# MBF21 Specification v1.4

MBF21 supports the full spec of boom & mbf, plus the following.

## Generalized Sector Types

| Dec  | Bit | Description            |
|------|-----|------------------------|
| 4096 | 12  | Alternate damage mode  |
| 8192 | 13  | Kill grounded monsters |

#### Alternate damage mode

The meaning of the damage bits changes when the alternate damage mode bit is set.

| Dec | Bit 6-5 | Description                                                   |
|-----|---------|---------------------------------------------------------------|
| 0   | 00      | Kills a player unless they have a rad suit or invulnerability |
| 32  | 01      | Kills a player                                                |
| 64  | 10      | Kills all players and exits the map (normal exit)             |
| 96  | 11      | Kills all players and exits the map (secret exit)             |

## Linedef Flags

| Dec  | Bit | Description          |
|------|-----|----------------------|
| 4096 | 12  | Block land monsters  |
| 8192 | 13  | Block players        |

## Linedef Types

#### Line scroll special variants

From the boom spec, type 255 is defined like so:

> 255    -- Scroll Wall Using Sidedef Offsets                   
>
> For simplicity, a static scroller is provided that scrolls the first sidedef of a linedef, based on its x- and y- offsets. No tag is used. The x offset controls the rate of horizontal scrolling, 1 unit per frame per x offset, and the y offset controls the rate of vertical scrolling, 1 unit per frame per y offset.

MBF21 has 3 types which operate like type 255, but also apply the scroll to all other linedefs which share the same tag. Additionally, the scrolling speed is divided by 8 in order to give more fine-grained control.

- 1024 is the standard scroller.
- 1025 is the displacement scroller variant.
- 1026 is the accelerative scroller variant.

To use in a map, set the special on a control linedef, set its x and y offsets as desired to set the scroll speed, assign it a tag, and set the same tag on any destination linedefs to apply the scroll. The x and y offsets of destination linedefs do not factor into the scroll speed, so it's possible to do proper texture alignment.

The displacement scroller, as defined in the boom spec:

> In the first kind, displacement scrolling, the position of the scrolled objects or walls changes proportionally to the motion of the floor or ceiling in the sector on the first sidedef of the scrolling trigger. The proportionality is set by the length of the linedef trigger. If it is 32 units long, the wall, floor, ceiling, or object moves 1 unit for each unit the floor or ceiling of the controlling sector moves. If it is 64 long, they move 2 units per unit of relative floor/ceiling motion in the controlling sector and so on.

The accelerative scroller, as defined in the boom spec:

> The second kind of dynamic scrollers, accelerative scrollers, also react to height changes in the sector on the first sidedef of the linedef trigger, but the RATE of scrolling changes, not the displacement. That is, changing the controlling sector's height speeds up or slows down the scrolling by the change in height times the trigger's length, divided by 32.

## Things

#### Dehacked Thing Groups

##### Infighting
- Add `Infighting group = N` in Thing definition.
- `N` is a nonnegative integer.
- Things with the same value of `N` will not target each other after taking damage.

##### Projectile
- Add `Projectile group = M` in Thing definition.
- `M` is an integer.
- Things with the same value of `M` will not deal projectile damage to each other.
- A negative value of `M` means that species has no projectile immunity, even to other things in the same species.

##### Splash
- Add `Splash group = S` in Thing definition.
- `S` is a nonnegative integer.
- If an explosion (or other splash damage source) has the same splash group as the target, it will not deal damage.

##### Examples
```
Thing 12 (Imp)
Projectile group = -1
Splash group = 0

Thing 16 (Baron of Hell)
Projectile group = 2

Thing 18 (Hell Knight)
Infighting group = 1
Projectile group = 1

Thing 21 (Arachnotron)
Infighting group = 1
Projectile group = 2

Thing 31 (Barrel)
Splash group = 0
```

In this example:
- Imp projectiles now damage other Imps (and they will infight with their own kind).
- Barons and Arachnotrons are in the same projectile group: their projectiles will no longer damage each other.
- Barons and Hell Knights are not in the same projectile group: their projectiles will now damage each other, leading to infighting.
- Hell Knights and Arachnotrons are in the same infighting group: they will not infight with each other, despite taking damage from each other's projectiles.
- Imps and Barrels are in the same splash group: barrels no longer deal splash damage to imps.
- Note that the group numbers are separate - being in infighting group 1 doesn't mean you are in projectile group 1.

