feature may be a source of future web compat or >>> interop issues. Please list open issues (e.g. links to known github issues >>> in the project for the feature specification) whose resolution may >>> introduce web compat/interop risk (e.g., changing to naming or structure of >>> the API in a non-backward-compatible way). >>> None >>> >>> Link to entry on the Chrome Platform Status >>> https://chromestatus.com/feature/6467722716250112?gate=4665168428662784 >>> >>> 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+unsubscr...@chromium.org. >>> To view this discussion visit >>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/68a8d032.050a0220.8fac8.a218.GAE%40google.com >>> >>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/68a8d032.050a0220.8fac8.a218.GAE%40google.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 visit >> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOmohS%2BP74WaABq%2BdYeukKDUvBazGrTk7SnT5QLRj09ZZwrE1w%40mail.gmail.com >> >> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOmohS%2BP74WaABq%2BdYeukKDUvBazGrTk7SnT5QLRj09ZZwrE1w%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> >> -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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