Add subtle island terrain relief

worldgen-c/include/worldgen.h

@@ -61,7 +61,17 @@
 		BLOCK_STONE_BRICK_STAIRS_E = 48,
 		BLOCK_STONE_BRICK_STAIRS_W = 49,
 		BLOCK_STONE_BRICK_STAIRS_N = 50,
-		BLOCK_STONE_BRICK_STAIRS_S = 51
+		BLOCK_STONE_BRICK_STAIRS_S = 51,
+		BLOCK_DANDELION = 52,
+		BLOCK_AZURE_BLUET = 53,
+		BLOCK_OXEYE_DAISY = 54,
+		BLOCK_CORNFLOWER = 55,
+		BLOCK_LILY_OF_THE_VALLEY = 56,
+		BLOCK_FERN = 57,
+		BLOCK_CLAY = 58,
+		BLOCK_SEAGRASS = 59,
+		BLOCK_IRON_BARS_NS = 60,
+		BLOCK_IRON_BARS_EW = 61
 	};
 
 struct trail_segment;

worldgen-c/src/main.c

@@ -100,6 +100,8 @@ static const kv_pair PROPS_LADDER_N[] = {{"facing", "north"}, {"waterlogged", "f
 static const kv_pair PROPS_LADDER_S[] = {{"facing", "south"}, {"waterlogged", "false"}};
 static const kv_pair PROPS_LADDER_W[] = {{"facing", "west"}, {"waterlogged", "false"}};
 static const kv_pair PROPS_LADDER_E[] = {{"facing", "east"}, {"waterlogged", "false"}};
+static const kv_pair PROPS_IRON_BARS_NS[] = {{"east", "false"}, {"north", "true"}, {"south", "true"}, {"waterlogged", "false"}, {"west", "false"}};
+static const kv_pair PROPS_IRON_BARS_EW[] = {{"east", "true"}, {"north", "false"}, {"south", "false"}, {"waterlogged", "false"}, {"west", "true"}};
 static const size_t BLOCK_STATE_CAP = 256;
 static const int32_t DATA_VERSION = 2730; /* Java Edition 1.17.1; includes copper ore. */
 static const block_state BLOCK_STATE_TABLE[] = {
@@ -154,7 +156,17 @@ static const block_state BLOCK_STATE_TABLE[] = {
 	[BLOCK_STONE_BRICK_STAIRS_E] = {"minecraft:stone_brick_stairs", PROPS_STAIRS_E, 4},
 	[BLOCK_STONE_BRICK_STAIRS_W] = {"minecraft:stone_brick_stairs", PROPS_STAIRS_W, 4},
 	[BLOCK_STONE_BRICK_STAIRS_N] = {"minecraft:stone_brick_stairs", PROPS_STAIRS_N, 4},
-	[BLOCK_STONE_BRICK_STAIRS_S] = {"minecraft:stone_brick_stairs", PROPS_STAIRS_S, 4}
+	[BLOCK_STONE_BRICK_STAIRS_S] = {"minecraft:stone_brick_stairs", PROPS_STAIRS_S, 4},
+	[BLOCK_DANDELION] = {"minecraft:dandelion", NULL, 0},
+	[BLOCK_AZURE_BLUET] = {"minecraft:azure_bluet", NULL, 0},
+	[BLOCK_OXEYE_DAISY] = {"minecraft:oxeye_daisy", NULL, 0},
+	[BLOCK_CORNFLOWER] = {"minecraft:cornflower", NULL, 0},
+	[BLOCK_LILY_OF_THE_VALLEY] = {"minecraft:lily_of_the_valley", NULL, 0},
+	[BLOCK_FERN] = {"minecraft:fern", NULL, 0},
+	[BLOCK_CLAY] = {"minecraft:clay", NULL, 0},
+	[BLOCK_SEAGRASS] = {"minecraft:seagrass", NULL, 0},
+	[BLOCK_IRON_BARS_NS] = {"minecraft:iron_bars", PROPS_IRON_BARS_NS, 5},
+	[BLOCK_IRON_BARS_EW] = {"minecraft:iron_bars", PROPS_IRON_BARS_EW, 5}
 };
 
