The Orange Box engine branch was released in 2007 with the Orange Box (Ep2, Portal, TF2). It is currently being maintained side-by-side with the Left 4 Dead branch; the two branches share technology, but it is unclear if they will ever be merged or if one will come to be favoured.
The OB builds on the original HL2 branch, requiring its content installed to work.
New since the Episode One branch is:
- Logic and rendering have been threaded for performance gains in multi-core environments.
- Soft particles
- An all-new, artist-driven particle system.
- Shadow mapping
- A modern dynamic lighting and shadowing technology. See env_projectedtexture.
- Alpha to coverage
- Vector-like edges to raster images, fast. See $distancealpha.
- Automatic displacement texturing
- Avoids ugly stretching. See $seamless_scale.
- DirectX 9.8
- DX9 running on DX10 hardware. Benefits are unclear.
- Xbox 360 support
- Of no use to modders, needless to say!
Gamecode for this branch is included in the Source SDK.