Hook scripts are specially named scripts that are run by sfall at specific points to allow mods to override normally hardcoded behaviour in a more flexible way than sfall's normal ini configuration.
In addition to the bit of code it overrides, the script will be run once when first loaded and again at each player reload to allow for setup. Hook scripts have access to a set of arguments supplied to sfall, but aren't required to use them all. They also return one or more values, but again they're optional, and you only need to return a value if you want to override the default.
As good practise to aid in mod compatibility, only use the hs_xxx .int script if you are setting return values. For any other scripts, use a normal global script combined with register_hook or register_hook_proc.
There are script functions specific to hook scripts:
int init_hook()
The hook script equivilent of game_loaded; it returns 2 when the script is first loaded, 1 when the player reloads and 0 otherwise.
mixed get_sfall_arg()
Gets the next argument from sfall. Each time it's called it returns the next argument, or otherwise it returns 0 if there are no more arguments left.
int get_sfall_args()
Returns all hook arguments as a new temp array.
void set_sfall_return(int value)
Used to return the new values from the script. Each time it's called it sets the next value, or if you've already set all return values it does nothing.
void set_sfall_arg(int argnum, int value)
Changes argument value. This is usefull if you have several hook scripts attached to one hook point (see below).
void register_hook(int hooktype)
Used from a normal global script if you want to run it at the same point a full hook script would normally run. In case of this function, "start" proc will be execuded in a current global script. You can use all above functions like normal.
The same as register_hook, except that you specifically define which procedure in the current script should be called as a hook (instead of "start"). Pass procedure the same as how you use dialog option functions. This IS the recommended way to use hook scripts, as it gives both modularity (each mod logic in a separate global script, no conflicts if you don't use "hs_*.int" scripts) and flexibility (you can place all related hook scripts for specific mod in a single script!).
NOTE: you can hook several scripts to a single hook point, for example if it's different mods from different authors or just some different aspects of one larger mod. In this case scripts are executed in reverse order of how they were registered. When one of the scripts in a chain returns value with "set_sfall_return", the next script may override this value if calls "set_sfall_return" again. Sometimes you need to multiply certain value in a chain of hook scripts.
Mod B also want to affect hit chances globally, by increasing them by 50%. Now in order for both mods to work well together, we need to add this line to Mod A hook script:
set_sfall_arg(original_chance / 2);
This basically changes hook argument for the next script. Mod B code:
So if you combine both mods together, they will run in chain and the end result will be a 75% from original hit chance (hook register order doesn't matter in this case, if you use "set_sfall_arg" in both hooks).
The defines to use for the hooktype are in sfall.h.
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----------- HOOK SCRIPT TYPES -------------
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hs_tohit.int
Runs when fallout is calculating the chances of an attack striking a target
Runs after the hit chance is fully calculated normally, including applying the 95% cap
int arg1 - The unmodified hit chance
critter arg2 - The attacker
critter arg3 - The target of the attack
int arg4 - The targeted bodypart
int ret1 - the new hit chance
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hs_afterhitroll.int
Runs after fallout has decided if an attack will hit or miss
int arg1 - If the attack will hit. (0 - critical miss, 1 - miss, 2 - hit, 3 - critical hit)
critter arg2 - The attacker
critter arg3 - The target of the attack
int arg4 - The bodypart
int arg5 - The hit chance
int ret1 - Override the hit/miss
int ret2 - Override the targeted bodypart
critter ret3 - Override the target of the attack
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hs_calcapcost.int
Runs whenever fallout is calculating the ap cost of using the weapon (or unarmed attack). Doesn't run for using other item types or moving.
Note that the first time a game is loaded, this script doesn't run before the initial interface is drawn, so if the script effects the ap cost of whatever is in the players hands at the time the wrong ap cost will be shown. It will be fixed the next time the interface is redrawn.