 static const block_state *get_block_state(uint16_t id) {
@@ -308,18 +320,18 @@ static int64_t to_signed64(uint64_t v) {
 
 static void pack_bits(const uint16_t *indices, size_t count, int bits_per_value, int64_t *out_longs, size_t out_count) {
 	memset(out_longs, 0, out_count * sizeof(int64_t));
+	int values_per_long = 64 / bits_per_value;
+	if (values_per_long < 1) values_per_long = 1;
 	for (size_t idx = 0; idx < count; ++idx) {
 		uint64_t value = indices[idx];
-		size_t bit_index = idx * (size_t)bits_per_value;
-		size_t long_id = bit_index / 64;
-		size_t offset = bit_index % 64;
+		size_t long_id = idx / (size_t)values_per_long;
+		size_t offset = (idx % (size_t)values_per_long) * (size_t)bits_per_value;
+		if (long_id >= out_count) continue;
 		uint64_t *target = (uint64_t *)&out_longs[long_id];
 		*target |= value << offset;
-		int spill = (int)(offset + bits_per_value - 64);
-		if (spill > 0 && long_id + 1 < out_count) {
-			uint64_t *next = (uint64_t *)&out_longs[long_id + 1];
-			*next |= value >> (bits_per_value - spill);
 	}
+	for (size_t i = 0; i < out_count; ++i) {
+		out_longs[i] = to_signed64((uint64_t)out_longs[i]);
 	}
 }
 
@@ -345,6 +357,13 @@ static void pack_heightmap(const chunk_data *chunk, int64_t *out_longs, size_t o
 	}
 }
 
+static int column_contains_water(const chunk_data *chunk, int x, int z) {
+	for (int y = 1; y < CHUNK_HEIGHT; ++y) {
+		if (chunk->blocks[y][x][z] == BLOCK_WATER) return 1;
+	}
+	return 0;
+}
+
 static int section_has_blocks(const chunk_data *chunk, int section_y) {
 	int y_base = section_y * 16;
 	for (int y = 0; y < 16; ++y) {
@@ -406,7 +425,9 @@ static void write_section(buf *b, const chunk_data *chunk, int section_y) {
 		int needed = (int)ceil(log2((double)palette_len));
 		if (needed > bits) bits = needed;
 	}
-	size_t packed_count = ((size_t)idx * (size_t)bits + 63) / 64;
+	size_t values_per_long = (size_t)(64 / bits);
+	if (values_per_long < 1) values_per_long = 1;
+	size_t packed_count = ((size_t)idx + values_per_long - 1) / values_per_long;
 	int64_t *packed = (int64_t *)calloc(packed_count, sizeof(int64_t));
 	if (!packed) return;
 	pack_bits(block_indices, idx, bits, packed, packed_count);
@@ -436,7 +457,11 @@ static void write_section(buf *b, const chunk_data *chunk, int section_y) {
 
 static void build_chunk_nbt(const chunk_data *chunk, buf *out) {
 	int32_t biomes[256];
-	for (int i = 0; i < 256; ++i) biomes[i] = 1;  // Plains biome
+	for (int z = 0; z < CHUNK_SIZE; ++z) {
+		for (int x = 0; x < CHUNK_SIZE; ++x) {
+			biomes[z * CHUNK_SIZE + x] = column_contains_water(chunk, x, z) ? 0 : 1; // Ocean or plains
+		}
+	}
 
 	int64_t heightmap[37];
 	pack_heightmap(chunk, heightmap, 37);

