Allow more customizable XP costs for spell leveling

data/mods/Magiclysm/eoc_spell_learn_boost.json

@@ -1,11 +1,4 @@
 [
-  {
-    "type": "jmath_function",
-    "id": "mc_spell_exp_diff",
-    "num_args": 1,
-    "//": "accept the spell level, return a difference in experience between spell's current level and the next level",
-    "return": "spell_exp_for_level(_0 + 1) - spell_exp_for_level(_0)"
-  },
   {
     "type": "jmath_function",
     "id": "mc_spell_train_focus_factor",
@@ -48,7 +41,7 @@
         "math": [
           "u_spell_exp(_spell)",
           "+=",
-          "mc_spell_exp_diff(u_spell_level(_spell)) / mc_spell_cost_train_factor(_cost, 16, 65) * mc_spell_train_focus_factor(u_val('focus'),u_spell_level(_spell))"
+          "(spell_exp_for_level(_spell, u_spell_level(_spell)+1) - spell_exp_for_level(_spell, u_spell_level(_spell))) / mc_spell_cost_train_factor(_cost, 16, 65) * mc_spell_train_focus_factor(u_val('focus'),u_spell_level(_spell))"
         ]
       }
     ]
@@ -107,7 +100,7 @@
         "math": [
           "u_spell_exp(_spell)",
           "+=",
-          "mc_spell_exp_diff(u_spell_level(_spell)) / mc_spell_cost_train_factor(_cost, 20, 75) * mc_spell_train_focus_factor(u_val('focus'),u_spell_level(_spell))"
+          "(spell_exp_for_level(_spell, u_spell_level(_spell)+1) - spell_exp_for_level(_spell, u_spell_level(_spell))) / mc_spell_cost_train_factor(_cost, 20, 75) * mc_spell_train_focus_factor(u_val('focus'),u_spell_level(_spell))"
         ]
       }
     ]
@@ -124,7 +117,7 @@
         "math": [
           "u_spell_exp(_spell)",
           "+=",
-          "mc_spell_exp_diff(u_spell_level(_spell)) * (_cost / 5000) * mc_spell_train_focus_factor(u_val('focus'),u_spell_level(_spell))"
+          "(spell_exp_for_level(_spell, u_spell_level(_spell)+1) - spell_exp_for_level(_spell, u_spell_level(_spell))) * (_cost / 5000) * mc_spell_train_focus_factor(u_val('focus'),u_spell_level(_spell))"
         ]
       }
     ]
@@ -165,14 +158,14 @@
         "math": [
           "u_spell_exp(_spell)",
           "+=",
-          "mc_spell_exp_diff(u_spell_level(_spell)) / mc_spell_cost_train_factor(_cost, 16, 65) * mc_spell_train_focus_factor(u_val('focus'),u_spell_level(_spell))"
+          "(spell_exp_for_level(_spell, u_spell_level(_spell)+1) - spell_exp_for_level(_spell, u_spell_level(_spell))) / mc_spell_cost_train_factor(_cost, 16, 65) * mc_spell_train_focus_factor(u_val('focus'),u_spell_level(_spell))"
         ]
       },
       {
         "math": [
           "debug_mc_additional_spell_xp",
           "=",
-          "mc_spell_exp_diff(u_spell_level(_spell)) / mc_spell_cost_train_factor(_cost, 16, 65) * mc_spell_train_focus_factor(u_val('focus'),u_spell_level(_spell))"
+          "(spell_exp_for_level(_spell, u_spell_level(_spell)+1) - spell_exp_for_level(_spell, u_spell_level(_spell))) / mc_spell_cost_train_factor(_cost, 16, 65) * mc_spell_train_focus_factor(u_val('focus'),u_spell_level(_spell))"
         ]
       },
       { "u_message": "debug_mc_additional_spell_xp: <global_val:debug_mc_additional_spell_xp>", "type": "debug" }