You can get the weapon object by checking item slot based on attack type (ATKTYPE_LWEP1, ATKTYPE_LWEP2, etc) and then calling critter_inven_obj().
critter arg1 - The critter performing the action
int arg2 - Attack Type (see ATKTYPE_* constants)
int arg3 - Is aimed attack (1 or 0)
int arg4 - The normal ap cost
int ret1 - The new ap cost
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hs_deathanim1.int
Runs before fallout tries to calculate the death animation. Lets you switch out which weapon fallout sees
int arg1 - The pid of the weapon performing the attack. (May be -1 if the attack is unarmed)
critter arg2 - The attacker
critter arg3 - The target
int arg4 - The amount of damage
int ret1 - The pid of an object to override the attacking weapon with
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hs_deathanim2.int
Runs after fallout has calculated the death animation. Lets you set your own custom frame id, so more powerful than hs_deathanim1, but performs no validation.
When using critter_dmg function, this script will also run. In that case weapon pid will be -1 and target will point to an object with obj_art_fid == 0x20001F5.
item arg1 - The pid of the weapon performing the attack. (May be -1 if the attack is unarmed)
critter arg2 - The attacker
critter arg3 - The target
int arg4 - The amount of damage
int arg5 - The death anim id calculated by fallout
int ret1 - The death anim id to override with
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hs_combatdamage.int
Runs when:
1) Game calculates how much damage each target will get. This includes primary target as well as all extras (explosions and bursts). This happens BEFORE the actual attack animation.
2) AI decides whether it is safe to use area attack (burst, grenades), if he might hit friendlies.
Does not run for misses, or non-combat damage like dynamite explosions.
critter arg1 - The target
critter arg2 - The attacker
int arg3 - The amount of damage to the target
int arg4 - The amount of damage to the attacker
int arg5 - The special effect flags for the target
int arg6 - The special effect flags for the attacker
int arg7 - The weapon used in the attack
int arg8 - The bodypart that was struck
int arg9 - Roll result of the attack (check with is_success, etc functions; basically: 0-crit. fail, 1-fail, 2-success, 3-crit. success)
int arg10 - Number of bullets actually hit the target (1 for melee attacks)
int arg11 - The amount of knockback to the target
int ret1 - The damage to the target
int ret2 - The damage to the attacker
int ret3 - The special effect flags for the target
int ret4 - The special effect flags for the attacker
int ret5 - The amount of knockback to the target
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hs_ondeath.int
Runs immediately after a critter dies for any reason. No return values; this is just a convinence for when you need to do something after death for a large number of different critters and don't want to have to script each and every one of them.
Critter arg1 - The critter that just died
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hs_findtarget.int
Runs when the ai is trying to pick a target in combat. Fallout first chooses a list of 4 likely suspects, then normally sorts them in order of weakness/distance/etc depending on the ai caps of the attacker. This hook replaces that sorting function, allowing you to sort the targets in some arbitrary way. Use sfall_return to give the 4 targets, in order of preference. All 4 must be given if you want to override normal sorting; if you want to specify less than 4 targets fill in the extra spaces with 0's. If you do not give 4 targets, the npcs normal sorting mechanism will be used.
The return values can include critters that weren't in the list of possible targets, but the additional targets may still be discarded later on in the combat turn if they are out of the attackers perception or the chance of a successful hit is too low. The list of possible targets often includes duplicated entries.
critter arg1 - The attacker
critter arg2 - A possible target
critter arg3 - A possible target
critter arg4 - A possible target
critter arg5 - A possible target
critter ret1 - The first choice of target
critter ret2 - The second choice of target
critter ret3 - The third choice of target
critter ret4 - The fourth choice of target
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hs_useobjon.int
Runs when:
1) a critter uses an object on another critter. (Or themselves)
2) a critter uses an object from inventory screen AND this object does not have "Use" action flag set and it's not active flare or explosive.
3) player or AI uses any drug
This is fired before the object is used, and the relevent use_obj_on script procedures are run. You can disable default item behavior.
NOTE: you can't remove and/or destroy this object during the hookscript (game will crash otherwise). To remove it, return 1.