worldgen-c/src/worldgen.c

@@ -131,12 +131,14 @@ static inline double smoothstep01(double v) {
 }
 
 static int ground_slope(worldgen_ctx *ctx, int x, int z);
+static int is_dry_beach_sand_patch(worldgen_ctx *ctx, const column_data *data, int world_x, int world_z);
 static uint16_t select_surface_block(worldgen_ctx *ctx, const column_data *data, int world_x, int world_z);
 static void generate_chunk_trails(worldgen_ctx *ctx, int chunk_x, int chunk_z, column_data columns[CHUNK_SIZE][CHUNK_SIZE], chunk_data *out);
 static void generate_chunk_redwood_floor(worldgen_ctx *ctx, int chunk_x, int chunk_z,
 									 column_data columns[CHUNK_SIZE][CHUNK_SIZE], chunk_data *chunk);
 static void generate_chunk_grass(worldgen_ctx *ctx, int chunk_x, int chunk_z, column_data columns[CHUNK_SIZE][CHUNK_SIZE], chunk_data *out);
 static void generate_chunk_flowers(worldgen_ctx *ctx, int chunk_x, int chunk_z, column_data columns[CHUNK_SIZE][CHUNK_SIZE], chunk_data *out);
+static void generate_chunk_aquatic_life(worldgen_ctx *ctx, int chunk_x, int chunk_z, column_data columns[CHUNK_SIZE][CHUNK_SIZE], chunk_data *out);
 static void generate_chunk_cabins(worldgen_ctx *ctx, int chunk_x, int chunk_z, column_data columns[CHUNK_SIZE][CHUNK_SIZE], chunk_data *out);
 static void generate_chunk_border_wall(worldgen_ctx *ctx, int chunk_x, int chunk_z, chunk_data *out);
 static void ensure_trail_prepass(worldgen_ctx *ctx, int chunk_x, int chunk_z);
@@ -181,6 +183,13 @@ static uint32_t hash_coords3(int x, int y, int z, uint32_t seed) {
 	return h ^ (h >> 16);
 }
 
+static int floor_div_int(int value, int divisor) {
+	int q = value / divisor;
+	int r = value % divisor;
+	if (r != 0 && ((r < 0) != (divisor < 0))) q--;
+	return q;
+}
+
 static double land_value(worldgen_ctx *ctx, int x, int z) {
 	column_data col = get_column_data(ctx, x, z);
 	double value = 0.0;
@@ -684,6 +693,19 @@ static int raw_column_height(worldgen_ctx *ctx, int x, int z) {
 		height = height * (1.0 - plains_blend) + plains_target * plains_blend;
 	}
 
+	double above_water = height - (double)ctx->sea_level;
+	if (above_water > -1.5 && above_water < 24.0) {
+		double island_mask = smoothstep01((above_water + 1.5) / 6.0) * (1.0 - smoothstep01((above_water - 12.0) / 12.0));
+		island_mask *= 1.0 - build_flats * 0.7;
+		double rolling = simplex_noise2(&ctx->noise, (warp2_x + 76000) * 0.0045, (warp2_z - 76000) * 0.0045) * 3.2;
+		rolling += simplex_noise2(&ctx->noise, (warp2_x - 83000) * 0.013, (warp2_z + 83000) * 0.013) * 1.4;
+		double mound = simplex_noise2(&ctx->noise, (warp2_x + 91000) * 0.021, (warp2_z - 91000) * 0.021) * 0.5 + 0.5;
+		rolling += mound * mound * 2.0;
+		double coastal_mask = (1.0 - smoothstep01((above_water - 1.0) / 5.0)) * smoothstep01((above_water + 1.0) / 3.0);
+		double dune = fabs(simplex_noise2(&ctx->noise, (warp2_x - 47000) * 0.028, (warp2_z + 47000) * 0.028)) * 2.2;
+		height += (rolling * island_mask) + (dune * coastal_mask * (1.0 - build_flats * 0.85));
+	}
+
 	return (int)height;
 }
 
