Editing Source (game engine) (section)

==== Hammer Editor ====
{{Redirect|Valve Hammer|the repair tool|Valve hammer}}

The Hammer Editor, the engine's official [[level editor]], uses rendering and compiling tools included in the SDK to create maps using the [[binary space partitioning]] (BSP) method. Level geometry is created with 3D polygons called [[Brush (video games)|brushes]]; each face can be assigned a [[Texture mapping|texture]] which also defines the properties of the surface such as the sounds used for footsteps.<ref>{{cite magazine |title=Building Crown, part two: layout design, textures, and the Hammer editor |url=https://www.pcgamer.com/building-crown-part-two-layout-design-textures-and-the-hammer-editor/ |magazine=[[PC Gamer]] |access-date=September 24, 2021 |language=en |date=March 18, 2014}}</ref> Faces can also be converted into a displacement allowing for more natural shapes such as hills to be created.

Scenery objects or complex geometry can be imported as separate 3D models from the game directory. These models can also be used as physics objects or interactive props. The editor also features an in-depth logic [[Input/output|I/O]] system that can be used to create complex interactive elements. Signals to trigger different responses or change the state of an entity can be sent between entities such as buttons, [[Non-player character|NPCs]], intangible trigger brushes, and map props.