Critter arg1 - The target
Critter arg2 - The user
int arg3 - The object used
int ret1 - overrides hard-coded handler and selects what should happen with the item (0 - place it back, 1 - remove it, -1 - use engine handler)
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hs_useobj.int
Runs when:
1) a critter uses an object from inventory which have "Use" action flag set or it's an active flare or dynamite.
2) player uses an object from main interface
This is fired before the object is used, and the relevent use_obj script procedures are run. You can disable default item behavior.
NOTE: you can't remove and/or destroy this object during the hookscript (game will crash otherwise). To remove it, return 1.
Critter arg1 - The user
int arg2 - The object used
int ret1 - overrides hard-coded handler and selects what should happen with the item (0 - place it back, 1 - remove it, -1 - use engine handler)
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hs_removeinvenobj.int
Runs when an object is removed from a critters inventory for any reason
critter arg1 - the critter the object is being removed from
item arg2 - the item that is being removed
int arg3 - a flag, or possibly the number of items to remove
int arg4 - The reason the object is being removed. (Actually, the site from which _item_remove_mult was called)
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hs_barterprice.int
Runs whenever the value of goods being purchased is calculated
critter arg1 - the critter doing the bartering (either dude_obj or inven_dude)
critter arg2 - the critter being bartered with
int arg3 - the default value of the goods
critter arg4 - the barter critter (has all of the goods being traded in its inventory)
int arg5 - the amount of actual caps in the barter stack (as opposed to goods)
int arg6 - the value of all goods being traded before skill modifications
int arg3 - key VK code (very similar to ASCII codes)
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hs_mouseclick.int
Runs once every time when a mouse button was pressed or release.
int arg1 - event type: 1 - pressed, 0 - released
int arg2 - button number (0 - left, 1 - right, up to 7)
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hs_useskill.int
Runs when using any skill on any object.
This is fired before the default handlers are called, which you can override. In this case you should write your own skill use handler entirely, or otherwise nothing will happen (this includes fade in/fade out, time lapsing and messages - all of this can be scripted; to get vanilla text messages - use message_str_game() along with sprintf()).
This is fired before the default handlers are called, which you can override. In this case you MUST provide message of the result to player ("You steal the %s", "You are caught planting the %s", etc.).
int ret1 - overrides hard-coded handler (1 - force success, 0 - force fail, -1 - use engine handler)
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hs_withinperception.int
Runs when checking if one critter sees another critter. This is used in different situations like combat AI. You can override the result.
NOTE: obj_can_see_obj calls this first when deciding if critter can possibly see another critter with regard to perception, lighting, sneak factors. If check fails, the end result is false. If check succeeds (eg. critter is within perception range), another check is made if there is any blocking tile between two critters (which includes stuff like windows, large bushes, barrels, etc.) and if there is - check still fails. You can override "within perception" check by returning 0 or 1, OR, as a convenience, you can also override blocking check after the perception check by returning 2 instead. In this case you should add "line of sight" check inside your hook script, otherwise critters will detect you through walls.
int arg3 - Result of vanilla function: 1 - within perception range, 0 - otherwise
int ret1 - overrides the returned result of the function: 0 - not in range (can't see), 1 - in range (will see if not blocked), 2 - forced detection (will see regardless, only used in obj_can_see_obj scripting function which is called by every critter in the game)
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hs_inventorymove.int
Runs before moving items between inventory slots in dude interface. You can override the action.
What you can NOT do with this hook:
- force moving items to inapropriate slots (like gun in armor slot)
- block picking up items
What you can do:
- restrict player from using specific weapons or armors
- add AP costs for all inventory movement including reloading
- apply or remove some special scripted effects depending on PC's armor
int arg1 - Target slot (0 - main backback, 1 - left hand, 2 - right hand, 3 - armor slot, 4 - weapon, when reloading it by dropping ammo)
Item arg2 - Item being moved
Item arg3 - Item being replaced or weapon being reloaded (can be 0)
int ret1 - Override setting (-1 - use engine handler, any other value - prevent relocation of item/reloading weapon)
