BModel

BModel (bsp model) or submodel, mapobject model is a model constructed in level editor out of brushes or patches and compiled into the .bsp file. Doors, trains, platforms are bmodels.

BModel could be internal (supplied with the level and have special names such as *1, *2, *3 etc.) and external (BSP files). External BSP model differs from level file, it usually have no VIS data, entities, and other level-specific data.

Benefits

• very fast to render
• automatically get collisions
• supplied with level .bsp's (no external files)
• easy to construct in level editor (dont need a third party tools)
• can be lightmapped or lit dynamically (using lightgrid)
• can have triangle models attached

Drawbacks

• cannot be animated (only moved/rotated)
• badly optimized mesh (since it automatically generated from CSG)
• complex models with lots of corners or curved surfaces is not that easy to make