Brushes are templates used in some 3D video

game engine A game engine is a software framework primarily designed for the development of video games and generally includes relevant libraries and support programs. The "engine" terminology is similar to the term "software engine" used in the software i ...

s, such as the

Quake engine The ''Quake'' engine is the game engine developed by id Software to power their 1996 video game '' Quake''. It featured true 3D real-time rendering and is now licensed under the terms of GNU General Public License v2.0 or later. After releas ...

, its derivatives the

GoldSrc GoldSrc ( ) is a proprietary game engine developed by Valve. At its core, GoldSrc is a heavily modified version of id Software's ''Quake'' engine. It originally made its debut in 1998 with ''Half-Life'', and would power future games developed b ...

and

Source game engine Source is a 3D game engine developed by Valve. It debuted as the successor to GoldSrc in 2004 with the release of '' Counter-Strike: Source'' and ''Half-Life 2''. Updates to Source were released in incremental versions, with the engine being suc ...

s, or the

Unreal Engine Unreal Engine (UE) is a 3D computer graphics game engine developed by Epic Games, first showcased in the 1998 first-person shooter game ''Unreal''. Initially developed for PC first-person shooters, it has since been used in a variety of genres ...

, to construct

levels Level or levels may refer to: Engineering *Level (instrument), a device used to measure true horizontal or relative heights *Spirit level, an instrument designed to indicate whether a surface is horizontal or vertical *Canal pound or level *Regr ...

. Brushes can be primitive shapes (such as cubes, spheres and cones), pre-defined shapes (such as staircases), or custom shapes (such as prisms and other

polyhedra In geometry, a polyhedron (plural polyhedra or polyhedrons; ) is a three-dimensional shape with flat polygonal faces, straight edges and sharp corners or vertices. A convex polyhedron is the convex hull of finitely many points, not all on t ...

). During the map compilation process, brushes are turned into meshes that can be rendered by the game engine. Often brushes are restricted to convex shapes only, as this reduces the complexity of the

binary space partitioning In computer science, binary space partitioning (BSP) is a method for space partitioning which recursively subdivides a Euclidean space into two convex sets by using hyperplanes as partitions. This process of subdividing gives rise to a represent ...

process. However, using CSG operations, complex rooms and objects can be created by adding, subtracting and intersecting brushes to and from one another. Additionally, brushes can be used as liquids or as an area trigger.BSP Headquarters - BSP Quake Tutorial #6
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References

Video game development {{videogame-software-stub