#### New Thing Flags
- Add `MBF21 Bits = X` in the Thing definition.
- The format is the same as the existing `Bits` field.
- Example: `MBF21 Bits = LOGRAV+DMGIGNORED+MAP07BOSS1`.
- The value can also be given as a number (sum of the individual flag values below).

| Flag           | Value   | Description                                                                                    |
|----------------|---------|------------------------------------------------------------------------------------------------|
| LOGRAV         | 0x00001 | Lower gravity (1/8)                                                                            |
| SHORTMRANGE    | 0x00002 | Short missile range (archvile)                                                                 |
| DMGIGNORED     | 0x00004 | Other things ignore its attacks (archvile)                                                     |
| NORADIUSDMG    | 0x00008 | Doesn't take splash damage (cyberdemon, mastermind)                                            |
| FORCERADIUSDMG | 0x00010 | Thing causes splash damage even if the target shouldn't                                        |
| HIGHERMPROB    | 0x00020 | Higher missile attack probability (cyberdemon)                                                 |
| RANGEHALF      | 0x00040 | Use half distance for missile attack probability (cyberdemon, mastermind, revenant, lost soul) |
| NOTHRESHOLD    | 0x00080 | Has no targeting threshold (archvile)                                                          |
| LONGMELEE      | 0x00100 | Has long melee range (revenant)                                                                |
| BOSS           | 0x00200 | Full volume see / death sound & splash immunity (from heretic)                                 |
| MAP07BOSS1     | 0x00400 | Tag 666 "boss" on doom 2 map 7 (mancubus)                                                      |
| MAP07BOSS2     | 0x00800 | Tag 667 "boss" on doom 2 map 7 (arachnotron)                                                   |
| E1M8BOSS       | 0x01000 | E1M8 boss (baron)                                                                              |
| E2M8BOSS       | 0x02000 | E2M8 boss (cyberdemon)                                                                         |
| E3M8BOSS       | 0x04000 | E3M8 boss (mastermind)                                                                         |
| E4M6BOSS       | 0x08000 | E4M6 boss (cyberdemon)                                                                         |
| E4M8BOSS       | 0x10000 | E4M8 boss (mastermind)                                                                         |
| RIP            | 0x20000 | Ripper projectile (does not disappear on impact)                                               |
| FULLVOLSOUNDS  | 0x40000 | Full volume see / death sounds (cyberdemon, mastermind)                                        |

#### Rip sound
- When set, this is the sound that plays for ripper projectiles when they rip through something.
- Add `Rip sound = X` in the Thing definition.
- `X` is the sound index, as seen in other sound fields.

#### Fast speed
- Sets the thing speed for skill 5 / -fast.
- Add `Fast speed = X` in the Thing definition.
- `X` has the same units as the normal `Speed` field.

#### Melee range
- Sets the range at which a monster will initiate a melee attack.
- Also affects the range for vanilla melee attack codepointers, e.g. A_SargAttack, A_TroopAttack, etc.
  - Similarly, adjusting the player mobj's melee range will adjust the range of A_Punch and A_Saw
- Add `Melee range = X` in the Thing definition.
- `X` is in fixed point, like the Radius and Height fields

## Weapons

#### Weapon Flags
- Add `MBF21 Bits = X` in the Weapon definition.
- The format is the same as the existing thing `Bits` field.
- Example: `MBF21 Bits = SILENT+NOAUTOFIRE`.
- The value can also be given as a number (sum of the individual flag values below).

| Name           | Value | Description                                      |
|----------------|-------|--------------------------------------------------|
| NOTHRUST       | 0x001 | Doesn't thrust things                            |
| SILENT         | 0x002 | Weapon is silent                                 |
| NOAUTOFIRE     | 0x004 | Weapon won't autofire when swapped to            |
| FLEEMELEE      | 0x008 | Monsters consider it a melee weapon              |
| AUTOSWITCHFROM | 0x010 | Can be switched away from when ammo is picked up |
| NOAUTOSWITCHTO | 0x020 | Cannot be switched to when ammo is picked up     |

