oriented-bbox-not-set-on-rdna4
Status: stub. The full-length analysis is queued for a v1.0.x patch release per ADR 0018, section 5, criterion #6. The companion rule page at docs/rules/oriented-bbox-not-set-on-rdna4.md contains the canonical detection logic + GPU reasoning.
TL;DR
Per Chips and Cheese's RDNA 4 raytracing deep-dive, RDNA 4 gains up to 10% RT performance when the BLAS is built with the D3D12_RAYTRACING_GEOMETRY_FLAG_USE_ORIENTED_BOUNDING_BOX (or VK equivalent) flag. The flag is project-side state -- we cannot inspect it from shader source -- so the rule emits a one-time-per-source informational note pointing the developer to verify their BLAS-build code.
What the rule fires on
A defensive informational rule. Fires once per source that contains any RT call (TraceRay, RayQuery::Proceed, TraceRayInline) under the [experimental.target = rdna4] config gate.
See the What it detects section of the rule page for the full pattern definition.
Why it matters
The full GPU-mechanism analysis lives in the Why it matters on a GPU section of the companion rule page.
Examples
The bad / good code snippets are kept canonical on the rule page; see oriented-bbox-not-set-on-rdna4.md -> Examples.
See also
- Rule page -- canonical reference + change log.
- rdna4 overview -- broader context.
- ADR 0018 -- v1.0 readiness plan.
This is a v1.0-ship stub. Full analysis pending; track issue link TBD.
TODO: category-overview missing for rdna4; linked overview is the closest sibling.