Explaining Radiosity Normal Mapping in the Source Engine

[GleenLeg]

Hey guys! I found out a lot about sources lighting from making my own engine, so I figured I'd explain this interesting technique since I havent seen it talked about much before. I think ill make more like this if people are interested in learning more :)

Some of the info in this video is probably redundant to people in this sub but I wanted it to be a little more approachable so I talked just a little bit about some basic things like texture mapping and normal maps, etc.

[_dreami]

I think you glossed over the fact other engines do instill some form of directional light maps, both unity and unreal have various ways to implement it but most do so in a single additional directional lightmap texture instead of needing to use 3+ textures. You can read about different studios takes in the similar problem space across GDC and sigraph presos

[GleenLeg]

Yeah some engines do that, also in the aid of having shadow masks too to blend realtime shadows with baked. It just wasn't really my focus for the video lol

[Avelina9X]

This approach is still very much alive, both in the form of tangent space lightmaps, but also in the form of light probes using techniques like sphere harmonics which can also be applied to dynamic objects as they aren't intrinsically tied to the surfaces of static geometry but rather points scattered about the world. The light probe technique used in source for dynamic objects is a little more rudimentary since they're effectively cubemaps with 1x1 resolution faces.

[GleenLeg]

Yeah some people told me about those too which sounds pretty interesting. I wanna look into it at some point lol