Penumbra

Penumbra is Meridian’s renderer above the hardware interface. It owns how renderable snapshots become measured frames. It does not own the authoritative world or hand unrestricted backend access to game code.

Frame flow

1. 01World snapshot

   Extraction selects stable, render-relevant state at an explicit barrier.

2. 02Upload

   Meridian-owned descriptors become bounded GPU resources behind the RHI.

3. 03Render graph

   Pass dependencies, lifetimes, and timing are made explicit.

4. 04Penumbra passes

   The current direct PBR path produces a frame and typed pass evidence.

5. 05Surface outcome

   Presented, offscreen, unavailable, or failed outcomes stay distinguishable.

Current foundation

The public snapshot contains a wgpu-backed RHI behind Meridian contracts, a render graph, direct PBR, cascaded shadows, diffuse irradiance IBL, extraction and upload, typed pass timing, asynchronous capture, and bounded structural and native GPU smokes.

That is real rendering implementation. It is not the complete production renderer, final image quality, or a benchmark claim.

Production direction

Clustered Forward+ is the adopted production shading path. Shared render graph, GPU scene, material and shader IR, visibility, streaming, lighting, temporal, profiling, and resource systems are meant to remain path-independent.

Specular environment IBL, broader environmental rendering, calibrated quality evidence, and native backend work remain later packages at this revision.

Boundary to remember

An offscreen capture proves that bytes were produced through a bounded path. It does not prove that a user saw a production-quality frame on every target platform.