Biome generation

2026-03-19 13:45:33 -05:00
parent fedb426cfc
commit 6d97e5324c
8 changed files with 376 additions and 36 deletions
@@ -9,6 +9,89 @@ public class CharacterStore
    private readonly IMongoCollection<Character> _col;
    private readonly IMongoCollection<BsonDocument> _locations;
    private const string CoordIndexName = "coord_x_1_coord_y_1";
+    private const int WorldSeed = 1729;
+    private static readonly string[] BiomeOrder = ["plains", "forest", "wetlands", "rocky", "desert"];
+    private static readonly Dictionary<string, BiomeDefinition> Biomes = new()
+    {
+        ["plains"] = new BiomeDefinition(
+            "plains",
+            3.0,
+            new Dictionary<string, double>
+            {
+                ["forest"] = 1.7,
+                ["wetlands"] = 0.9,
+                ["rocky"] = 0.8,
+                ["desert"] = 0.4
+            },
+            new[]
+            {
+                new ResourceRule("grass", 180, 420, 12),
+                new ResourceRule("wood", 25, 90, 3),
+                new ResourceRule("stone", 10, 40, 2)
+            }),
+        ["forest"] = new BiomeDefinition(
+            "forest",
+            3.4,
+            new Dictionary<string, double>
+            {
+                ["plains"] = 1.6,
+                ["wetlands"] = 1.3,
+                ["rocky"] = 0.5,
+                ["desert"] = 0.1
+            },
+            new[]
+            {
+                new ResourceRule("wood", 220, 520, 6),
+                new ResourceRule("grass", 90, 220, 8),
+                new ResourceRule("stone", 15, 45, 2)
+            }),
+        ["wetlands"] = new BiomeDefinition(
+            "wetlands",
+            3.1,
+            new Dictionary<string, double>
+            {
+                ["forest"] = 1.5,
+                ["plains"] = 1.1,
+                ["rocky"] = 0.2,
+                ["desert"] = 0.05
+            },
+            new[]
+            {
+                new ResourceRule("grass", 260, 600, 15),
+                new ResourceRule("wood", 40, 120, 4)
+            }),
+        ["rocky"] = new BiomeDefinition(
+            "rocky",
+            3.0,
+            new Dictionary<string, double>
+            {
+                ["plains"] = 1.2,
+                ["forest"] = 0.6,
+                ["desert"] = 1.1,
+                ["wetlands"] = 0.1
+            },
+            new[]
+            {
+                new ResourceRule("stone", 220, 540, 8),
+                new ResourceRule("wood", 10, 40, 2),
+                new ResourceRule("grass", 20, 70, 4)
+            }),
+        ["desert"] = new BiomeDefinition(
+            "desert",
+            3.2,
+            new Dictionary<string, double>
+            {
+                ["rocky"] = 1.4,
+                ["plains"] = 0.8,
+                ["forest"] = 0.1,
+                ["wetlands"] = 0.05
+            },
+            new[]
+            {
+                new ResourceRule("stone", 80, 220, 5),
+                new ResourceRule("grass", 5, 25, 2)
+            })
+    };

    public sealed record VisibleLocationResult(List<VisibleLocation> Locations, int GeneratedCount);

@@ -82,31 +165,8 @@ public class CharacterStore
        {
            for (var y = character.Coord.Y - radius; y <= character.Coord.Y + radius; y++)
            {
-                var filter = Builders<BsonDocument>.Filter.And(
-                    Builders<BsonDocument>.Filter.Eq("coord.x", x),
-                    Builders<BsonDocument>.Filter.Eq("coord.y", y)
-                );
-
-                var update = Builders<BsonDocument>.Update
-                    .SetOnInsert("_id", ObjectId.GenerateNewId())
-                    .SetOnInsert("name", DefaultLocationName(x, y))
-                    .SetOnInsert("coord", new BsonDocument
-                    {
-                        { "x", x },
-                        { "y", y }
-                    })
-                    .SetOnInsert("createdUtc", DateTime.UtcNow);
-
-                try
-                {
-                    var result = await _locations.UpdateOneAsync(filter, update, new UpdateOptions { IsUpsert = true });
-                    if (result.UpsertedId is not null)
-                        generatedCount += 1;
-                }
-                catch (MongoWriteException ex) when (ex.WriteError.Category == ServerErrorCategory.DuplicateKey)
-                {
-                    // Another request or service instance created it first.
-                }
+                if (await EnsureLocationStateAsync(x, y))
+                    generatedCount += 1;
            }
        }

