Implement #776: Level script - fixed alliances

[IntelOrca]

Resolves #776

Used the last 3 unused bits in player->allied_players to represent which allies (blue, green, yellow) are locked. This means that this functionality is currently limited to single player.

Changes to ALLY_PLAYERS:

• Unlocked enemy: ALLY_PLAYERS(PLAYER1,PLAYER2,0)
• Unlocked ally: ALLY_PLAYERS(PLAYER1,PLAYER2,1)
• Locked enemy: ALLY_PLAYERS(PLAYER1,PLAYER2,2)
• Locked ally: ALLY_PLAYERS(PLAYER1,PLAYER2,3)

New command: IF_ALLIED({PLAYER},{PLAYER}{OP}{VALUE}):
Allows you to check the ally status of any two players. This will allow all sorts of use cases, such as forming a reply alliance in single player, or special events in multiplayer if two particular players are allied.

Example script:
Add this to the end of Korros Tor (levels\deepdngn\map00081.txt) or any other 2 player map.

ALLY_PLAYERS(PLAYER0,PLAYER1,1)
IF_ALLIED(PLAYER0,PLAYER1==0)
    QUICK_OBJECTIVE(1,"Blue will not accept this betrayal, prepare for battle.",PLAYER1)

    REM no going back now, lock as enemies
    ALLY_PLAYERS(PLAYER0,PLAYER1,2)
ENDIF
IF_ALLIED(PLAYER0,PLAYER2==1)
    IF_ALLIED(PLAYER0,PLAYER1==1)
        QUICK_OBJECTIVE(2,"Blue will not accept your alliance with Green, prepare for battle.",PLAYER1)
        REM lock blue as enemy
        ALLY_PLAYERS(PLAYER0,PLAYER1,2)
    ENDIF

    REM lock green as ally
    ALLY_PLAYERS(PLAYER0,PLAYER2,3)
ENDIF

Allying with green causes the player to automatically win the level. I am not exactly sure why, since I would have thought the unally with blue would execute first, before the ally with green command. I guess there is something about the way scripts are executed which I don't quite understand.

[PieterVdc]

well multiplayer and campaigns where the player isn't red, I guess we could also look if one of the many unnamed fields might just be unused by the game, and have the locked stuff in there instead

[Loobinex]

Allying with blue with that script triggered victory because it checked against the ALL_DUNGEONS_DESTROYED var for victory, which ignores allies.

[eddebaby]

For my own sake really...
ALLY_PLAYERS works like this:

• set PLAYER2 as enemy of PLAYER1 (remove PLAYER2 from PLAYER1's ally list) and unlock PLAYER2 in PLAYER1's ally/enemy list:
  ALLY_PLAYERS(PLAYER1,PLAYER2,0)
• set PLAYER2 as ally of PLAYER1 (add PLAYER2 to PLAYER1's ally list) and unlock PLAYER2 in PLAYER1's ally/enemy list:
  ALLY_PLAYERS(PLAYER1,PLAYER2,1)
• set PLAYER2 as enemy of PLAYER1 (remove PLAYER2 from PLAYER1's ally list) and lock PLAYER2 in PLAYER1's ally/enemy list:
  ALLY_PLAYERS(PLAYER1,PLAYER2,2)
• set PLAYER2 as ally of PLAYER1(add PLAYER2 to PLAYER1's ally list) and lock PLAYER2 in PLAYER1's ally/enemy list:
  ALLY_PLAYERS(PLAYER1,PLAYER2,3)