MBF21 defaults:

| Weapon          | Flags                                   |
|-----------------|-----------------------------------------|
| Fist            | FLEEMELEE+AUTOSWITCHFROM+NOAUTOSWITCHTO |
| Pistol          | AUTOSWITCHFROM                          |
| Shotgun         |                                         |
| Chaingun        |                                         |
| Rocket Launcher | NOAUTOFIRE                              |
| Plasma Rifle    |                                         |
| BFG             | NOAUTOFIRE                              |
| Chainsaw        | NOTHRUST+FLEEMELEE+NOAUTOSWITCHTO       |
| Super Shotgun   |                                         |

#### Ammo pickup weapon autoswitch changes
- Weapon autoswitch on ammo pickup now accounts for the ammo per shot of a weapon, as well as the `NOAUTOSWITCHTO` and `AUTOSWITCHFROM` weapon flags, allowing more accuracy and customization of this behaviour.
- If the current weapon is enabled for `AUTOSWITCHFROM` and the player picks up ammo for a different weapon, autoswitch will occur for the highest ranking weapon (by index) matching these conditions:
  - player has the weapon
  - weapon is not flagged with `NOAUTOSWITCHTO`
  - weapon uses the ammo that was picked up
  - player did not have enough ammo to fire the weapon before
  - player now has enough ammo to fire the weapon

#### New DEHACKED "Ammo per shot" Weapon field
- Add `Ammo per shot = X` in the Weapon definition.
- Value must be a nonnegative integer.
- Tools should assume this value is undefined for all vanilla weapons (i.e. always write it to the patch if the user specifies any valid value)
- Weapons WITH this field set will use the ammo-per-shot value when:
  - Checking if there is enough ammo before firing
  - Determining if the weapon has ammo during weapon auto-switch
  - Deciding how much ammo to subtract in native Doom weapon attack pointers
    - Exceptions: A_Saw and A_Punch will never attempt to subtract ammo.
  - The `amount` param is zero for certain new MBF21 DEHACKED codepointers (see below).
- Weapons WITHOUT this field set will use vanilla Doom semantics for all above behaviors.
- For backwards-compatibility, setting the `BFG cells/shot` misc field will also set the BFG weapon's `Ammo per shot` field (but not vice-versa).

## Frames

#### Frame Flags
- Add `MBF21 Bits = X` in the Frame definition.
- The format is the same as the existing thing `Bits` field.
- Example: `MBF21 Bits = SKILL5FAST`.
- The value can also be given as a number (sum of the individual flag values below).

| Name       | Value | Description                           |
|------------|-------|---------------------------------------|
| SKILL5FAST | 0x001 | Tics halve on nightmare skill (demon) |

#### New "Args" fields for DEHACKED states
- Defines 8 new integer fields in the state table for use as codepointer arguments
- Args are defined in dehacked by adding `Args1 = X`, `Args2 = X`... up to `Args8 = X` in the State definition.
- Default value for each arg is determined by the frame's codepointer. See docs below.
- For future-proofing, if args are defined on a state than its action pointer expects (e.g. defining Args3 on a state that uses A_WeaponSound), an error must be thrown on startup.

#### New DEHACKED Codepointers
- All new MBF21 pointers use the new "Args" fields for params, rather than misc1/misc2 fields
- Arg fields are listed in order in the docs below, e.g. for `A_SpawnObject`, `type` is Args1, `angle` is Args2, etc.
- Although all args are integers internally, there are effectively the following types of args:
  - `int`: An integer. 'Nuff said.
  - `uint`: An unsigned integer. Must be greater than or equal to zero.
  - `fixed` A [fixed-point](https://doomwiki.org/wiki/Fixed_point) number.
    - For user-friendliness, a suggested convention for MBF21-supporting DEHACKED tools is to convert numbers with decimal points to their fixed-point representation when saving the patch (e.g. "1.0" gets saved as "65536"), so this doesn't get super-ugly on the user side of life.

##### Actor pointers

- **A_SpawnObject(type, angle, x_ofs, y_ofs, z_ofs, x_vel, y_vel, z_vel)**
  - Generic actor spawn function.
  - Args:
    - `type (uint)`: Type (dehnum) of actor to spawn
    - `angle (fixed)`: Angle (degrees), relative to calling actor's angle
    - `x_ofs (fixed)`: X (forward/back) spawn position offset
    - `y_ofs (fixed)`: Y (left/right) spawn position offset
    - `z_ofs (fixed)`: Z (up/down) spawn position offset
    - `x_vel (fixed)`: X (forward/back) velocity
    - `y_vel (fixed)`: Y (left/right) velocity
    - `z_vel (fixed)`: Z (up/down) velocity
  - Notes:
    - If the spawnee is a missile, the `tracer` and `target` pointers are set as follows:
      - If spawner is also a missile, `tracer` and `target` are copied to spawnee
      - Otherwise, spawnee's `target` is set to the spawner and `tracer` is set to the spawner's `target`.

