[andrewmcwatters]

The renderer in Source is one of the places I don’t have a great understanding of. Quake’s is fairly straightforward, but the shader system Source has complicates understanding a lot more than if you had licensee access.

The way they talk to entities to handoff determining visibility is fantastic, and there are a number of other small design details that make the engine very pleasant to work with as a modder or game developer—but there are some things that are rather hard as an engine developer working with Source, or black boxes because no one has public information of how particular systems work anymore.

Even internally at Valve they’ve broken particular portions of Source and the Half-Life codebases because they don’t understand how particular interfaces work anymore, but some older members of the hlcoders community still do.