A few versions ago, wgpu made it possible to set shader entry point to
`None`, which will select the correct entry point in file where only a
single entrypoint is specified. This makes it possible to implement
`Default` for pipeline descriptors. This PR does so and attempts to
`..default()` everything possible.
# Objective
- This unblocks some work I am doing for #19887.
## Solution
- Rename `RenderGraphApp` to `RenderGraphExt`.
- Implement `RenderGraphExt` for `World`.
- Change `SubApp` and `App` to call the `World` impl.
Some misc cleanup in preparation for future PRs.
* Merge reservoir.wgsl with restir_di.wgsl, as the reservoir is going to
be DI-specific and won't be reused for GI
* Reformulate confidence weights to not multiply by INITIAL_SAMPLES. The
multiplication cancels out, it doesn't matter.
# Objective
- Start the realtime direct lighting work for bevy solari
## Solution
- Setup all the CPU-side code for the realtime lighting path (minus some
parts for the temporal reuse I haven't written yet)
- Implement RIS with 32 samples to choose a good random light
- Don't sample a disk for the directional light, just treat it as a
single point. This is faster and not much worse quality.
## Future
- Spatiotemporal reuse (ReSTIR DI)
- Denoiser (DLSS-RR)
- Light tile optimization for faster light selection
- Indirect lighting (ReSTIR GI)
## Testing
- Run the solari example to see realtime
- Run the solari example with `-- --pathtracer` to see the existing
pathtracer
---
## Showcase
1 frame direct lighting:
Accumulated pathtracer output:
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Co-authored-by: Alice Cecile <alice.i.cecile@gmail.com>