- **A_MonsterProjectile(type, angle, pitch, hoffset, voffset)**
  - Generic monster projectile attack.
  - Args:
    - `type (uint)`: Type (dehnum) of actor to spawn
    - `angle (fixed)`: Angle (degrees), relative to calling actor's angle
    - `pitch (fixed)`: Pitch (degrees), relative to calling actor's pitch
    - `hoffset (fixed)`: Horizontal spawn offset, relative to calling actor's angle
    - `voffset (fixed)`: Vertical spawn offset, relative to actor's default projectile fire height
  - Notes:
    - The spawned projectile's `tracer` pointer is always set to the spawner's `target`, for generic seeker missile support.

- **A_MonsterBulletAttack(hspread, vspread, numbullets, damagebase, damagedice)**
  - Generic monster bullet attack.
  - Args:
    - `hspread (fixed)`: Horizontal spread (degrees, in fixed point)
    - `vspread (fixed)`: Vertical spread (degrees, in fixed point)
    - `numbullets (uint)`: Number of bullets to fire; if not set, defaults to 1
    - `damagebase (uint)`: Base damage of attack; if not set, defaults to 3
    - `damagedice (uint)`: Attack damage random multiplier; if not set, defaults to 5
  - Notes:
    - Damage formula is: `damage = (damagebase * random(1, damagedice))`
    - Damage arg defaults are identical to Doom's monster bullet attack damage values.

- **A_MonsterMeleeAttack(damagebase, damagedice, sound, range)**
  - Generic monster melee attack.
  - Args:
    - `damagebase (uint)`: Base damage of attack; if not set, defaults to 3
    - `damagedice (uint)`: Attack damage random multiplier; if not set, defaults to 8
    - `sound (uint)`: Sound to play if attack hits
    - `range (fixed)`: Attack range; if not set, defaults to calling actor's melee range property
  - Notes:
    - Damage formula is: `damage = (damagebase * random(1, damagedice))`

- **A_RadiusDamage(damage, radius)**
  - Generic explosion.
  - Args:
    - `damage (uint)`: Max explosion damge
    - `radius (uint)`: Explosion radius, in map units

- **A_NoiseAlert**
  - Alerts monsters within sound-travel distance of the calling actor's target.
  - No Args.

- **A_HealChase(state, sound)**
  - Generic A_VileChase. Chases the player and resurrects any corpses with a Raise state when bumping into them.
  - Args:
    - `state (uint)`: State to jump to on the calling actor when resurrecting a corpse
    - `sound (uint)`: Sound to play when resurrecting a corpse

- **A_SeekTracer(threshold, maxturnangle)**
  - Generic seeker missile function.
  - Args:
    - `threshold (fixed)`: If angle to target is lower than this, missile will 'snap' directly to face the target
    - `maxturnangle (fixed)`: Maximum angle a missile will turn towards the target if angle is above the threshold
  - Notes:
    - When using this function, keep in mind that seek 'strength' also depends on how often this function is called -- e.g. calling `A_SeekTracer` every tic will result in a much more aggressive seek than calling it every 4 tics, even if the args are the same
    - This function is based on Heretic's seeker missile logic, rather than Doom's, so there are some slight differences in behavior compared to A_Tracer (better z-axis seeking, for instance).

- **A_FindTracer(fov, rangeblocks)**
  - Searches for a valid tracer (seek target), if the calling actor doesn't already have one. Particularly useful for player missiles.
  - Args:
    - `fov (fixed)`: Field-of-view, relative to calling actor's angle, to search for targets in. If zero, the search will occur in all directions.
    - `rangeblocks (uint)`: Distance to search, in map blocks (128 units); if not set, defaults to 10.
  - Notes:
    - Setting the `rangeblocks` arg too high may hurt performance, so don't get overzealous.
    - This function will no-op if the calling actor already has a tracer. To forcibly re-acquire a new tracer, call A_ClearTracer first.
    - This function will exclude any actor that is "friendly" to the shooter (e.g. players will not target friendly monsters, enemy monsters will not target each other unless infighting, and so forth).