@@ -929,11 +951,51 @@ static int generate_coal(worldgen_ctx *ctx, int x, int y, int z, int column_heig
 // ---------------------------------------------------------------------------
 // Terrain block generation
 // ---------------------------------------------------------------------------
+static int is_dry_beach_sand_patch(worldgen_ctx *ctx, const column_data *data, int world_x, int world_z) {
+	if (data->has_water && data->water_surface >= data->height) return 0;
+	if (ground_slope(ctx, world_x, world_z) > 2) return 0;
+
+	int nearest_water_dist2 = 9999;
+	int shore_level = ctx->sea_level;
+	for (int dx = -7; dx <= 7; ++dx) {
+		for (int dz = -7; dz <= 7; ++dz) {
+			int dist2 = dx * dx + dz * dz;
+			if (dist2 == 0 || dist2 > 49) continue;
+			column_data neighbor = get_column_data(ctx, world_x + dx, world_z + dz);
+			if (!neighbor.has_water || neighbor.water_surface < neighbor.height) continue;
+			if (data->height < neighbor.water_surface - 1 || data->height > neighbor.water_surface + 4) continue;
+			if (dist2 < nearest_water_dist2) {
+				nearest_water_dist2 = dist2;
+				shore_level = neighbor.water_surface;
+			}
+		}
+	}
+	if (nearest_water_dist2 == 9999) return 0;
+	if (data->height > shore_level + 4) return 0;
+
+	double broad = simplex_noise2(&ctx->noise, (world_x + 72000) * 0.045, (world_z - 72000) * 0.045) * 0.5 + 0.5;
+	double ragged = simplex_noise2(&ctx->noise, (world_x - 81000) * 0.16, (world_z + 81000) * 0.16) * 0.5 + 0.5;
+	double patch = broad * 0.7 + ragged * 0.3;
+	double near_bonus = clamp01((18.0 - (double)nearest_water_dist2) / 18.0) * 0.18;
+	double height_penalty = clamp01((double)(data->height - shore_level) / 4.0) * 0.16;
+	return patch + near_bonus - height_penalty > 0.56;
+}
+
 static uint16_t select_surface_block(worldgen_ctx *ctx, const column_data *data, int world_x, int world_z) {
 	if (data->has_water && data->water_surface >= data->height) {
 		int slope = ground_slope(ctx, world_x, world_z);
-		if (slope <= 1) return BLOCK_SAND;
-		if (slope <= 3) return BLOCK_GRAVEL;
+		double shelf = simplex_noise2(&ctx->noise, (world_x + 45000) * 0.025, (world_z - 45000) * 0.025) * 0.5 + 0.5;
+		double basin = simplex_noise2(&ctx->noise, (world_x - 23000) * 0.007, (world_z + 23000) * 0.007) * 0.5 + 0.5;
+		int depth = data->water_surface - data->height;
+		if (slope <= 1) {
+			if (depth >= 3 && basin > 0.74) return BLOCK_CLAY;
+			if (shelf > 0.76) return BLOCK_GRAVEL;
+			return BLOCK_SAND;
+		}
+		if (slope <= 3) {
+			if (depth >= 4 && basin > 0.82) return BLOCK_CLAY;
