[Vanilla Level Editing] Lesson 9: Simple Moving Sectors

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THE CORRIDOR

Overall, the corridor provides a long, curving connection between the bottom of the lift and the outer arena, as you have already seen. The intention now is to develop that area into something more than simply a long tube from one place to another. Its curving form will be used to limit the distance that players can see ahead; and variations in floor height will be introduced to make the player unsure as to whether the area is leading them further down in level or back up. (This, combined with the curving nature of the corridor, is a good way of disorienting even those players with good spatial sense. And disorienting players is a good way of making them nervous!)

Sudden and erratic changes in corridor width, combined with the general shift in direction, will also be used. These things add to the disorienting nature of the corridor, but also provide nooks and crannies in which to hide various things and keep the players distracted.

THE PUZZLE

One section of the corridor — termed the sunken section throughout this description — will be set with its floor much lower than the next section. It will be set so low, in fact, that further progress will be barred until a way has been found to raise this floor. A floor mover will be used here, of course, activated from a suitable switch.

THE TRAP

The arena beyond this corridor area will contain a heavy concentration of enemies. It will start sealed off from the corridor by a door. After opening this door, and seeing what is beyond, players may wish to retreat back into the corridor for a time! The benefit to be gained from this maneuver will be limited here by two aspects of the current development. First, the door will be made to stay open, so any monsters spotting the player will be free to follow him down the corridor. Second, a ceiling trap will be sprung to close the corridor against retreat. The player will not be forced into springing this trap, though — merely encouraged. Two switches will be provided at the door end of the corridor: one will open the door, the other will spring the trap. The first time this area is played, it’s a fairly safe bet that the ceiling will be lowered.

ADDITIONAL SWITCHES

This area will also be used to provide the switch that opens the additional room off the blood pool that was added in the previous Sortie. The implementation shown also provides another switch alcove for later use.

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IMPLEMENTING THE CHANGES

The development of this lower area requires the existing walls to be broken into quite a few new sections, and the long corridor divided up into appropriate sectors. The exact forms and shapes of these are not important, although there are a number of aspects of the development that will work better visually if certain sizes are used.

First, the various alcoves all use switch textures that are 64 pixels wide. These will sit best if the alcoves are made exactly 64 units wide. Secondly, the ceiling trap uses MARBFAC_ textures in various locations: on the outside wall of its sector, and on the face that closes off the long northern corridor after the trap has been sprung. These textures are 128 pixels wide and, again, will look best if used on correctly sized lines.

Additionally, the lighting level in this sector will be elevated relative to adjacent sectors. The wall section opposite the marble face will be made to look as though it is the source of illumination. To produce the right effect visually, this wall section should be quite short, and parallel to the wall opposite. Because of the textures used, it will also need to be split into three sections, in order to give a sensible border to the central (bright) texture — I’ll give details of that later.

The following table gives the sector settings for each of the areas in this development, working along the corridor from the bottom of the lift, around towards the arena door. Also given in this table is a column of Y-offset values. These are the vertical texture alignment values that are required to maintain the correct alignment of lines facing into the sectors that use GSTONE1 (or a derivative) anywhere on them.

This texture is used almost exclusively on the walls of this area. All of the GSTONE_ textures need careful alignment (the vertical brick spacing is not constant up these textures) if the walls are not to look odd from sector to sector—especially with as many variations as this area contains. When you come to implement this area, you should check the table to see whether a Y-offset is specified. If it is, this offset should be applied everywhere that a GSTONE texture faces into the sector (which means most of the lines, I’m afraid).



DEM1_5 is used on all floors and ceilings.

Additional implementation details of each of these sectors are given in the same order in the following section.

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LONG SOUTH CORRIDOR, WITH SWITCH ALCOVES

Each of the switch alcoves just beyond the lift use SW1HOT as the texture for their rear walls, with the lower unpegged flags set. Their side walls also have this flag set. The one on the northern side of the corridor is tagged to the secret room adjacent to the blood pool above the lift, with a special attribute of 103 (S1 Door Open Stay). The other alcove currently provides no switching action. The lines between the corridor and these alcoves should have GSTONE1 (unpegged) on their upper essentials, with the Y-offset appropriate for the sector into which they face.

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SOUTHWEST CORNER SECTION

This sector has a lower essential where it borders with the previous corridor section to its east; NUKE24 is used here. GSTONE1 is used on the essential upper texture, with its upper unpegged flag set and an appropriate Y-offset.

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SUNKEN CORRIDOR SECTION

Extra embellishments have been added to the sunken area of the corridor by adding protruding sections of wall. The faces of these narrow areas carry the GSTSATYR texture for variation. Don’t make the corridor too narrow, here, will you?

