Architecture

Chapter contract

The wide-angle map: how a request becomes pixels, which modules own which phase, and the non-negotiable invariants. Deep module chapters hang off this spine.

Conceptual dual pipeline — Plate ARCH-C1
Conceptual illustration — not engine output Teaching sketch of two formations on one spine.

End-to-end request path

Typical example binary

Parse CLI (model path, spp, mode, denoise)
Construct Scene; load assets into actors/components
VulkanRenderer(w,h).initialize() — full GPU cold start (Ch. 03)
setScene(scene) — upload meshes, materials, lights, BLAS/TLAS
Place camera; optional env map
setRenderMode(Deferred | RTOffline | …) — RT modes call ensureRTRenderer lazily
Loop or single shot: render()
Read getPixels() / write PNG / present GLFW
Optional: denoise offline still via OIDN path inside PT

Nothing in that list requires an editor. The engine is a library with a fat GPU core.

Mode matrix

Mode	Who draws	AS?	Readback
Forward	Legacy raster	no	staging
Deferred	DeferredRenderer graph	optional hybrid	staging
RTRealtime	PathTracer (PCG, few bounces)	required	staging + denoise opts
RTOffline	PathTracer (Sobol, OIDN path)	required	HDR accum → beauty

Invariants (break these → silent wrong pixels)

Must hold across modulesalways

One scene language for deferred and PT (materials, lights, transforms)
TLAS instance order locked to material table order
Bindless indices valid or 0xFFFFFFFF “no texture”
NRD packing uses YCoCg + norm hit-dist when NRD is on
Frame ring: never read staging without waiting on that slot’s fence
PathTracer profiles lazy — do not dual-allocate at 4K

Layer cake

Layer	Owns	Deep chapter
Scene	Actors, components, loaders, physics world handle	02
GPU host	Device, upload, AS, ring, dispatch	03
Materials language	PBR + pack	04
Deferred formation	GBuffer → light → post	05
PT formation	Integrator + AOVs	06–07
Hybrid inject	RT shadow/GI into deferred	08
Denoise	OIDN/NRD/DLSS contracts	09
Audio / Physics	Sim & sound facades	10–11