N14: Diffuse GI (#295)

* Added section on diffuse gi

* Changed phrase sound a bit better

* N14: diffgl: Smaller GIF

* N14: diffgi: Style & fmt tweaks

Co-authored-by: Andrey Lesnikov <[email protected]>

Author: miolad

content/posts/newsletter-014/diff-gi.gif

@@ -421,6 +421,32 @@ The source code [can be found here][bevy-flappy-src].
 [bevy-flappy-video]: https://youtube.com/watch?v=Qjc0V58lB7A
 [bevy-flappy-src]: https://github.com/TanTanDev/flappy_bevy
 
+### [Real-Time Global Illumination in WGPU][gi-post]
+
+[![diff-gi-gif](diff-gi.gif)][gi-post]
+_Infinite light bounces in Cornell Box_
+
+[DI2edd] shared his [real-time diffuse global illumination demo on /r/rust_gamedev][gi-post].
+It's written in 100% Rust and uses WGPU for graphics, proving that the API
+is an excellent choice even for advanced computer graphics applications.
+
+The technique provides real time global illumination for static lambertian
+geometry, and is the implementation of the 2017 paper ["Real-time Global
+Illumination by Precomputed Local Reconstruction
+from Sparse Radiance Probes"](https://arisilvennoinen.github.io/Projects/RTGI/index.html),
+which proposes a spherical harmonics-based approach to solve the rendering equation
+in real time.
+
+In practice, this means that the expensive light transport calculations are performed
+in a precomputation step, which relies on - among others - [embree-rs],
+and [nalgebra] to produce a compressed
+representation of the scene that is then used for lighting reconstruction at runtime.
+
+[gi-post]: https://reddit.com/r/rust_gamedev/comments/ixocl2/real_time_diffuse_global_illumination
+[DI2edd]: https://reddit.com/u/DI2edd
+[embree-rs]: https://github.com/Twinklebear/embree-rs
+[nalgebra]: https://github.com/dimforge/nalgebra
+
 ## Library & Tooling Updates
 
 ### [Thunderdome]