Convert max_stamina_modifier to cardio_multiplier

New cardio_multiplier field is applied as a scaling factor to total
cardio fitness, similar to the max_stamina_modifier field it replaces.

Total balance in terms of running distance is now about the same as it
was before cardio.

- Implement cardio_multiplier in get_cardiofit
- Refactor and document update_stamina
- Convert CARDIO mutations to cardio_multiplier
- CRIT mod: Convert Persistent Body to cardio_multiplier
- Update mutation descriptions to reflect cardio effects.
- Replace Debug Stamina mutation with Debug Cardio mutation
- Document stamina_regen_modifier and cardio_multiplier in JSON_INFO
- Remove max_stamina_modifier entirely

data/json/mutations/mutations.json

@@ -232,26 +232,26 @@
     "id": "GOODCARDIO",
     "name": { "str": "Indefatigable" },
     "points": 2,
-    "description": "Whether due to exercise and good diet, or due to a natural propensity to physical endurance, you tire due to physical exertion much less readily than others.  Your maximum stamina is higher than usual.",
+    "description": "Whether due to exercise and good diet, or due to a natural propensity to physical endurance, you tire due to physical exertion much less readily than others.  Your cardio fitness and maximum stamina are higher than usual.",
     "starting_trait": true,
     "valid": false,
     "cancels": [ "BADCARDIO" ],
     "changes_to": [ "GOODCARDIO2" ],
     "category": [ "FISH", "LUPINE", "MOUSE", "INSECT" ],
-    "max_stamina_modifier": 1.25
+    "cardio_multiplier": 1.3
   },
   {
     "type": "mutation",
     "id": "GOODCARDIO2",
     "name": { "str": "Hyperactive" },
     "points": 4,
-    "description": "Your body's efficiency is like that of a tiny furnace, greatly increasing your maximum stamina",
+    "description": "Your body's efficiency is like that of a tiny furnace, greatly increasing your cardio and stamina.",
     "valid": false,
     "prereqs": [ "GOODCARDIO" ],
     "cancels": [ "BADCARDIO" ],
     "threshreq": [ "THRESH_MOUSE", "THRESH_RABBIT" ],
     "category": [ "MOUSE", "RABBIT" ],
-    "max_stamina_modifier": 1.4
+    "cardio_multiplier": 1.6
   },
   {
     "type": "mutation",
@@ -1024,11 +1024,11 @@
     "id": "BADCARDIO",
     "name": { "str": "Languorous" },
     "points": -2,
-    "description": "Whether due to lack of exercise and poor diet, or due to a natural disinclination to physical endurance, you tire due to physical exertion much more readily than others.  Your maximum stamina is lower than usual.",
+    "description": "Whether due to lack of exercise and poor diet, or due to a natural disinclination to physical endurance, you tire due to physical exertion much more readily than others.  Your total cardio fitness and stamina are lower than normal.",
     "starting_trait": true,
     "valid": false,
     "cancels": [ "GOODCARDIO" ],
-    "max_stamina_modifier": 0.75
+    "cardio_multiplier": 0.7
   },
   {
     "type": "mutation",
@@ -7467,12 +7467,12 @@
   },
   {
     "type": "mutation",
-    "id": "DEBUG_STAMINA",
-    "name": { "str": "Debug Stamina" },
+    "id": "DEBUG_CARDIO",
+    "name": { "str": "Debug Cardio" },
     "points": 99,
     "valid": false,
-    "max_stamina_modifier": 999999,
-    "description": "You can't run from the bugs, but you have enough stamina to at least try to.",
+    "cardio_multiplier": 999999,
+    "description": "You can run, but you'll never run out of breath.",
     "debug": true
   },
   {

data/mods/CRT_EXPANSION/mutations/crt_wendigo_mutations.json

@@ -111,7 +111,7 @@
     "threshreq": [ "THRESH_SYLVAN" ],
     "category": [ "SYLVAN" ],
     "cancels": [ "BADCARDIO" ],
-    "max_stamina_modifier": 1.5,
+    "cardio_multiplier": 1.8,
     "stamina_regen_modifier": 0.25
   }
 ]

doc/JSON_INFO.md

@@ -2173,6 +2173,8 @@ The `id` must be exact as it is hardcoded to look for that.
 "metabolism_modifier": 0.333, // Extra metabolism rate multiplier. 1.0 doubles usage, -0.5 halves.
 "fatigue_modifier": 0.5, // Extra fatigue rate multiplier. 1.0 doubles usage, -0.5 halves.
 "fatigue_regen_modifier": 0.333, // Modifier for the rate at which fatigue and sleep deprivation drops when resting.
+"stamina_regen_modifier": 0.1, // Increase stamina regen by this proportion (1.0 being 100% of normal regen)
+"cardio_multiplier": 1.5, // Multiply total cardio fitness by this amount
 "healing_awake": 1.0, // Healing rate per turn while awake.
 "healing_resting": 0.5, // Healing rate per turn while resting.
 "mending_modifier": 1.2 // Multiplier on how fast your limbs mend - This value would make your limbs mend 20% faster