GSTONE1 is used on the lower essential where this sector adjoins the next sector to its north, with the lower unpegged flag set. Tucked away in an alcove around the back of the protruding section of the eastern wall is the switch to move this sector and allow further progress down the corridor. The line separating this alcove from the sunken area has GSTONE1 on its upper and lower essentials, both unpegged. The following shows a view of this part of the corridor, showing the blockage caused by the sunken floor — the alcove switch is just visible at the right edge of the figure.

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ALCOVE OFF SUNKEN SECTOR

This alcove uses SW1GSTON on its rear wall, with its lower unpegged flag set. This line is tagged to the sunken sector with a special attribute of 18 (S1 Floor: up to next higher) to provide the switch action. The floor of the alcove sector itself provides the new level, 24 units up from the sunken sector’s current setting — sufficient to allow the remaining step up to the next sector to become feasible. Only the side walls require the Y-offset from the table.

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RAISED CORRIDOR SECTION

Wall protrusions have been added to the raised section of the corridor too. These use GSTLION on their faces. Again, don’t make the gap between them so small that players cannot pass through.

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CORNER SECTION (CEILING TRAP)

The corner sector is to act as the ceiling trap described earlier. Some warning of this trap is provided in the textures in use: the side wall on the outside of the bend uses MARBFAC3 — as already noted, this line will need to be the right length to carry it. To produce the lighting effect described earlier, the wall that is opposite the marble face needs some special treatment. It should be divided into three, with the outer sections each about 12 units long and having SUPPORT3 on them. Between them, the middle section carries SKSPINE1 with an offset to center it.

MARBLE3 is used on the upper essential between this sector and its neighbor to the southwest: a Y-offset of 32 is used to make the skulls along the bottom of this texture visible.

The change that this sector will undergo as the ceiling trap is activated produces some latent essential textures and generates some pegging requirements. The eastern face of the sector should have MARBFACE on its outward facing upper, while the southwestern face uses GSTONE1. All the side wall lines of this sector have their lower unpegged flags set to prevent them from moving when the ceiling comes down.

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REMAINING CORRIDOR SECTIONS

The sections of the corridor leading east from the ceiling trap corner have little of note in them. NUKE24 is used on all essential lower textures here, with GSTONE1 on any uppers. Upper textures are generally unpegged and need the Y-offset appropriate to their sector.

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SWITCH ALCOVES

The pair of switch alcoves by the bottom step out of the long corridor use SW1GSTON on their rear walls. These textures have their lower unpegged flags set, as do all of the alcoves’ side walls, which use the ubiquitous GSTONE1. The northern of these alcoves has its rear wall tagged to the corner section of the corridor, with a special attribute of 41 (S1 Ceiling Lower to Floor) — it is here that the ceiling trap is activated. The MARBLE3 texture is used as the upper essential over this alcove, with its upper unpegged flag set, as a visual warning (not that many players will notice it!).

The southern alcove is tagged to the door sector at the eastern end of this corridor, with a special attribute of 103 (S1 Door Open Stay). This opens the door, allowing the player into the arena — or allowing whatever is out there into the corridor!

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THE DOOR TO THE ARENA

Finally, the door sector at the end of this corridor uses BIGDOOR7 on both faces, and DOORTRAK on its side walls, with the lower unpegged flag set, as is usual for doors.

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TRYING THE MODIFICATIONS

That completes the modifications to the corridor beyond the lift. If you have implemented these changes, you may like to try the WAD out and see how well it works. You may discover that, as it stands, the WAD contains a number of nasty traps for the player — some of which were not intended and which need rectification.

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A WORD ABOUT TRAPS

Few people doubt the need for traps in a WAD. They add a mental challenge to the game, making players keep an eye open for things other than the obvious and providing them with something more than an exercise in grabbing the goodies and shooting the monsters. However, it is easy to have traps backfire on you as a designer, and turn what seemed a nice idea at the time into a major irritation that detracts from play rather than contributes to it.

Consider, for example, the ceiling trap that has just been added to the WAD. Its main aim is to cut off the line of retreat down the corridor, forcing the player to face whatever is out in the arena once the next door is opened. In this sense, this trap works well. It has some unfortunate side effects, however.

First, it makes it necessary for the player to find another way out of the arena, this exit being closed. Now, you made another way out earlier: the lift up to the window of the platform room. This works fine — provided that the window was previously opened! If not, the player is trapped here for good.

Second, it is just possible for a fast player to make it back under the closing ceiling. Any players doing this gain nothing, however, for the ceiling will still close and will now deny them access to the arena (and whatever it contains). The game will need to be restarted before the arena can be entered — an annoyance, to say the least.

The important lesson to learn here is that traps need to be examined carefully for all possible ramifications. Remember that not everyone plays in the same way — what may seem to you a logical way of proceeding through a WAD may never occur to other players. As a designer, you need to foresee every action that your players may attempt and consider all possible sequences in which these actions will be carried out.