data/mods/Xedra_Evolved/eocs/chronomancer_eocs.json

@@ -173,7 +173,7 @@
     "effect": [
       {
         "math": [
-          "u_spell_exp('xedra_chronomancer_rewrite_wound_causality') += (spell_exp_for_level(u_spell_level('xedra_chronomancer_rewrite_wound_causality')+1) - spell_exp_for_level(u_spell_level('xedra_chronomancer_rewrite_wound_causality'))) / 20 "
+          "u_spell_exp('xedra_chronomancer_rewrite_wound_causality') += (spell_exp_for_level('xedra_chronomancer_rewrite_wound_causality', u_spell_level('xedra_chronomancer_rewrite_wound_causality')+1) - spell_exp_for_level('xedra_chronomancer_rewrite_wound_causality', u_spell_level('xedra_chronomancer_rewrite_wound_causality'))) / 20 "
         ]
       },
       {
@@ -283,7 +283,7 @@
     "effect": [
       {
         "math": [
-          "u_spell_exp('xedra_chronomancer_rewrite_equipment_causality') += (spell_exp_for_level(u_spell_level('xedra_chronomancer_rewrite_equipment_causality')+1) - spell_exp_for_level(u_spell_level('xedra_chronomancer_rewrite_equipment_causality'))) / 20 "
+          "u_spell_exp('xedra_chronomancer_rewrite_equipment_causality') += (spell_exp_for_level('xedra_chronomancer_rewrite_equipment_causality', u_spell_level('xedra_chronomancer_rewrite_equipment_causality')+1) - spell_exp_for_level('xedra_chronomancer_rewrite_equipment_causality', u_spell_level('xedra_chronomancer_rewrite_equipment_causality'))) / 20 "
         ]
       },
       {

data/mods/Xedra_Evolved/eocs/spell_learning_eoc.json

@@ -11,15 +11,29 @@
       ]
     },
     "effect": [
-      { "math": [ "debug_xe_spell_exp_diff = (spell_exp_diff(u_spell_level(_spell)))" ] },
+      {
+        "math": [
+          "debug_xe_spell_exp_diff = spell_exp_for_level(_spell, u_spell_level(_spell)+1) - spell_exp_for_level(_spell, u_spell_level(_spell))"
+        ]
+      },
       { "math": [ "debug_xe_spell_train_factor = (spell_train_factor(_cost))" ] },
-      { "math": [ "debug_xe_spell_xp_give = spell_exp_diff(u_spell_level(_spell))/spell_train_factor(_cost)" ] },
+      {
+        "math": [
+          "debug_xe_spell_xp_give = (spell_exp_for_level(_spell, u_spell_level(_spell)+1) - spell_exp_for_level(_spell, u_spell_level(_spell)))/spell_train_factor(_cost)"
+        ]
+      },
       { "u_message": "school: <context_val:school>", "type": "debug" },
       { "u_message": "spell: <context_val:spell>", "type": "debug" },
       { "u_message": "spell_exp_diff: <global_val:debug_xe_spell_exp_diff>", "type": "debug" },
       { "u_message": "spell_train_factor: <global_val:debug_xe_spell_train_factor>", "type": "debug" },
       { "u_message": "amount of XP added: <global_val:debug_xe_spell_xp_give>", "type": "debug" },
-      { "math": [ "u_spell_exp(_spell)", "+=", "spell_exp_diff(u_spell_level(_spell))/spell_train_factor(_cost)" ] }
+      {
+        "math": [
+          "u_spell_exp(_spell)",
+          "+=",
+          "(spell_exp_for_level(_spell, u_spell_level(_spell)+1) - spell_exp_for_level(_spell, u_spell_level(_spell)))/spell_train_factor(_cost)"
+        ]
+      }
     ]
   },
   {

data/mods/Xedra_Evolved/jmath.json

@@ -23,13 +23,6 @@
     "num_args": 3,
     "return": " ((_0 * _1) + _2) * scaling_factor(u_val('intelligence'))"
   },
-  {
-    "type": "jmath_function",
-    "id": "spell_exp_diff",
-    "num_args": 1,
-    "//": "accept the spell level, return a difference in experience between spell's current level and the next level",
-    "return": "spell_exp_for_level(_0 + 1) - spell_exp_for_level(_0)"
-  },
   {
     "type": "jmath_function",
     "id": "spell_time",