@@ -141,10 +201,203 @@ public class CharacterStore
                X = coord.GetValue("x", 0).ToInt32(),
                Y = coord.GetValue("y", 0).ToInt32()
            },
+            BiomeKey = document.GetValue("biomeKey", "plains").AsString,
            Resources = MapVisibleLocationResources(document)
        };
    }

+    private async Task<bool> EnsureLocationStateAsync(int x, int y)
+    {
+        var filter = Builders<BsonDocument>.Filter.And(
+            Builders<BsonDocument>.Filter.Eq("coord.x", x),
+            Builders<BsonDocument>.Filter.Eq("coord.y", y)
+        );
+
+        var existing = await _locations.Find(filter).FirstOrDefaultAsync();
+        if (existing is not null)
+        {
+            await BackfillLocationStateAsync(existing);
+            return false;
+        }
+
+        var biomeKey = await DetermineBiomeKeyAsync(x, y);
+        var update = Builders<BsonDocument>.Update
+            .SetOnInsert("_id", ObjectId.GenerateNewId())
+            .SetOnInsert("name", DefaultLocationName(x, y))
+            .SetOnInsert("coord", new BsonDocument
+            {
+                { "x", x },
+                { "y", y }
+            })
+            .SetOnInsert("biomeKey", biomeKey)
+            .SetOnInsert("resources", BuildResourcesDocument(biomeKey, x, y))
+            .SetOnInsert("createdUtc", DateTime.UtcNow);
+
+        try
+        {
+            var result = await _locations.UpdateOneAsync(filter, update, new UpdateOptions { IsUpsert = true });
+            return result.UpsertedId is not null;
+        }
+        catch (MongoWriteException ex) when (ex.WriteError.Category == ServerErrorCategory.DuplicateKey)
+        {
+            return false;
+        }
+    }
+
+    private async Task BackfillLocationStateAsync(BsonDocument document)
+    {
+        var coord = document.GetValue("coord", new BsonDocument()).AsBsonDocument;
+        var x = coord.GetValue("x", 0).ToInt32();
+        var y = coord.GetValue("y", 0).ToInt32();
+
+        var updates = new List<UpdateDefinition<BsonDocument>>();
+        var biomeKey = document.GetValue("biomeKey", BsonNull.Value).IsBsonNull
+            ? await DetermineBiomeKeyAsync(x, y)
+            : document.GetValue("biomeKey", "plains").AsString;
+
+        if (!document.Contains("biomeKey"))
+            updates.Add(Builders<BsonDocument>.Update.Set("biomeKey", biomeKey));
+        if (!document.Contains("resources"))
+            updates.Add(Builders<BsonDocument>.Update.Set("resources", BuildResourcesDocument(biomeKey, x, y)));
+
+        if (updates.Count == 0)
+            return;
+
+        var id = document.GetValue("_id").AsObjectId;
+        await _locations.UpdateOneAsync(
+            Builders<BsonDocument>.Filter.Eq("_id", id),
+            Builders<BsonDocument>.Update.Combine(updates));
+    }
+
+    private async Task<string> DetermineBiomeKeyAsync(int x, int y)
+    {
+        if (x == 0 && y == 0)
+            return "plains";
+
+        var neighbors = await LoadNeighborBiomeKeysAsync(x, y);
+        var baseBiome = DetermineBaseBiomeKey(x, y);
+        if (neighbors.Count == 0)
+            return baseBiome;
+
+        var dominantNeighbor = neighbors
+            .GroupBy(key => key)
+            .OrderByDescending(group => group.Count())
+            .ThenBy(group => group.Key)
+            .First().Key;
+
+        var bestBiome = baseBiome;
+        var bestScore = double.NegativeInfinity;
+        foreach (var candidate in BiomeOrder)
+        {
+            var score = candidate == baseBiome ? 2.5 : 0.35;
+            if (candidate == dominantNeighbor)
+                score += 1.8;
+
+            foreach (var neighbor in neighbors)
+            {
+                if (!Biomes.TryGetValue(neighbor, out var neighborDefinition))
+                    continue;
+
+                if (candidate == neighbor)
+                    score += neighborDefinition.ContinuationWeight;
