From 136e645ce9c54cb24c659b29a24fa6f8361a3fef Mon Sep 17 00:00:00 2001
From: Cubitect <cubitect@gmail.com>
Date: Mon, 11 Apr 2022 11:49:37 +0200
Subject: [PATCH] Added available biome checker

---
 finders.c | 36 ++++++++++++++++++++++++++++++------
 finders.h | 12 ++++++++++--
 2 files changed, 40 insertions(+), 8 deletions(-)

diff --git a/finders.c b/finders.c
index 9fabe13..2f00931 100644
--- a/finders.c
+++ b/finders.c
@@ -2676,8 +2676,7 @@ BiomeFilter setupBiomeFilter(
 }
 
 
-typedef struct
-{
+typedef struct {
     Generator *g;
     int *ids;
     Range r;
@@ -2812,7 +2811,7 @@ int checkForBiomes(
             //if (err) break;
         }
         while (0);
-        if (err || (stop && *stop) || (flags & CFB_APPROX)) 
+        if (err || (stop && *stop) || (flags & CFB_APPROX))
             goto L_end;
     }
 
@@ -2879,12 +2878,12 @@ int checkForBiomes(
         }
         else
         {   // no excluded: do the current biomes satisfy the condition?
-            if (((info.b & info.breq) ^ info.breq) == 0 && 
+            if (((info.b & info.breq) ^ info.breq) == 0 &&
                 ((info.m & info.mreq) ^ info.mreq) == 0)
                 break;
         }
     }
-    
+
 L_end:
     if (stop && *stop)
     {
@@ -2896,7 +2895,7 @@ L_end:
         if (flags & CFB_MATCH_ANY)
             ret &= (info.b & info.breq) || (info.m & info.mreq);
         else
-            ret &= (((info.b & info.breq) ^ info.breq) == 0 && 
+            ret &= (((info.b & info.breq) ^ info.breq) == 0 &&
                     ((info.m & info.mreq) ^ info.mreq) == 0);
     }
 
@@ -3510,6 +3509,31 @@ int canBiomeGenerate(int layerId, int mc, int id)
     return isOverworld(mc, id);
 }
 
+void getAvailableBiomes(uint64_t *mL, uint64_t *mM, int layerId, int mc)
+{
+    *mL = *mM = 0;
+    int i;
+    if (mc >= MC_1_18)
+    {
+        for (i = 0; i < 64; i++)
+        {
+            if (isOverworld(mc, i))
+                *mL |= (1ULL << i);
+            if (isOverworld(mc, i+128))
+                *mM |= (1ULL << i);
+        }
+    }
+    else
+    {
+        for (i = 0; i < 64; i++)
+        {
+            if (canBiomeGenerate(layerId, mc, i))
+                *mL |= (1ULL << i);
+            if (canBiomeGenerate(layerId, mc, i+128))
+                *mM |= (1ULL << i);
+        }
+    }
+}
 
 // TODO: This function requires testing across versions
 void genPotential(uint64_t *mL, uint64_t *mM, int layer, int mc, int id)
diff --git a/finders.h b/finders.h
index 55a0cea..5dbb95f 100644
--- a/finders.h
+++ b/finders.h
@@ -134,6 +134,7 @@ STRUCT(BiomeFilter)
     uint64_t oceanToFind; // all required ocean types
 
     int specialCnt; // number of special temperature categories required
+    int padding[1]; // unused
 
     // excluded biomes that shall not be present
     uint64_t biomeToExcl, biomeToExclM;
@@ -726,13 +727,20 @@ int checkForTemps(LayerStack *g, uint64_t seed, int x, int z, int w, int h, cons
  */
 int canBiomeGenerate(int layerId, int mc, int biomeID);
 
-/* Given a biome 'id' at a generation 'layer', this functions finds which
+/* Given a biome 'id' at a generation 'layerId', this functions finds which
  * biomes may generate from it. The result is stored in the bitfields:
  * mL : for ids 0-63
  * mM : for ids 128-191
  */
-void genPotential(uint64_t *mL, uint64_t *mM, int layer, int mc, int id);
+void genPotential(uint64_t *mL, uint64_t *mM, int layerId, int mc, int id);
 
+/* Gets the biomes that can generate in the given version and layer ID.
+ * In contrast to canBiomeGenerate() and genPotential() it also supports 1.18+,
+ * where the layerId is ignored.
+ * mL : for ids 0-63
+ * mM : for ids 128-191
+ */
+void getAvailableBiomes(uint64_t *mL, uint64_t *mM, int layerId, int mc);
 
 //==============================================================================
 // Biome Noise Finders (for 1.18+)