data/mods/Xedra_Evolved/spells/spell_eocs.json

@@ -99,7 +99,7 @@
         "math": [
           "u_spell_exp('xedra_dreamer_generate_accelerated_time')",
           "+=",
-          "spell_exp_diff(u_spell_level('xedra_dreamer_generate_accelerated_time'))/spell_train_factor(200)"
+          "(spell_exp_for_level('xedra_dreamer_generate_accelerated_time', u_spell_level('xedra_dreamer_generate_accelerated_time')+1) - spell_exp_for_level('xedra_dreamer_generate_accelerated_time', u_spell_level('xedra_dreamer_generate_accelerated_time')))/spell_train_factor(200)"
         ]
       }
     ],
@@ -143,7 +143,7 @@
         "math": [
           "u_spell_exp('spell_ethereal_wings')",
           "+=",
-          "spell_exp_diff(u_spell_level('spell_ethereal_wings'))/spell_train_factor(200)"
+          "(spell_exp_for_level('spell_ethereal_wings', u_spell_level('spell_ethereal_wings')+1) - spell_exp_for_level('spell_ethereal_wings', u_spell_level('spell_ethereal_wings')))/spell_train_factor(200)"
         ]
       }
     ],
@@ -184,7 +184,11 @@
         "time_in_future": { "math": [ "((u_spell_level('spell_karma_arms')+1)*500)" ] }
       },
       {
-        "math": [ "u_spell_exp('spell_karma_arms')", "+=", "spell_exp_diff(u_spell_level('spell_karma_arms'))/spell_train_factor(200)" ]
+        "math": [
+          "u_spell_exp('spell_karma_arms')",
+          "+=",
+          "(spell_exp_for_level('spell_karma_arms', u_spell_level('spell_karma_arms')+1) - spell_exp_for_level('spell_karma_arms', u_spell_level('spell_karma_arms')))/spell_train_factor(200)"
+        ]
       }
     ],
     "false_effect": [
@@ -218,7 +222,11 @@
         "time_in_future": { "math": [ "((u_spell_level('spell_devil_tail')+1)*900)" ] }
       },
       {
-        "math": [ "u_spell_exp('spell_devil_tail')", "+=", "spell_exp_diff(u_spell_level('spell_devil_tail'))/spell_train_factor(100)" ]
+        "math": [
+          "u_spell_exp('spell_devil_tail')",
+          "+=",
+          "(spell_exp_for_level('spell_devil_tail', u_spell_level('spell_devil_tail')+1) - spell_exp_for_level('spell_devil_tail', u_spell_level('spell_devil_tail')))/spell_train_factor(100)"
+        ]
       }
     ],
     "false_effect": [ { "u_lose_trait": "devil_tail" }, { "u_message": "Your devil tail fades away.", "type": "neutral" } ]
@@ -258,7 +266,7 @@
         "math": [
           "u_spell_exp('spell_stalker_eyes')",
           "+=",
-          "spell_exp_diff(u_spell_level('spell_stalker_eyes'))/spell_train_factor(200)"
+          "(spell_exp_for_level('spell_stalker_eyes', u_spell_level('spell_stalker_eyes')+1) - spell_exp_for_level('spell_stalker_eyes', u_spell_level('spell_stalker_eyes')))/spell_train_factor(200)"
         ]
       }
     ],

doc/MAGIC.md

@@ -67,6 +67,8 @@ In `data/mods/Magiclysm` there is a template spell, copied here for your perusal
     "components": [requirement_id]                            // an id from a requirement, like the ones you use for crafting. spell components require to cast.
     "difficulty": 12,                                         // the difficulty to learn/cast the spell
     "max_level": 10,                                          // maximum level you can achieve in the spell
+    "get_level_formula_id": "jmath_get_level_formula",        // The id of a jmath formula that calculates what level the spell is for a given exp value.  Must be the inverse of exp_for_level_formula_id.
+    "exp_for_level_formula_id": "jmath_exp_for_level_formula",// The id of a jmath formula that calculates how much exp is required for a given level.  Must be the inverse of get_level_formula_id.
     "min_accuracy" -20,                                       // the accuracy bonus of the spell. around -15 and it gets blocked all the time
     "max_accuracy": 20,                                       // around 20 accuracy and it's basically impossible to block
     "accuracy_increment": 1.5
@@ -615,6 +617,42 @@ Explanation: Here we have one main spell with two subspells: one on the caster a
 
 See [Monster special attacks - Spells](MONSTER_SPECIAL_ATTACKS.md#spell-monster-spells).
 
+### Custom Spell Experience Requirements
+
+Spells may have custom formulas for their xp requirements to level by combining the `get_level_formula_id` and `exp_for_level_formula_id` fields.
+These fields both take the id of a jmath_function that they can use to calculate the xp requirement instead of the default formula.
+The given jmath functions must only have 1 argument (for the spell level or experience) and they should not make any calls to the alpha or beta talkers.  Spell calculations are intended to be character agnostic, and while using functions such as u_skill('DEDUCTION') will not error, it will always be calculated from the player characters data, even if for an npc or other uses of spell xp calculations.
+Also, keep in mind that changing the spell experience requirements of an existing spell will likely do strange things to any characters that already knew the spell before the xp requirements were changed.
+
+Note: the exp_for_level_formula_id requires the total experience required for a spell level, not the difference in experience between the current and next level.  IE, if a spell requires 1000 xp to level a level 10 spell should require 10,000 experience in its exp_for_level_formula_id, not 1,000.
+
+Constant Spell Exp Requirement Example:
+  {
+    "id": "test_spell",
+    "type": "SPELL",
+    "name": "test",
+    "description": "constant spell experience formula.",
+    "valid_targets": [ "hostile" ],
+    "effect": "attack",
+    "min_damage": 1,
+    "max_damage": 1,
+    "get_level_formula_id": "magic_test_func_get_level",
+    "exp_for_level_formula_id": "magic_test_func_exp_for_level"
+  },
+  {
+    "type": "jmath_function",
+    "id": "magic_test_func_get_level",
+    "num_args": 1,
+    "return": "_0 / 1000"
+  },
+  {
+    "type": "jmath_function",
+    "id": "magic_test_func_exp_for_level",
+    "num_args": 1,
+    "return": "1000 * _0"
+  },
+```
+
 
