# Objective
- Add 1-bounce RT GI
## Solution
- Implement a very very basic version of ReSTIR GI
https://d1qx31qr3h6wln.cloudfront.net/publications/ReSTIR%20GI.pdf
- Pretty much a copy of the ReSTIR DI code, but adjusted for GI.
- Didn't implement add more spatial samples, or do anything needed for
better quality.
- Didn't try to improve perf at all yet (it's actually faster than DI
though, unfortunately 😅)
- Didn't spend any time cleaning up the shared abstractions between
DI/GI
---
## Showcase
<img width="2564" height="1500" alt="image"
src="https://github.com/user-attachments/assets/1ff7be1c-7d7d-4e53-8aa6-bcec1553db3f"
/>
# Objective
- Notice a word duplication typo
- Small quest to fix similar or nearby typos with my faithful companion
`\b(\w+)\s+\1\b`
## Solution
Fix em
# Bevy Solari
<img
src="https://github.com/user-attachments/assets/94061fc8-01cf-4208-b72a-8eecad610d76"
width="100" />
## Preface
- See release notes.
- Please talk to me in #rendering-dev on discord or open a github
discussion if you have questions about the long term plan, and keep
discussion in this PR limited to the contents of the PR :)
## Connections
- Works towards #639, #16408.
- Spawned https://github.com/bevyengine/bevy/issues/18993.
- Need to fix RT stuff in naga_oil first
https://github.com/bevyengine/naga_oil/pull/116.
## This PR
After nearly two years, I've revived the raytraced lighting effort I
first started in https://github.com/bevyengine/bevy/pull/10000.
Unlike that PR, which has realtime techniques, I've limited this PR to:
* `RaytracingScenePlugin` - BLAS and TLAS building, geometry and texture
binding, sampling functions.
* `PathtracingPlugin` - A non-realtime path tracer intended to serve as
a testbed and reference.
## What's implemented?
* BLAS building on mesh load
* Emissive lights
* Directional lights with soft shadows
* Diffuse (lambert, not Bevy's diffuse BRDF) and emissive materials
* A reference path tracer with:
* Antialiasing
* Direct light sampling (next event estimation) with 0/1 MIS weights
* Importance-sampled BRDF bounces
* Russian roulette
## What's _not_ implemented?
* Anything realtime, including a real-time denoiser
* Integration with Bevy's rasterized gbuffer
* Specular materials
* Non-opaque geometry
* Any sort of CPU or GPU optimizations
* BLAS compaction, proper bindless, and further RT APIs are things that
we need wgpu to add
* PointLights, SpotLights, or skyboxes / environment lighting
* Support for materials other than StandardMaterial (and only a subset
of properties are supported)
* Skinned/morphed or otherwise animating/deformed meshes
* Mipmaps
* Adaptive self-intersection ray bias
* A good way for developers to detect whether the user's GPU supports RT
or not, and fallback to baked lighting.
* Documentation and actual finalized APIs (literally everything is
subject to change)
## End-user Usage
* Have a GPU that supports RT with inline ray queries
* Add `SolariPlugin` to your app
* Ensure any `Mesh` asset you want to use for raytracing has
`enable_raytracing: true` (defaults to true), and that it uses the
standard uncompressed position/normal/uv_0/tangent vertex attribute set,
triangle list topology, and 32-bit indices.
* If you don't want to build a BLAS and use the mesh for RT, set
enable_raytracing to false.
* Add the `RaytracingMesh3d` component to your entity (separate from
`Mesh3d` or `MeshletMesh3d`).
## Testing
- Did you test these changes? If so, how?
- Ran the solari example.
- Are there any parts that need more testing?
- Other test scenes probably. Normal mapping would be good to test.
- How can other people (reviewers) test your changes? Is there anything
specific they need to know?
- See the solari.rs example for how to setup raytracing.
- If relevant, what platforms did you test these changes on, and are
there any important ones you can't test?
- Windows 11, NVIDIA RTX 3080.
---------
Co-authored-by: atlv <email@atlasdostal.com>
Co-authored-by: IceSentry <IceSentry@users.noreply.github.com>
Co-authored-by: Carter Anderson <mcanders1@gmail.com>