src/character.cpp

@@ -5704,7 +5704,7 @@ mutation_value_map = {
     { "movecost_flatground_modifier", calc_mutation_value_multiplicative<&mutation_branch::movecost_flatground_modifier> },
     { "movecost_obstacle_modifier", calc_mutation_value_multiplicative<&mutation_branch::movecost_obstacle_modifier> },
     { "attackcost_modifier", calc_mutation_value_multiplicative<&mutation_branch::attackcost_modifier> },
-    { "max_stamina_modifier", calc_mutation_value_multiplicative<&mutation_branch::max_stamina_modifier> },
+    { "cardio_multiplier", calc_mutation_value_multiplicative<&mutation_branch::cardio_multiplier> },
     { "weight_capacity_modifier", calc_mutation_value_multiplicative<&mutation_branch::weight_capacity_modifier> },
     { "hearing_modifier", calc_mutation_value_multiplicative<&mutation_branch::hearing_modifier> },
     { "movecost_swim_modifier", calc_mutation_value_multiplicative<&mutation_branch::movecost_swim_modifier> },
@@ -6192,12 +6192,13 @@ int Character::get_stamina_max() const
     // Default base maximum stamina and cardio scaling are defined in data/core/game_balance.json
     static const std::string player_max_stamina( "PLAYER_MAX_STAMINA_BASE" );
     static const std::string player_cardiofit_stamina_scale( "PLAYER_CARDIOFIT_STAMINA_SCALING" );
-    static const std::string max_stamina_modifier( "max_stamina_modifier" );
+
     // Cardiofit stamina mod defaults to 3, and get_cardiofit() should return a value in the vicinity
     // of 1000-4000, so this should add somewhere between 3000 to 12000 stamina.
     int max_stamina = get_option<int>( player_max_stamina ) +
                       get_option<int>( player_cardiofit_stamina_scale ) * get_cardiofit();
     max_stamina = enchantment_cache->modify_value( enchant_vals::mod::MAX_STAMINA, max_stamina );
+
     return max_stamina;
 }
 
@@ -6261,18 +6262,23 @@ void Character::burn_move_stamina( int moves )
 void Character::update_stamina( int turns )
 {
     static const std::string player_base_stamina_regen_rate( "PLAYER_BASE_STAMINA_REGEN_RATE" );
-    static const std::string stamina_regen_modifier( "stamina_regen_modifier" );
     const float base_regen_rate = get_option<float>( player_base_stamina_regen_rate );
-    // Your stamina regen rate works as a function of how fit you are compared to your body size.  This allows it to scale more quickly
-    // than your stamina, so that at higher fitness levels you recover stamina faster.
+    // Your stamina regen rate works as a function of how fit you are compared to your body size.
+    // This allows it to scale more quickly than your stamina, so that at higher fitness levels you
+    // recover stamina faster.
     const float effective_regen_rate = base_regen_rate * get_cardiofit() / base_bmr();
     const int current_stim = get_stim();
-    float stamina_recovery = 0.0f;
-    // Recover some stamina every turn.
+    // Mutations can affect stamina regen via stamina_regen_modifier (0.0 is normal)
+    // Values above or below normal will increase or decrease stamina regen
+    const float mod_regen = mutation_value( "stamina_regen_modifier" );
     // Mutated stamina works even when winded
-    // max stamina modifers from mutation also affect stamina multi
-    float stamina_multiplier = std::max<float>( 0.1f, ( !has_effect( effect_winded ) ? 1.0f : 0.1f ) +
-                               mutation_value( stamina_regen_modifier ) + ( mutation_value( "max_stamina_modifier" ) - 1.0f ) );
+    const float base_multiplier = mod_regen + ( has_effect( effect_winded ) ? 0.1f : 1.0f );
+    // Ensure multiplier is at least 0.1
+    const float stamina_multiplier = std::max<float>( 0.1f, base_multiplier );
+
+    // Recover some stamina every turn. Start with zero, then increase recovery factor based on
+    // mutations, stimulants, and bionics before rolling random recovery based on this factor.
+    float stamina_recovery = 0.0f;
     // But mouth encumbrance interferes, even with mutated stamina.
     stamina_recovery += stamina_multiplier * std::max( 1.0f,
                         effective_regen_rate * get_modifier( character_modifier_stamina_recovery_breathing_mod ) );
@@ -6308,9 +6314,11 @@ void Character::update_stamina( int turns )
         }
     }
 