+                else if (neighborDefinition.TransitionWeights.TryGetValue(candidate, out var transitionWeight))
+                    score += transitionWeight;
+            }
+
+            score += StableNoise(x, y, StableHash(candidate)) * 0.25;
+            if (score > bestScore)
+            {
+                bestScore = score;
+                bestBiome = candidate;
+            }
+        }
+
+        return bestBiome;
+    }
+
+    private async Task<List<string>> LoadNeighborBiomeKeysAsync(int x, int y)
+    {
+        var coords = new[]
+        {
+            (x - 1, y),
+            (x + 1, y),
+            (x, y - 1),
+            (x, y + 1)
+        };
+
+        var filters = coords.Select(coord =>
+            Builders<BsonDocument>.Filter.And(
+                Builders<BsonDocument>.Filter.Eq("coord.x", coord.Item1),
+                Builders<BsonDocument>.Filter.Eq("coord.y", coord.Item2)))
+            .ToList();
+        var filter = Builders<BsonDocument>.Filter.Or(filters);
+        var neighbors = await _locations.Find(filter).ToListAsync();
+
+        return neighbors
+            .Where(doc => doc.Contains("biomeKey"))
+            .Select(doc => doc.GetValue("biomeKey", "plains").AsString)
+            .Where(key => !string.IsNullOrWhiteSpace(key))
+            .ToList();
+    }
+
+    private static string DetermineBaseBiomeKey(int x, int y)
+    {
+        var temperature = StableNoise(x, y, 101);
+        var moisture = StableNoise(x, y, 202);
+        var ruggedness = StableNoise(x, y, 303);
+
+        if (ruggedness > 0.74)
+            return "rocky";
+        if (moisture > 0.72 && temperature < 0.75)
+            return "wetlands";
+        if (moisture > 0.56)
+            return "forest";
+        if (moisture < 0.22 && temperature > 0.58)
+            return "desert";
+        return "plains";
+    }
+
+    private static BsonArray BuildResourcesDocument(string biomeKey, int x, int y)
+    {
+        if (!Biomes.TryGetValue(biomeKey, out var biome))
+            biome = Biomes["plains"];
+
+        var resources = new BsonArray();
+        foreach (var rule in biome.ResourceRules)
+        {
+            var roll = StableNoise(x, y, StableHash(rule.ItemKey));
+            var quantity = rule.MinQuantity + (int)Math.Round(roll * (rule.MaxQuantity - rule.MinQuantity));
+            if (quantity <= 0)
+                continue;
+
+            resources.Add(new BsonDocument
+            {
+                { "itemKey", rule.ItemKey },
+                { "remainingQuantity", quantity },
+                { "gatherQuantity", rule.GatherQuantity }
+            });
+        }
+
+        return resources;
+    }
+
+    private static double StableNoise(int x, int y, int salt)
+    {
+        var value = Math.Sin((x * 12.9898) + (y * 78.233) + ((WorldSeed + salt) * 0.1597)) * 43758.5453;
+        return value - Math.Floor(value);
+    }
+
+    private static int StableHash(string value)
+    {
+        unchecked
+        {
+            var hash = 23;
+            foreach (var c in value)
+                hash = (hash * 31) + c;
+            return hash;
+        }
+    }
+
    private static List<VisibleLocationResource> MapVisibleLocationResources(BsonDocument document)
    {
        if (!document.TryGetValue("resources", out var resourcesValue) || resourcesValue.BsonType != BsonType.Array)
@@ -216,7 +469,15 @@ public class CharacterStore
            );
        }

-        var result = await _col.DeleteOneAsync(filter);
-        return result.DeletedCount > 0;
-    }
-}
+        var result = await _col.DeleteOneAsync(filter);
+        return result.DeletedCount > 0;
+    }
+
+    private sealed record ResourceRule(string ItemKey, int MinQuantity, int MaxQuantity, int GatherQuantity);
+
+    private sealed record BiomeDefinition(
+        string Key,
+        double ContinuationWeight,
+        Dictionary<string, double> TransitionWeights,
+        IReadOnlyList<ResourceRule> ResourceRules);
+}