- **A_ClearTracer**
  - Clears the calling actor's tracer (seek target) field.
  - No Args.

- **A_JumpIfHealthBelow(state, health)**
  - Jumps to a state if caller's health is below the specified threshold.
  - Args:
    - `state (uint)`: State to jump to
    - `health (int)`: Health to check
  - Notes:
    - The jump will only occur if health is BELOW the given value -- e.g. `A_JumpIfHealthBelow(420, 69)` will jump to state 420 if health is 68 or lower.

- **A_JumpIfTargetInSight(state)**
  - Jumps to a state if caller's target is in line-of-sight.
  - Args:
    - `state (uint)`: State to jump to
    - `fov (fixed)`: Field-of-view, relative to calling actor's angle, to check for target in. If zero, the check will occur in all directions.

- **A_JumpIfTargetCloser(state, distance)**
  - Jumps to a state if caller's target is closer than the specified distance.
  - Args:
    - `state (uint)`: State to jump to
    - `distance (fixed)`: Distance threshold, in map units
  - Notes:
    - The jump will only occur if distance is BELOW the given value -- e.g. `A_JumpIfTargetCloser(420, 69.0)` will jump to state 420 if distance is 68.0 or lower.

- **A_JumpIfTracerInSight(state)**
  - Jumps to a state if caller's tracer (seek target) is in line-of-sight.
  - Args:
    - `state (uint)`: State to jump to
    - `fov (fixed)`: Field-of-view, relative to calling actor's angle, to check for tracer in. If zero, the check will occur in all directions.

- **A_JumpIfTracerCloser(state, distance)**
  - Jumps to a state if caller's tracer (seek target) is closer than the specified distance.
  - Args:
    - `state (uint)`: State to jump to
    - `distance (fixed)`: Distance threshold, in map units
  - Notes:
    - The jump will only occur if distance is BELOW the given value -- e.g. `A_JumpIfTracerCloser(420, 69.0)` will jump to state 420 if distance is 68.0 or lower.

- **A_JumpIfFlagsSet(state, flags, flags2)**
  - Jumps to a state if caller has the specified thing flags set.
  - Args:
    - `state (uint)`: State to jump to.
    - `flags (int)`: Standard actor flag(s) to check
    - `flags2 (int)`: MBF21 actor flag(s) to check
  - Notes:
    - If multiple flags are specified in a field, jump will only occur if all the flags are set (e.g. AND comparison, not OR)

- **A_AddFlags(flags, flags2)**
  - Adds the specified thing flags to the caller.
  - Args:
    - `flags (int)`: Standard actor flag(s) to add
    - `flags2 (int)`: MBF21 actor flag(s) to add

- **A_RemoveFlags(flags, flags2)**
  - Removes the specified thing flags from the caller.
  - Args:
    - `flags (int)`: Standard actor flag(s) to remove
    - `flags2 (int)`: MBF21 actor flag(s) to remove

##### Weapon pointers

- **A_WeaponProjectile(type, angle, pitch, hoffset, voffset)**
  - Generic weapon projectile attack.
  - Args:
    - `type (uint)`: Type (dehnum) of actor to spawn
    - `angle (fixed)`: Angle (degrees), relative to player's angle
    - `pitch (fixed)`: Pitch (degrees), relative to player's pitch
    - `hoffset (fixed)`: Horizontal spawn offset, relative to player's angle
    - `voffset (fixed)`: Vertical spawn offset, relative to player's default projectile fire height
  - Notes:
    - Unlike native Doom attack codepointers, this function will not consume ammo, trigger the Flash state, or play a sound.
    - The spawned projectile's `tracer` pointer is set to the player's autoaim target, if available.