 ## Enchantments
 

doc/NPCs.md

@@ -1361,7 +1361,7 @@ _some functions support array arguments or kwargs, denoted with square brackets
 | skill(`s`/`v`)    |  ✅  |   ✅   | u, n  | Return or set skill level<br/><br/>Example:<br/>`"condition": { "math": [ "u_skill('driving') >= 5"] }`<br/>`"condition": { "math": [ "u_skill(someskill) >= 5"] }`|
 | skill_exp(`s`/`v`)    |  ✅  |   ✅   | u, n  | Return or set skill experience<br/> Argument is skill ID. <br/><br/> Optional kwargs:<br/>`format`: `s`/`v` - must be `percentage` or `raw`.<br/><br/>Example:<br/>`{ "math": [ "u_skill_exp('driving', 'format': crt_format)--"] }`|
 | spell_exp(`s`/`v`)    |  ✅  |   ✅   | u, n  | Return or set spell xp<br/> Example:<br/>`"condition": { "math": [ "u_spell_exp('SPELL_ID') >= 5"] }`|
-| spell_exp_for_level(`d`/`v`)    |  ✅  |   ❌   | g  | Return the amount of XP necessary for a spell level. <br/> Example:<br/>`"math": [ "spell_exp_for_level(u_spell_level('SPELL_ID')) * 5"] }`|
+| spell_exp_for_level(`s`/`v`, `d`/`v`)    |  ✅  |   ❌   | g  | Return the amount of XP necessary for a spell level for the given spell. Arguments are spell id and desired level.  <br/> Example:<br/>`"math": [ "spell_exp_for_level('SPELL_ID', u_spell_level('SPELL_ID') ) * 5"] }`|
 | spell_count()    |  ✅   |   ❌  | u, n  | Return number of spells the character knows.<br/><br/> Optional kwargs:<br/>`school`: `s/v` - return number of spells known of that school.<br/><br/> Example:<br/>`"condition": { "math": [ "u_spell_count('school': 'MAGUS') >= 10"] }`|
 | spell_level_sum()    |  ✅   |   ❌  | u, n  | Return sum of all spell levels character has; having one spell of class A with level 5, and another with lvl 10 would return 15. <br/><br/> Optional kwargs:<br/>`school`: `s/v` - return number of spells known of that school. Omitting return sum of all spells character has, no matter of the class.<br/>`level`: `d/v` - count only spells that are higher or equal this field. Default 0.<br/><br/> Example:<br/>`{ "math": [ "test_var1 = u_spell_level_sum()" ] }`<br/>`{ "math": [ "test_var2 = u_spell_level_sum('school': 'MAGUS')" ] }`<br/>`{ "math": [ "test_var3 = u_spell_level_sum('school': 'MAGUS', 'level': '10')" ] }`|
 | spell_level(`s`/`v`)    |  ✅   |   ✅  | u, n  | Return or set level of a given spell. -1 means the spell is not known when read and that the spell should be forgotten if written.<br/>Argument is spell ID. If `"null"` is given, return the highest level of spells the character knows (read only).<br/> Example:<br/>`"condition": { "math": [ "u_spell_level('SPELL_ID') == -1"] }`|

src/debug_menu.cpp

@@ -1387,7 +1387,9 @@ static void change_spells( Character &character )
             character.magic->get_spellbook().emplace( splt.id, spl );
         }
 
