Weight jokers by rarity in the shop (#152)

* Added weight for the rarity of jokers in the shop

* Includes manual conflict resolution

---------

Co-authored-by: JustinL-12 <jlong30@uic.edu>
Co-authored-by: MeirGavish <meir.gavish@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

include/joker.h

@@ -35,6 +35,14 @@
 #define RARE_JOKER 2
 #define LEGENDARY_JOKER 3
 
+// Percent chance to get a joker of each rarity
+// Note that this deviates slightly from the Balatro wiki to allow legendary
+// jokers to appear without spectral cards implemented
+#define COMMON_JOKER_CHANCE 70
+#define UNCOMMON_JOKER_CHANCE 25
+#define RARE_JOKER_CHANCE 5
+#define LEGENDARY_JOKER_CHANCE 0
+
 #define MAX_JOKER_OBJECTS 32 // The maximum number of joker objects that can be created at once
 
 #define DEFAULT_JOKER_ID 0
@@ -96,5 +104,6 @@ void joker_object_set_selected(JokerObject* joker_object, bool selected);
 bool joker_object_is_selected(JokerObject* joker_object);
 
 Sprite* joker_object_get_sprite(JokerObject* joker_object);
+int joker_get_random_rarity();
 
 #endif // JOKER_H

source/game.c

@@ -2476,6 +2476,42 @@ void erase_price_under_sprite_object(SpriteObject *sprite_object)
     tte_erase_rect_wrapper(price_rect);
 }
 
+static int game_shop_get_random_joker_idx()
+{
+    // Roll for what rarity the joker will be
+    int joker_rarity = joker_get_random_rarity();
+        
+    // Now determine how many jokers are available based on the rarity
+    int jokers_avail_size = list_get_size(jokers_available_to_shop);
+    int matching_indices[jokers_avail_size];
+    int match_count = 0;
+
+    for (int i = 0; i < jokers_avail_size; i++)
+    {
+        intptr_t joker_id = int_list_get(jokers_available_to_shop, i);
+        const JokerInfo *info = get_joker_registry_entry(joker_id); 
+        if (info->rarity == joker_rarity)
+        {
+            matching_indices[match_count] = i;
+            match_count++;
+        }
+    }
+
+    int selected_joker_idx = 0;
+    if (match_count > 0)
+    {
+        // If we counted at least one joker with matching rarity, pick one of them randomly
+        selected_joker_idx = matching_indices[random() % match_count];
+    }
+    else
+    {
+        // Didn't find any jokers of matching rarity, just pick one at random instead
+        selected_joker_idx = random() % jokers_avail_size;
+    }
+
+    return selected_joker_idx;
+}
+
 static void game_shop_create_items()
 {
     tte_erase_rect_wrapper(SHOP_PRICES_TEXT_RECT);
@@ -2489,7 +2525,6 @@ static void game_shop_create_items()
 
     for (int i = 0; i < MAX_SHOP_JOKERS; i++)
     {
-        int joker_idx = 0;
         intptr_t joker_id = 0;
         #ifdef TEST_JOKER_ID0 // Allow defining an ID for a joker to always appear in shop and be tested
         if (int_list_exists(jokers_available_to_shop, TEST_JOKER_ID0))
@@ -2508,9 +2543,8 @@ static void game_shop_create_items()
         else
         #endif
         {
-           joker_idx = random() % list_get_size(jokers_available_to_shop);
+            int joker_idx = game_shop_get_random_joker_idx();
-           joker_id = int_list_get(jokers_available_to_shop, joker_idx);
+            joker_id = int_list_get(jokers_available_to_shop, joker_idx);
-           // TODO: weight the random choice by joker rarity
             list_remove_by_idx(jokers_available_to_shop, joker_idx);
         }
         

source/joker.c

@@ -332,3 +332,27 @@ Sprite* joker_object_get_sprite(JokerObject* joker_object)
         return NULL;
     return sprite_object_get_sprite(joker_object->sprite_object);
 }
+
+int joker_get_random_rarity()
+{
+    int joker_rarity = 0;
+    int rarity_roll = random() % 100; 
+    if (rarity_roll < COMMON_JOKER_CHANCE)  
+    {
+        joker_rarity = COMMON_JOKER;
+    }
+    else if (rarity_roll < COMMON_JOKER_CHANCE + UNCOMMON_JOKER_CHANCE) 
+    {
+        joker_rarity = UNCOMMON_JOKER;
+    }
+    else if (rarity_roll < COMMON_JOKER_CHANCE + UNCOMMON_JOKER_CHANCE + RARE_JOKER_CHANCE)
+    {
+        joker_rarity = RARE_JOKER;
+    }
+    else if (rarity_roll < COMMON_JOKER_CHANCE + UNCOMMON_JOKER_CHANCE + RARE_JOKER_CHANCE + LEGENDARY_JOKER_CHANCE)
+    {
+        joker_rarity = LEGENDARY_JOKER;
+    }
+
+    return joker_rarity;
+}