-    mod_stamina( roll_remainder( stamina_recovery * turns ) );
-    add_msg_debug( debugmode::DF_CHARACTER, "Stamina recovery: %d",
-                   roll_remainder( stamina_recovery * turns ) );
+    // Roll to determine actual stamina recovery over this period
+    int recover_amount = roll_remainder( stamina_recovery * turns );
+    mod_stamina( recover_amount );
+    add_msg_debug( debugmode::DF_CHARACTER, "Stamina recovery: %d", recover_amount );
+
     // Cap at max
     set_stamina( std::min( std::max( get_stamina(), 0 ), max_stam ) );
 }
@@ -6324,19 +6332,30 @@ int Character::get_cardiofit() const
     const int bmr = base_bmr();
     const int athletics_mod = get_skill_level( skill_swimming ) * 10;
     const int health_effect = get_healthy();
-    // Traits now exclusively affect cardio, NOT max_stamina directly. In the future, make cardio_acc also be affected by cardio traits so that they don't become less impactful.
-    const int trait_mod = mutation_value( "max_stamina_modifier" );
+
+    // FIXME: Delete this untruth
+    // Traits now exclusively affect cardio, NOT max_stamina directly. In the future, make
+    // cardio_acc also be affected by cardio traits so that they don't become less impactful.
+    //const int trait_mod = 0;
+
     // At some point we might have proficiencies that affect this.
     const int prof_mod = 0;
     const int cardio_acc_mod = get_cardio_acc();
-    int final_cardio_fitness = bmr / 2 + athletics_mod + health_effect + trait_mod + prof_mod +
-                               cardio_acc_mod;
-    if( final_cardio_fitness > 3 * ( bmr + trait_mod ) ) {
-        // Set a large sane upper limit to cardio fitness. This could be done asymptotically instead of as a sharp cutoff, but the gradual
-        // growth rate of cardio_acc_mod should accomplish that naturally. The BMR will mostly determine this as it is based on the
-        // size of the character, but mutations might push it up.
-        final_cardio_fitness = 3 * ( bmr + trait_mod );
-    }
+
+    // Base formula for cardio fitness
+    int base_cardio_fitness = bmr / 2 + athletics_mod + health_effect + prof_mod + cardio_acc_mod;
+
+    // Apply trait modifier as a scaling factor to total cardio
+    // FIXME: Do this additively as a trait_mod using the original formula, somehow
+    const float scale = mutation_value( "cardio_multiplier" );
+    const float scaled_fitness = base_cardio_fitness * scale;
+
+    // Set a large sane upper limit to cardio fitness. This could be done asymptotically instead of
+    // as a sharp cutoff, but the gradual growth rate of cardio_acc_mod should accomplish that
+    // naturally. The BMR will mostly determine this as it is based on the size of the character,
+    // but mutations might push it up.
+    int final_cardio_fitness = static_cast<int>( std::min( scaled_fitness, 3 * bmr * scale ) );
+
     return final_cardio_fitness;
 }
 

src/mutation.h

@@ -174,7 +174,7 @@ struct mutation_branch {
         cata::optional<float> movecost_flatground_modifier = cata::nullopt;
         cata::optional<float> movecost_obstacle_modifier = cata::nullopt;
         cata::optional<float> attackcost_modifier = cata::nullopt;
-        cata::optional<float> max_stamina_modifier = cata::nullopt;
+        cata::optional<float> cardio_multiplier = cata::nullopt;
         cata::optional<float> weight_capacity_modifier = cata::nullopt;
         cata::optional<float> hearing_modifier = cata::nullopt;
         cata::optional<float> movecost_swim_modifier = cata::nullopt;

src/mutation_data.cpp

@@ -405,7 +405,7 @@ void mutation_branch::load( const JsonObject &jo, const std::string & )
     optional( jo, was_loaded, "movecost_obstacle_modifier", movecost_obstacle_modifier, cata::nullopt );
     optional( jo, was_loaded, "movecost_swim_modifier", movecost_swim_modifier, cata::nullopt );
     optional( jo, was_loaded, "attackcost_modifier", attackcost_modifier, cata::nullopt );
-    optional( jo, was_loaded, "max_stamina_modifier", max_stamina_modifier, cata::nullopt );
+    optional( jo, was_loaded, "cardio_multiplier", cardio_multiplier, cata::nullopt );
     optional( jo, was_loaded, "weight_capacity_modifier", weight_capacity_modifier, cata::nullopt );
     optional( jo, was_loaded, "hearing_modifier", hearing_modifier, cata::nullopt );
     optional( jo, was_loaded, "noise_modifier", noise_modifier, cata::nullopt );