-        character.magic->get_spell( splt.id ).set_exp( spell::exp_for_level( spell_level ) );
+        // storing the spell to be used instead of getting it twice somehow breaks the debug functionality.
+        int set_to_exp = character.magic->get_spell( splt.id ).exp_for_level( spell_level );
+        character.magic->get_spell( splt.id ).set_exp( set_to_exp );
     };
 
     ui_adaptor spellsui;

src/magic.cpp

@@ -38,6 +38,7 @@
 #include "magic_enchantment.h"
 #include "map.h"
 #include "map_iterator.h"
+#include "math_parser_jmath.h"
 #include "messages.h"
 #include "mongroup.h"
 #include "monster.h"
@@ -486,6 +487,13 @@ void spell_type::load( const JsonObject &jo, const std::string_view src )
     optional( jo, was_loaded, "spell_class", spell_class, spell_class_default );
     optional( jo, was_loaded, "energy_source", energy_source, energy_source_default );
     optional( jo, was_loaded, "damage_type", dmg_type, dmg_type_default );
+    optional( jo, was_loaded, "get_level_formula_id", get_level_formula_id );
+    optional( jo, was_loaded, "exp_for_level_formula_id", exp_for_level_formula_id );
+    if( ( get_level_formula_id.has_value() && !exp_for_level_formula_id.has_value() ) ||
+        ( !get_level_formula_id.has_value() && exp_for_level_formula_id.has_value() ) ) {
+        debugmsg( "spell id:%s has a get_level_formula_id or exp_for_level_formula_id but not the other!  This breaks the calculations for xp/level!",
+                  id.c_str() );
+    }
     if( !was_loaded || jo.has_member( "difficulty" ) ) {
         difficulty = get_dbl_or_var( jo, "difficulty", false, difficulty_default );
     }
@@ -624,6 +632,8 @@ void spell_type::serialize( JsonOut &json ) const
                  static_cast<int>( base_casting_time.min.dbl_val.value() ) );
     json.member( "casting_time_increment",
                  static_cast<float>( casting_time_increment.min.dbl_val.value() ), casting_time_increment_default );
+    json.member( "get_level_formula_id", get_level_formula_id );
+    json.member( "exp_for_level_formula_id", exp_for_level_formula_id );
 
     if( !learn_spells.empty() ) {
         json.member( "learn_spells" );
@@ -675,6 +685,13 @@ void spell_type::check_consistency()
         if( sp_t.spell_tags[spell_flag::WONDER] && sp_t.additional_spells.empty() ) {
             debugmsg( "ERROR: %s has WONDER flag but no spells to choose from!", sp_t.id.c_str() );
         }
+        if( sp_t.exp_for_level_formula_id.has_value() &&
+            sp_t.exp_for_level_formula_id.value()->num_params != 1 ) {
+            debugmsg( "ERROR: %s exp_for_level_formula_id has params that != 1!", sp_t.id.c_str() );
+        }
+        if( sp_t.get_level_formula_id.has_value() && sp_t.get_level_formula_id.value()->num_params != 1 ) {
+            debugmsg( "ERROR: %s get_level_formula_id has params that != 1!", sp_t.id.c_str() );
+        }
     }
 }
 
@@ -1651,9 +1668,6 @@ bool spell::ignore_by_species_id( const tripoint_bub_ms &p ) const
     return valid;
 }
 
-
-
-
 std::string spell::description() const
 {
     return type->description.translated();
@@ -1682,8 +1696,18 @@ static constexpr double b = 0.146661;
 static constexpr double c = -62.5;
 
 int spell::get_level() const
+{
+    return type->get_level( experience );
+}
+
+int spell_type::get_level( int experience ) const
 {
     // you aren't at the next level unless you have the requisite xp, so floor
+    if( get_level_formula_id.has_value() ) {
+        return std::max( static_cast<int>( std::floor( get_level_formula_id.value()->eval( dialogue(
+                                               std::make_unique<talker>(), nullptr ), { static_cast<double>( experience ) } ) ) ), 0 );
+    }
+
     return std::max( static_cast<int>( std::floor( std::log( experience + a ) / b + c ) ), 0 );
 }
 
@@ -1755,12 +1779,21 @@ void spell::clear_temp_adjustments()
 // helper function to calculate xp needed to be at a certain level
 // pulled out as a helper function to make it easier to either be used in the future
 // or easier to tweak the formula
-int spell::exp_for_level( int level )
+int spell::exp_for_level( int level ) const
+{
+    return type->exp_for_level( level );
+}
+
+int spell_type::exp_for_level( int level ) const
 {
     // level 0 never needs xp
     if( level == 0 ) {
         return 0;
     }
+    if( exp_for_level_formula_id.has_value() ) {
+        return std::ceil( exp_for_level_formula_id.value()->eval( dialogue( std::make_unique<talker>(),
+                          nullptr ), { static_cast<double>( level ) } ) );
+    }
     return std::ceil( std::exp( ( level - c ) * b ) ) - a;
 }