BRUSHES
See also: Passable Brushes - Editors - Level Design
Updated June 6, 2002 - 10:11 AM

Brushes

These are the "building blocks" of Half-Life level design. Brushes are the things you create and manipulate in an editor (e.g. WorldCraft) which represent the physical structure of the game world.

Two Types of brushes

• World brushes - plain old walls, floors, etc. - you must use these to make up the hull of your world, and you typically use them for much of the interior design as well.
• Entity brushes - special programmable brushes, e.g. -
  • doors, lifts, and other moving objects
  • friction, push, and gravity effects
  • hurt
  • invisible triggers that trigger events when touched
  • visual effects such as glass and bubbles

Links to Resources

• About Invalid Brushes by Firebinder - see also Compiler Errors

The Handy Vandal's FIRST RULE OF BRUSH DESIGN

World brushes should fit together seamlessly,
without overlap.

Let me say it again:

MAKE SURE YOUR WORLD BRUSHES
NEVER OVERLAP

Problems with overlapping brushes include:

• Extra load on compiler -- increased compile time
• Extra load on engine during game play -- game may lag
• Makes larger .BSP file
• False sense of security (you don't really know what's going on)
• Sloppy design practice -- leads to sloppy maps

Nothing is gained by overlapping brushes except convenience. In my opinion, the convenience is a bad idea -- a sloppy practice that leads to sloppy level design. (By contrast -- smart level design means knowing the location and function of every brush and entity at all times.)

Entity brushes are different: in many cases, you must use overlapping entity brushes to achieve desired effects. Even so, be aware that the brushes add load -- be economical, minimize the load.

The effect of overlapping brushes is readily visible in WorldCraft in the Filled-Polygon view. Note the jagged moire effect where the selected brush overlaps the other brush:

Creating and Manipulating Brushes

Use the same tools and techniques to manipulate all brushes:

• Resizing, Slanting, Rotating
• Copy/Cut and Paste
• Vertex manipulation - a very powerful technique, but be careful -- it's very easy to unknowingly create illegal brushes, which can cause problems with maps
• Carving - another powerful technique, but some people avoid it altogether - me, for instance ....

Textures

You set the appearance of a brush, as it will appear to players, by applying textures to the brush.

Special-Property Brushes

Certain textures cause brushes to have special properties:

• sky - brush has "far away" effect, can be made to "emit light"
• clip - blocks player motion
• origin - defines center point for certain entities (such as tanks and trains) which require an invisible "helper brush" to orient the entity within the world
• Toxic textures causes pain
• Water textures causes water effects