+			return (shelf > 0.44) ? BLOCK_GRAVEL : BLOCK_SAND;
+		}
 		return BLOCK_STONE;
 	}
 	int snow_line = ctx->snow_line;
@@ -946,6 +1008,9 @@ static uint16_t select_surface_block(worldgen_ctx *ctx, const column_data *data,
 		double noise = simplex_noise2(&ctx->noise, world_x * 0.02, world_z * 0.02) * 0.5 + 0.5;
 		if (noise < t) return BLOCK_SNOW;
 	}
+	if (is_dry_beach_sand_patch(ctx, data, world_x, world_z)) {
+		return BLOCK_SAND;
+	}
 	if (data->biome == BIOME_REDWOOD_FOREST) {
 		int slope = ground_slope(ctx, world_x, world_z);
 		if (slope >= 5) return BLOCK_STONE;
@@ -1050,6 +1115,7 @@ static void place_leaf_circle(int cx, int cy, int cz, int radius, int leaf_block
 	int r2 = radius * radius;
 	for (int dx = -radius; dx <= radius; ++dx) {
 		for (int dz = -radius; dz <= radius; ++dz) {
+			if (dx == 0 && dz == 0) continue;
 			if (dx * dx + dz * dz > r2) continue;
 			if (hole_prob > 0.0 && rng_next_f64(rng) < hole_prob) continue;
 			block_list_push(out, cx + dx, cy, cz + dz, (uint16_t)leaf_block);
@@ -1579,6 +1645,33 @@ static void build_redwood_titan(worldgen_ctx *ctx, int x, int y, int z, int heig
 		{1, 0}, {-1, 0}, {0, 1}, {0, -1},
 		{1, 1}, {1, -1}, {-1, 1}, {-1, -1}
 	};
+	if (rng_next_f64(rng) < 0.10) {
+		int snag_height = core_height - rng_range_inclusive(rng, 4, 10);
+		if (snag_height < 22) snag_height = 22;
+		int taper_start = snag_height - 5;
+		for (int dy = 0; dy < snag_height; ++dy) {
+			int radius = (dy >= taper_start) ? 0 : 1;
+			for (int dx = -radius; dx <= radius; ++dx) {
+				for (int dz = -radius; dz <= radius; ++dz) {
+					if (radius == 1 && abs(dx) == 1 && abs(dz) == 1 && dy > 10 && (dy % 3) == 0) continue;
+					block_list_push(out, x + dx, y + dy, z + dz, (uint16_t)arch->log_block);
+				}
+			}
+			if (dy > 8 && dy < snag_height - 4 && (dy % 7) == 0) {
+				int dir = (dy / 7 + rng_range_inclusive(rng, 0, 3)) & 7;
+				int branch_log = redwood_axis_log(arch->log_block, dirs8[dir][0], dirs8[dir][1]);
+				int len = 2 + rng_range_inclusive(rng, 0, 2);
+				for (int step = 2; step <= len + 1; ++step) {
+					block_list_push(out, x + dirs8[dir][0] * step, y + dy, z + dirs8[dir][1] * step, (uint16_t)branch_log);
+				}
+			}
+		}
+		for (int i = 0; i < 6; ++i) {
+			int root_len = 3 + rng_range_inclusive(rng, 0, 2);
+			place_redwood_root(ctx, x, y, z, dirs8[i][0], dirs8[i][1], root_len, arch->log_block, rng, out);
+		}
+		return;
+	}
 	int spire = 3 + rng_range_inclusive(rng, 0, 2);
 	int crown_start = y + core_height / 2 + rng_range_inclusive(rng, 0, 2);
 
