From e21f6c0f926c15537a55e3dd4f9efb5c191d3551 Mon Sep 17 00:00:00 2001
From: Cubitect <cubitect@gmail.com>
Date: Sat, 27 Nov 2021 14:04:05 +0100
Subject: [PATCH] Added variant option to isViableStructurePos.

---
 README.md | 12 +++++-------
 finders.c | 10 +++++++---
 finders.h | 12 +++++++-----
 3 files changed, 19 insertions(+), 15 deletions(-)

diff --git a/README.md b/README.md
index 43835c3..1943e62 100644
--- a/README.md
+++ b/README.md
@@ -173,7 +173,7 @@ int main()
         {
             uint64_t seed = lower48 | (upper16 << 48);
             applySeed(&g, 0, seed);
-            if (isViableStructurePos(structType, &g, p.x, p.z))
+            if (isViableStructurePos(structType, &g, p.x, p.z, 0))
             {
                 printf("Seed %" PRId64 " has a Pillager Outpost at (%d, %d).\n",
                     (int64_t) seed, p.x, p.z);
@@ -250,10 +250,10 @@ int main()
             uint64_t seed = s48 | (high << 48);
             applySeed(&g, 0, seed);
 
-            if (isViableStructurePos(styp, &g, pos[0].x, pos[0].z) &&
-                isViableStructurePos(styp, &g, pos[1].x, pos[1].z) &&
-                isViableStructurePos(styp, &g, pos[2].x, pos[2].z) &&
-                isViableStructurePos(styp, &g, pos[3].x, pos[3].z))
+            if (isViableStructurePos(styp, &g, pos[0].x, pos[0].z, 0) &&
+                isViableStructurePos(styp, &g, pos[1].x, pos[1].z, 0) &&
+                isViableStructurePos(styp, &g, pos[2].x, pos[2].z, 0) &&
+                isViableStructurePos(styp, &g, pos[3].x, pos[3].z, 0))
             {
                 printf("%" PRId64 "\n", (int64_t) seed);
             }
@@ -288,8 +288,6 @@ int main()
     printf("Seed: %" PRId64 "\n", (int64_t) seed);
     printf("Estimated position of first stronghold: (%d, %d)\n", pos.x, pos.z);
 
-    // The finders for the strongholds and spawn require that the seed is
-    // applied to the generator beforehand.
     Generator g;
     setupGenerator(&g, mc, 0);
     applySeed(&g, 0, seed);
diff --git a/finders.c b/finders.c
index 8c907b6..1406f6c 100644
--- a/finders.c
+++ b/finders.c
@@ -1771,7 +1771,7 @@ static int mapViableShore(const Layer * l, int * out, int x, int z, int w, int h
 }
 
 
-int isViableStructurePos(int structureType, Generator *g, int x, int z)
+int isViableStructurePos(int structureType, Generator *g, int x, int z, uint32_t flags)
 {
     int approx = 0; // enables approximation levels
     int viable = 0;
@@ -1878,6 +1878,8 @@ L_feature:
             id = getBiomeAt(g, 0, sampleX, 15, sampleZ);
             if (id < 0 || !isViableFeatureBiome(g->mc, structureType, id))
                 goto L_not_viable;
+            if (flags && (uint32_t) id != flags)
+                goto L_not_viable;
             viable = id; // biome for viablility, useful for further analysis
             goto L_viable;
         }
@@ -1886,6 +1888,8 @@ L_feature:
             const int vv[] = { plains, desert, savanna, taiga, snowy_tundra };
             size_t i;
             for (i = 0; i < sizeof(vv)/sizeof(int); i++) {
+                if (flags && flags != (uint32_t) vv[i])
+                    continue;
                 VillageType vt = getVillageType(g->mc, g->seed, x, z, vv[i]);
                 switch (vt.rotation) {
                     case 0: sampleX = -1+vt.sx; sampleZ = -1+vt.sz; break;
@@ -1897,7 +1901,7 @@ L_feature:
                 sampleX = ((chunkX << 5) + sampleX) / 2 >> 2;
                 sampleZ = ((chunkZ << 5) + sampleZ) / 2 >> 2;
                 id = getBiomeAt(g, 0, sampleX, 15, sampleZ);
-                if (id == vv[i]) {
+                if (id == vv[i] || (id == meadow && vv[i] == plains)) {
                     viable = id;
                     goto L_viable;
                 }
@@ -1946,7 +1950,7 @@ L_feature:
                 {
                     if (g->mc >= MC_1_16)
                         goto L_not_viable;
-                    if (isViableStructurePos(Village, g, p.x, p.z))
+                    if (isViableStructurePos(Village, g, p.x, p.z, 0))
                         goto L_not_viable;
                     goto L_viable;
                 }
diff --git a/finders.h b/finders.h
index a3a93e7..2ee66f7 100644
--- a/finders.h
+++ b/finders.h
@@ -564,14 +564,16 @@ Pos estimateSpawn(const Generator *g);
 // Validating Structure Positions
 //==============================================================================
 
-/* Performs a biome check at the specified block coordinates to determine
+/* Performs a biome check near the specified block coordinates to determine
  * whether a structure of the given type could spawn there. You can get the
  * block positions using getStructurePos().
- * The generator, 'g', should be initialized for a scale 1:1 generation of the
- * correct MC version, dimension and seed. The generator may be temporarily
- * modified during the function call, but will be restored upon return.
+ * The generator, 'g', should be initialized for the correct MC version,
+ * dimension and seed. The generator may be temporarily modified during the
+ * function call, but will be restored upon return.
+ * The 'flags' argument is optional structure specific information, such as the
+ * biome variant for villages.
  */
-int isViableStructurePos(int structType, Generator *g, int blockX, int blockZ);
+int isViableStructurePos(int structType, Generator *g, int blockX, int blockZ, uint32_t flags);
 
 /* Checks if the specified structure type could generate in the given biome.
  */