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KEEPING TRAPS UNDER CONTROL

The key to the successful management of traps is to plan around the WAD as a whole, not around the traps you fancy using. Do not be seduced by neat traps and tricks. Consider rather what constraints you want to put on the players, and implement traps to bring these about.

Remember, too, that traps limit a player’s options. You should use them only to force players into taking particular paths that you want them to go down. If you force them down too rigid a pathway, prescribing their play in too great a detail, you prevent players from finding their own solutions. The result is bored players.

In planning your areas for particular playing methodologies, always allow for others. Only use traps if you want to close off particular (easy) options. The traps contained in the WAD developed in the Sorties so far have been added with little regard for the playability of the WAD as a whole; they have largely been illustrative of the techniques. And this has made the WAD a bit of a mess.

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EXAMINING THE PROBLEM HERE

Let us look at the details of the current predicament, starting with the window. The intention in having this area closed at the start of the game was to make the opening of the window a surprise for the player climbing towards the platform — just one more thing to worry about while busy dealing with whatever the platform room contains.

If the player decides to pass straight through the platform room and the subsequent corridors down to the arena below, though, that surprise is no longer needed. There is therefore nothing to be lost by enabling this window to be opened from its arena side if it is still closed when the player reaches it. You may wish to enable the player to do this manually — locating the switch could be a further puzzle here — or have it happen automatically by using suitably placed trips (on the approach to or exit from the arena lift, for example).

Second, look at the ceiling trap. As already noted, the purpose of this trap is to force the player who trips it to face whatever lies ahead. There is no good reason to have this prevent him from returning along this corridor later, once the arena has been cleared. You may wish to provide a switch somewhere in the arena to open this section of corridor again from there. (Something to bear in mind when that area comes to be developed.) More immediately useful, perhaps, would be the provision of some means of opening it from its other side, just in case a player makes it back there.

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REPAIRING THE WAD

You should, therefore, make some minor repairs to your WAD, to correct the current glut of traps. Start by adding some mechanism to open the platform room’s northern window from the arena side. Then, allow the lower corridor’s corner section to be opened from its southwestern side in the event that a player returns here after the ceiling trap has been sprung. A standard manual door action on this section would allow any player back through this blockage, but would still have it close again in case the arena monsters hadn’t been dealt with!

Save your final, corrected WAD as D2WAD19A.WAD to stay in step with my WAD numbering.

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CRUSHERS

The floor and ceiling movements that have been examined so far have all been delayed (or temporarily reversed) by players or monsters who become caught up in their actions. No harm is done to players or monsters when this happens. There are two categories of actions that work very differently: the crushing floors and the crushing ceilings.

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CRUSHING FLOORS

DOOM’s crushing floors operate by moving up to 8 units below their sector’s ceiling, catching anything that is in the sector and crushing it. The crushing action does considerable harm to whatever is caught in the action and is usually fatal for players and smaller monsters. Barrels caught in the action will explode, adding their quota of damage to anything nearby.

A floor crusher’s motion continues to completion even when things are caught in it; anything thus caught is quickly pinned to the ceiling. Monsters not killed are unable to move or fight. The floor travels at standard mover speed, so players will need to shift rapidly to escape the pinning action.

Other sector actions can be applied after this action is complete, although a bug in the game engine prevents further floor or ceiling movements if anything remains trapped and alive in the crusher.

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CRUSHING CEILINGS

DOOM’s crushing ceilings operate somewhat differently from the crushing floors. Whereas the floors move once, from their starting position to just below the ceiling, the crushing ceilings, once activated, continue to operate, cycling between their starting height and 8 units above their sector’s floor. They become what are termed perpetual movers. The next section examines perpetual movers in detail.

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PERPETUAL MOVERS

Most of the actions initiated by lines’ special attributes operate for a finite time only. Once they terminate, the actions are deemed to be over and the affected sectors are free to participate in further actions. Perpetual mover actions do not function like this. Their actions never terminate.

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PERPETUAL ACTIONS

It is important to realize that it is not the movement that these actions initiate, which is perpetual, but the action. This means that DOOM regards these actions as ongoing for the rest of the game, even if the movement has been stopped. Perpetual movers are therefore never free to participate in any other sector-changing action (except adjustments to the lighting levels, which always occur whether or not other activities are taking place).

The action is deemed never to finish because the motions that these special lines trigger are cyclic in nature and therefore without logical termination. Additional special line types are provided to stop the motions of perpetual movers, but they only pause the action. Any further triggering of this action will cause the mover to continue in its original cycle of movement, starting up again from where it was paused.

Perpetually moving platforms do, of course contribute to the count of surfaces in motion, and continue making noise indefinitely. It is a sensible idea, therefore, to make sure that you include lines in your map to suspend their motion as the player moves away from them. If you want to give the player the impression that their motion is indeed continuous, you can always arrange multiple on/off tripwire arrangements, as were used for the lights in the previous room.

