Archived from the original dev blog and left as it was written, so it reflects the game as it stood in 2008.
As all Mappers know players are tricky people, they have ways of finding things in your map and doing stuff you never intended. Map exploits are always found by that one player and every time the Mapper has to release a fix to solve the problem that’s ruining the map or rely on Admins to deal with the players who abuse it. A little bit of fore thought and player control helps prevent this problem.
The player clip textures is one of the Mapper’s best friends when it comes to player control and also conversely the players best friend when it comes to map flow, let me show you with a shot of the crossbow nest in bounce (of course the shot is non final).
As you can see there is clearly a large amount of player clipping going on in the area, some of it to stop the player from doing what I don’t want and some of it to stop the player from getting hung up. The clip above the wall is because the player is not meant to get up there and the cliff is to be shear. The sloped brushes above the objects are so the player cannot jump on top, or if he is falling that he falls to the ground itself. If the clips were not there players could climb the wall and get to unwanted places. The ledges would not be physically wide enough to support a human; however, as any ledge can support a player in game its up to the Mapper to enforce it. On the same token if the player plans to move in a direction, the player shouldn’t be stopped from doing so unless there’s a wall directly in front of them, a common situation is detailed below.
The green player is running down the side of the hall when the red object appears in front of him, the player plans to back away to deal with it. In the first picture there are no clips and so the player gets stuck on the pillars in the hall, this stops the player’s movement and more often than not kills him causing him to dislike the experience. In the second shot we add some clips that simply bump the player round the detail, the player keeps moving the way he intended and feels no animosity towards the game or its designers. For that purpose the rest of the clips were added onto the sides of the objects, clips to allow the player to brush past the door without getting stuck on its frame or its button, clips to hide the complex prop indented in the wall so the player can keep flush to the wall. While it may not be an issue the 10x you play the 1 instance where it is will leave that sour taste in your mouth regarding the area.
Spending time to analyze how a player might move round the map and adding in clips to ensure the players movement will be smooth is often overlooked by the Mapper themselves as it never directly concerns them, but it’s one of the touches that make your level more enjoyable and should be considered by all that want the player to enjoy their work every time they play it.