- **A_WeaponBulletAttack(hspread, vspread, numbullets, damagebase, damagedice)**
  - Generic weapon bullet attack.
  - Args:
    - `hspread (fixed)`: Horizontal spread (degrees, in fixed point)
    - `vspread (fixed)`: Vertical spread (degrees, in fixed point)
    - `numbullets (uint)`: Number of bullets to fire; if not set, defaults to 1
    - `damagebase (uint)`: Base damage of attack; if not set, defaults to 5
    - `damagedice (uint)`: Attack damage random multiplier; if not set, defaults to 3
  - Notes:
    - Unlike native Doom attack codepointers, this function will not consume ammo, trigger the Flash state, or play a sound.
    - Damage formula is: `damage = (damagebase * random(1, damagedice))`
    - Damage arg defaults are identical to Doom's weapon bullet attack damage values.
      - Note that these defaults are intentionally different for weapons vs monsters (5d3 vs 3d5) -- yup, Doom did it this way. :P

- **A_WeaponMeleeAttack(damagebase, damagedice, zerkfactor, sound, range)**
  - Generic weapon melee attack.
  - Args:
    - `damagebase (uint)`: Base damage of attack; if not set, defaults to 2
    - `damagedice (uint)`: Attack damage random multiplier; if not set, defaults to 10
    - `zerkfactor (fixed)`: Berserk damage multiplier; if not set, defaults to 1.0
    - `sound (uint)`: Sound index to play if attack hits
    - `range (fixed)`: Attack range; if not set, defaults to player mobj's melee range property
  - Notes:
    - Damage formula is: `damage = (damagebase * random(1, damagedice))`; this is then multiplied by `zerkfactor` if the player has Berserk.

- **A_WeaponSound(sound, fullvol)**
  - Generic playsound for weapons.
  - Args:
    - `sound (uint)`: Sound index to play.
    - `fullvol (int)`: If nonzero, play this sound at full volume across the entire map.

- **A_WeaponJump(state, chance)**
  - Random state jump for weapons.
  - Args:
    - `state (uint)`: State index to jump to.
    - `chance (int)`: Chance out of 256 to perform the jump. 0 (or below) never jumps, 256 (or higher) always jumps.

- **A_ConsumeAmmo(amount)**
  - Subtracts ammo from the currently-selected weapon's ammo pool.
  - Args:
    - `amount (int)`: Amount of ammo to subtract. If zero, will default to the current weapon's `ammopershot` value.
  - Notes:
    - This function will not reduce ammo below zero.
    - If `amount` is negative, ammo will be added to the ammo pool instead.

- **A_CheckAmmo(state, amount)**
  - Jumps to `state` if ammo is below `amount`.
  - Args:
    - `state (uint)`: State index to jump to.
    - `amount (uint)`: Amount of ammo to check. If zero, will default to the current weapon's `ammopershot` value.
  - Notes:
    - The jump will only occur if ammo is BELOW the given value -- e.g. `A_CheckAmmo(420, 69)` will jump to state 420 if ammo is 68 or lower.

- **A_RefireTo(state, noammocheck)**
  - Jumps to `state` if the fire button is currently being pressed and the weapon has enough ammo to fire.
  - Args:
    - `state (uint)`: State index to jump to.
    - `noammocheck (int)`: If nonzero, skip the ammo check.

- **A_GunFlashTo(state, nothirdperson)**
  - Generic weapon muzzle flash.
  - Args:
    - `state (uint)`: State index to set the flash psprite to.
    - `nothirdperson (int)`: If nonzero, do not change the 3rd-person player sprite to the player muzzleflash state.

- **A_WeaponAlert**
  - Alerts monsters within sound-travel distance of the player's presence. Useful for weapons with the WPF_SILENT flag set.
  - No Args.

## Miscellaneous

#### New comp flags
- comp_ledgeblock:
  - Ledges block ground enemies (default)
  - Exception: movement due to scrolling / pushers / pullers disables comp_ledgeblock for the next xy movement
- comp_friendlyspawn:
  - When on (default): A_Spawn new thing inherits friend flag from source thing.
  - When off: A_Spawn new thing keeps its default friend flag.
- comp_voodooscroller:
  - When on: voodoo dolls on slow scrollers move too slowly
  - When off (default): voodoo dolls move the same speed as the floor
- comp_reservedlineflag:
  - When on: the line flag 0x0800 clears extended flags.
  - When off: the line flag 0x0800 means nothing.

#### Option default changes
- comp_pursuit: 1 (was 0)
  - This means the mbf infighting cooldown is disabled by default.

#### Fixes / adjustments since mbf
- Fix 3 key door bug
- Fix generalized crusher walkover lines
- Fix blockmap issue seen in btsx e2 Map 20
- Fix negative ammo counts
- Fix weapon autoswitch not taking DEHACKED ammotype changes into account