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PERPETUAL CRUSHERS

The crushing ceilings are all classed as perpetual crushers. They begin their cycle of movement by moving downwards from their starting height. This initial height is the uppermost limit of their travel. The lower limit of their travel is 8 units above their sector floor.

Crushing ceilings operate at two speeds: fast and slow. The fast crushers move at the same speed as standard lifts and doors, while the slow crushers move at the speed of a mover. With one exception, they all make the standard mover sound. The exception is the new crusher introduced in DOOM v1.666: the so-called silent crusher. This is a fast crusher, which is silent during its travel. It does makes a clunk sound as it starts to move, though, and at each end of its travel.

The fast crushers continue in their motion regardless of whether anything is caught in them or not; slow crushers, on the other hand, reduce their speed of descent drastically when something is caught in them, reverting to the normal speed as the motion reverses. As both types of crusher hold on to anything so caught, inflicting harm for as long as it takes them to move from the object’s height to their lower limit of travel and back, slow crushers will do considerably more damage per crush than will fast crushers.

As perpetual movers, sectors that are started as crushers never become free to participate in any subsequent action that might try to affect their floor or ceiling. All of the start/resume triggers will operate on these sectors, however, causing the crushing motion to resume, even if they are triggers for a different type of crushing action. The action that resumes is always of the original type.

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PERPETUAL LIFTS

The other type of perpetual mover is the continuously operating lift. Once activated, this lift operates by moving its floor continuously up and down from one extreme of its travel to the other, moving at about half the speed of standard lifts. There is a three–second pause as the direction of travel reverses. These lifts make the same sound as ordinary lifts as they start, reverse, and stop their motions.

A perpetual lift obtains both extremes of its motion from adjacent sectors (or its own starting floor level, if this is beyond either of these extremes). The range over which the lift operates is calculated once, at the point when the perpetual motion is first initiated. From then on, the action operates over this range regardless of whether adjacent sectors’ floors subsequently move.

The initial direction of travel is determined by the lift’s starting location within its range of motion: The lift always starts by heading away from the closest extreme of travel. If initiated when positioned exactly in the middle, it starts by moving up. If positioned anywhere other than at the lower extreme, motion begins immediately after the action is initiated. If started while at its lower extreme, the lift will pause for three seconds (its usual turn–round period) before moving.

Like any perpetual mover, if the action is paused, any retrigger of the action will cause the lift to resume the motion that was under way when it was interrupted. This means the lift will operate over its full range, as before, irrespective of any changes that may have taken place around it.

Like standard lifts, these lifts automatically reverse their travel if players or monsters become caught between their floors and its own or adjacent ceilings. This causes no harm to players or monsters.

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WAD SORTIE 20: ADDING A CRUSHER

This Sortie will concentrate on the addition of a single crusher.

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A SETTING FOR THE CRUSHER

The new crusher is to be located in a new area south of the southern courtyard, in a corridor linking the secret room with the sniper’s den.

New sectors making the connection between the two existing areas will provide:

• Another hidden door, shot-activated
  
• A short corridor
  
• A perpetual crushing ceiling
  
• A longer corridor
  
• A further door
  

In addition, a recess will be needed beyond the door just inside the sniper’s den.

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ADDING THE NEW AREA

The secret room and/or the sniper’s den may need extending or reshaping a little to allow convenient connection of the new areas, which should be drawn using WOOD3 as the default wall texture.





In addition, make sure that BROWN96 remains on the outer surface of the sniper’s wall. It will now be needed on an additional texture slot here and have its upper and lower unpegged flags set to allow for the changes to the sector behind it.

Make the western door an impact-activated door, in the usual way. Make the eastern door capable of being opened from the corridor side only. Have it latch open, once activated.

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BUILDING THE CRUSHER

To implement the crusher itself, use the inner surface of the new area’s western door to start the motion: this line should be tagged to the crushing sector with a special attribute of 73 (WR Crusher Start with Slow Damage). Remember that you should make sure that perpetual movers are turned off as players leave this area. Use line-type 74 (WR Crusher Stop) on suitable lines to achieve this. Remember also that you will need to cover both halves of the new area to allow for players leaving by either route. I suggest using the sniper’s wall itself, and one of the lines in the southwestern courtyard recess. Any one of these lines that is not currently active will do, provided that it is not so close to a spacebar-activated trigger that it will stop that trigger from working.

Finally, save this WAD as D2WAD20.WAD and try out this latest area. Of course, you’ll have to get in there first.

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EXIT: MOPPING UP AND MOVING ON

In this room you encountered several more types of active sectors: lifts; simple moving floors and ceilings; and crushers. You have been shown how each of these operates and how to construct them in your own WADs.

The next room contains yet more active sectors and shows you how to manage complex active-sector arrangements.