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RikuTheKiller c7cb0674cc Preliminary blood refactor (#93854)
## About The Pull Request

Moves all blood handling into procs and adds ways to easily hook into
basically every basic blood behavior.

This PR is not meant to fix every single case of janky blood logic in
the game. The main point and motivation of this PR is to add hooks for
blood behaviors. This allows for way more flexibility with blood code.

I am not going to fix our 3000 instances of single-letter vars, wacky
blood transfers, etc. This is just the groundwork for future PRs to
build off of, and by itself, should do very little to change blood
behavior.

I also added a rigorous set of unit tests for verifying that all of the
basic blood volume procs work correctly.

## Why It's Good For The Game

Previously, blood was handled via directly reading/writing
[var/blood_volume]. This was INCREDIBLY inconsistent and there was no
way to hook into it. This PR makes blood handling way more consistent,
which is great for all sorts of features.
2025-11-13 11:45:36 -06:00

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///how much we multiply cooldown (deciseconds) by to get the amount of blood to remove.
///BLOOD_VOLUME_NORMAL is 560, expensive spells max out at around 60 seconds which is 600 deciseconds
///removing 9/10ths of the cooldown from that puts us at 540 deciseconds, mult by 0.5 gives 270 blood taken
///one second is worth 5 blood, roughly half of your normal amount of blood taken for a huge spell, seems fair
#define COOLDOWN_TO_BLOOD_RATIO 0.5
/**
* # splattercasting component!
*
* Component that makes casted spells cost blood from the user and dramatically lowers their cooldown.
*/
/datum/component/splattercasting
/datum/component/splattercasting/Initialize()
if(!iscarbon(parent))
return COMPONENT_INCOMPATIBLE
/datum/component/splattercasting/RegisterWithParent()
. = ..()
RegisterSignal(parent, COMSIG_SPECIES_LOSS, PROC_REF(on_species_change))
RegisterSignal(parent, COMSIG_MOB_SPELL_PROJECTILE, PROC_REF(on_spell_projectile))
RegisterSignal(parent, COMSIG_MOB_BEFORE_SPELL_CAST, PROC_REF(on_before_spell_cast))
RegisterSignal(parent, COMSIG_MOB_AFTER_SPELL_CAST, PROC_REF(on_after_spell_cast))
ADD_TRAIT(parent, TRAIT_SPLATTERCASTER, REF(src))
/datum/component/splattercasting/UnregisterFromParent()
. = ..()
UnregisterSignal(parent, list(COMSIG_SPECIES_LOSS, COMSIG_MOB_SPELL_PROJECTILE, COMSIG_MOB_BEFORE_SPELL_CAST, COMSIG_MOB_AFTER_SPELL_CAST))
REMOVE_TRAIT(parent, TRAIT_SPLATTERCASTER, REF(src))
///signal sent when a spell casts a projectile
/datum/component/splattercasting/proc/on_species_change(mob/living/carbon/source, datum/species/lost_species)
SIGNAL_HANDLER
qdel(src)
///signal sent when the parent casts a spell that has a projectile
/datum/component/splattercasting/proc/on_spell_projectile(mob/living/carbon/source, datum/action/cooldown/spell/spell, atom/cast_on, obj/projectile/to_fire)
SIGNAL_HANDLER
if(spell.school == SCHOOL_SANGUINE)
//already has blood themed projectiles
return
playsound(source, 'sound/effects/wounds/splatter.ogg', 60, TRUE, -1)
to_fire.color = "#ff7070"
to_fire.name = "blood-[to_fire.name]"
to_fire.set_light(2, 2, LIGHT_COLOR_BLOOD_MAGIC, l_on = TRUE)
///signal sent before parent casts a spell
/datum/component/splattercasting/proc/on_before_spell_cast(mob/living/carbon/source, datum/action/cooldown/spell/spell, atom/cast_on)
SIGNAL_HANDLER
var/changed_spell = FALSE
if(!(spell.spell_requirements & SPELL_REQUIRES_NO_ANTIMAGIC))
spell.spell_requirements |= SPELL_REQUIRES_NO_ANTIMAGIC
changed_spell = TRUE
if(!(spell.antimagic_flags & MAGIC_RESISTANCE_HOLY))
spell.antimagic_flags |= MAGIC_RESISTANCE_HOLY
changed_spell = TRUE
if(changed_spell)
//we changed some kind of antimagic so we should check if the new version of the spell is still valid.
//since can_cast_spell has already been checked before "before spell cast" only antimagic check should fail
if(!spell.can_cast_spell(feedback = TRUE))
return SPELL_CANCEL_CAST
///signal sent after parent casts a spell
/datum/component/splattercasting/proc/on_after_spell_cast(mob/living/carbon/source, datum/action/cooldown/spell/spell, atom/cast_on)
SIGNAL_HANDLER
if(spell.school == SCHOOL_SANGUINE)
//allows for sanguine spells that work specially with blood to not interact with splattercasting.
//might sound weird, but maybe in the future we'll have a spell that adds blood to the user when it hits a target
//we wouldn't want that to cost blood.
return
//normal cooldown spell has
var/cooldown_remaining = max(spell.next_use_time - world.time,0)
//how much we discount, we make the spell cost 1/10th of its actual cooldown
var/new_cooldown = cooldown_remaining / 10
//convert how much cooldown that spell saved into blood cost
var/blood_cost = (cooldown_remaining - new_cooldown ) * COOLDOWN_TO_BLOOD_RATIO
spell.StartCooldown(new_cooldown)
source.adjust_blood_volume(-blood_cost)
var/cost_desc
switch(blood_cost)
if(1 to 50)
cost_desc = "trickle"
if(51 to 100)
cost_desc = "stream"
if(101 to 200)
cost_desc = "river"
if(201 to INFINITY)
cost_desc = "torrent"
to_chat(source, span_danger("You feel a [cost_desc] of your blood drained into the spell you just cast."))
#undef COOLDOWN_TO_BLOOD_RATIO