pathTrace

The GPU side of the reference view: two compute passes and a blit, enqueued only while referenceView is enabled.

Pass	Order	What it does
pt_trace	10	One thread per pixel. Builds a primary ray from the camera in the parameter block, follows it through the scene BVH, and adds the radiance into the accumulation buffer. Skipped once the image has converged.
pt_resolve	11	Divides the accumulation by the sample count it carries in alpha, exposes, tonemaps, and writes the display image.
blit	12	Draws that image over the scene colour.

All three run at afterLighting, where the scene colour is fully lit on both render paths — the state the reference is meant to be compared against.

The resolved target is created at a fixed size rather than with screen = true: the accumulation buffer is indexed by that resolution, and an engine-driven resize per render target would silently invalidate every sample in it. The blit scales the image to whatever target it lands in.

The scene arrives entirely through buffers the module snapshotted, so this runs on either backend with no dependency on hardware ray tracing or on the deferred G-buffer.