The three main types of entities

Once you are familiar with sculpting your environment you will want to start to turn it into a more playable world. To do so you need to put in entities. An entity is completely different to a brush. Entities are broken down into three types:

• Brush entities.
• Point entities.
• Node entities.

When creating multiplayer maps you will only use the Brush and Point. But in all single player maps you will use nodes.

A brush entity is one that is tied to a brush that you have created. You can change how it looks and effects the environment. They do not appear in the New Objects toolbar. Brush entities can also be used to trigger an event; such as triggering an attack by the combine. In a lot of cases brush entities are a crucial part in an event. Examples of brush entities are; Func_door, Func_movelinear, Trigger_once.

Point entities are ones that make the map come alive, they can be broken down further:

• Logic entities. These affect the gameplay but except for lighting all other logic entities cannot be seen.
• Prop entities. Are models, some of them can have AI. There are three types of prop entities: Static, Dynamic and Physics.
• NPC Entities. These are Non playable Characters, such as the combine and striders.

Prop and NPC entities are represented in the game as models.

A node is a hint/clue that gives an NPC information on what is around them. It gives them useful information on locations to go. Such as; a wall to hide behind and shoot, a window to look into and see if the player is hiding.