Foreword: This tutorial assumes that you have both Half-Life and Worldcraft 2.0, and are fairly proficient in the use of Worldcraft, in that you have completed the previous tutorials in this series.

This article covers how to use: - Clip Brushes

       Okay, first on the list is to define "clip". For those of you unfamiliar to the term, "clipping" is the act of detecting when two objects collide and CANNOT pass through one another. The box that defines the player's size in the game is called a "bounding box", and the level geometry clips against this to prevent the player from falling through the floor or walking through walls. The clipping ability of brushes is also what allows a lift to raise the player up; or tell a rocket to explode; instead of passing through a wall. There are many specific situations in a game where you may want to provide some clipping function; but you don't want a visible wall. This is what the clip brush allows us to do. Like an origin brush (see Tutorial #4), the Clip Brush is just a normal brush with the "CLIP" texture applied to all sides. Let's examine a couple of situations where you might want to use one, so that you can see the usefulness of this handy little brush.

      The first situation is something that you should probably ALWAYS use a clip brush for: pipes. Whenever you want a player to be able to walk along a pipe or other angled surface, its best to place a very thin (1 or 2 units thick) clip brush just on top of the pipe. The player will LOOK like they're walking on top of the pipe; but really they'll be walking on the clip brush. This provides a flat surface so that they can run along without slipping off one side or the other too easily, which can be VERY frustrating for players.

      Another situation involves walls and the player getting "caught up". This is ESPECIALLY IMPORTANT in multiplayer levels; where fast action means that players will again be very frustrated if they keep getting snagged on little detailed brushes. Take this wall for example:

      If the player was to run along this wall; the "pictures" on the wall would stop them. They would have to move over into the corridor, move forward a little, then move back up against the wall. That's 3 actions they have to repeat over and over- what a pain! If we place a thin clip brush in front of it instead, the player can run along up against the "smooth" clip brush and get hung up (remember that the clip brush will be invisible in the game):

      The key to remember, is that the clip brush works in all directions; so in this example above, we've actually created a NEW couple of spots where the player might get "caught" - as illustrated by these shots:

      The solution to this, is to use "wedges" or angled brushes on the end, like this:

      Lastly, remember that this can be applied to ceilings and floors, too. In HBDM1, there is a spot that the player could potentially jump off of the top of the stairs and get "stuck" against the light-fixture in the ceiling. The solution was to place an angled clip brush in front, to "deflect" the player's jump:

      

      In conclusion, the Clip Brush is a handy little thing that allows for a lot of little "polishing" to be applied to your maps; but keep in mind the following things:

1. The player should NOT notice the clip brushes... they should never feel like "air" is stopping them from moving in some way.

2. Related to #1, ALWAYS try to make your clip brushes as thin as possible, and as close to "real" brushes as possible. Just like regular brushes, clip bushes can touch or overlap "normal" brushes.

3. Clip brushes are in NO WAY related to the "clip" function in WorldCraft - the WorldCraft "clip" tool can be thought of more as a "trim" tool. It has NO effect in the game; it just slices off portions of brushes while you are editing.

4. USE SPARINGLY. There are lots of places where clip brushes are handy - but remember that they ARE there in the game, even if they aren't visible... it will NOT do your level any good to plaster them all over every surface.

As always, feel free to E-mail me if you have any questions or problems. Good luck!