@@ -1863,7 +1956,7 @@ static void generate_chunk_redwood_floor(worldgen_ctx *ctx, int chunk_x, int chu
 			double litter = simplex_noise2(&ctx->noise, (wx + 8000) * 0.03, (wz - 8000) * 0.03) * 0.5 + 0.5;
 			double fern_chance = clamp01(0.25 + rain * 0.5 + (1.0 - litter) * 0.25);
 			if (chunk->blocks[cd.height + 1][dx][dz] == BLOCK_AIR && rng_next_f64(&rng) < fern_chance) {
-				chunk->blocks[cd.height + 1][dx][dz] = BLOCK_TALL_GRASS;
+				chunk->blocks[cd.height + 1][dx][dz] = (rain > 0.55 || rng_next_f64(&rng) < 0.45) ? BLOCK_FERN : BLOCK_TALL_GRASS;
 			}
 			if (rng_next_f64(&rng) < 0.0035) {
 				try_place_redwood_fallen_log(ctx, chunk_x, chunk_z, chunk, columns, dx, dz, &rng);
@@ -1894,7 +1987,7 @@ static void generate_chunk_grass(worldgen_ctx *ctx, int chunk_x, int chunk_z, co
 			uint32_t h = hash_coords(world_x, world_z, (uint32_t)(ctx->world_seed ^ 0x5F3759DFu));
 			double roll = (double)(h & 0xFFFF) / 65535.0;
 			if (roll > chance) continue;
-			out->blocks[cd.height + 1][dx][dz] = BLOCK_TALL_GRASS;
+			out->blocks[cd.height + 1][dx][dz] = (humidity > 0.72 && rain > 0.45) ? BLOCK_FERN : BLOCK_TALL_GRASS;
 			if (roll < chance * 0.4) {
 				const int offsets[4][2] = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
 				for (int i = 0; i < 4; ++i) {
@@ -1905,7 +1998,7 @@ static void generate_chunk_grass(worldgen_ctx *ctx, int chunk_x, int chunk_z, co
 					if (nd.height <= 0 || nd.height >= CHUNK_HEIGHT - 1) continue;
 					if (out->blocks[nd.height][nx][nz] != BLOCK_GRASS) continue;
 					if (out->blocks[nd.height + 1][nx][nz] != BLOCK_AIR) continue;
-					out->blocks[nd.height + 1][nx][nz] = BLOCK_TALL_GRASS;
+					out->blocks[nd.height + 1][nx][nz] = ((h >> (i + 3)) & 1u) ? BLOCK_TALL_GRASS : BLOCK_FERN;
 				}
 			}
 		}
@@ -1935,7 +2028,17 @@ static void generate_chunk_flowers(worldgen_ctx *ctx, int chunk_x, int chunk_z,
 			uint32_t h = hash_coords(world_x + 30000, world_z - 30000, (uint32_t)(ctx->world_seed ^ 0xA511E9B5u));
 			double roll = (double)(h & 0xFFFF) / 65535.0;
 			if (roll > chance) continue;
-			out->blocks[cd.height + 1][dx][dz] = BLOCK_WILDFLOWER;
+			uint16_t flower = BLOCK_WILDFLOWER;
+			uint32_t flower_hash = hash_coords(world_x - 17000, world_z + 17000, (uint32_t)(ctx->world_seed ^ 0xB10F00Du));
+			switch ((flower_hash >> 8) % 6) {
+				case 0: flower = BLOCK_DANDELION; break;
+				case 1: flower = BLOCK_AZURE_BLUET; break;
+				case 2: flower = BLOCK_OXEYE_DAISY; break;
+				case 3: flower = BLOCK_CORNFLOWER; break;
+				case 4: flower = BLOCK_LILY_OF_THE_VALLEY; break;
+				default: flower = BLOCK_WILDFLOWER; break;
+			}
+			out->blocks[cd.height + 1][dx][dz] = flower;
 			static const int offsets[4][2] = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
 			for (int i = 0; i < 4; ++i) {
 				int nx = dx + offsets[i][0];
@@ -1947,7 +2050,40 @@ static void generate_chunk_flowers(worldgen_ctx *ctx, int chunk_x, int chunk_z,
 				if (out->blocks[nd.height + 1][nx][nz] != BLOCK_AIR) continue;
 				uint32_t nh = hash_coords(world_x + offsets[i][0] + 60000, world_z + offsets[i][1] - 60000, (uint32_t)(ctx->world_seed ^ 0xF00DBAAu));
 				if ((nh & 0xFFFF) > 24000) continue;
-				out->blocks[nd.height + 1][nx][nz] = BLOCK_WILDFLOWER;
+				uint16_t patch_flower = flower;
+				if ((nh & 7u) == 0u) patch_flower = BLOCK_DANDELION;
+				out->blocks[nd.height + 1][nx][nz] = patch_flower;
+			}
+		}
+	}
+}
+
+static void generate_chunk_aquatic_life(worldgen_ctx *ctx, int chunk_x, int chunk_z, column_data columns[CHUNK_SIZE][CHUNK_SIZE], chunk_data *out) {
+	for (int dx = 0; dx < CHUNK_SIZE; ++dx) {
+		for (int dz = 0; dz < CHUNK_SIZE; ++dz) {
+			column_data cd = columns[dx][dz];
+			if (!cd.has_water || cd.water_surface <= cd.height) continue;
+			if (cd.height <= 0 || cd.height >= CHUNK_HEIGHT - 2) continue;
+			int depth = cd.water_surface - cd.height;
+			if (depth < 1 || depth > 9) continue;
+			int world_x = chunk_x * CHUNK_SIZE + dx;
+			int world_z = chunk_z * CHUNK_SIZE + dz;
+			uint16_t floor = out->blocks[cd.height][dx][dz];
+			if (floor != BLOCK_SAND && floor != BLOCK_GRAVEL && floor != BLOCK_CLAY && floor != BLOCK_DIRT) continue;
+			if (out->blocks[cd.height + 1][dx][dz] != BLOCK_WATER) continue;
+			double bed = simplex_noise2(&ctx->noise, (world_x + 70000) * 0.035, (world_z - 70000) * 0.035) * 0.5 + 0.5;
+			double patch = simplex_noise2(&ctx->noise, (world_x - 15000) * 0.011, (world_z + 15000) * 0.011) * 0.5 + 0.5;
+			double chance = 0.08 + patch * 0.24;
+			if (floor == BLOCK_CLAY) chance += 0.10;
+			if (depth <= 3) chance += 0.12;
+			if (ground_slope(ctx, world_x, world_z) > 2) chance *= 0.35;
+			uint32_t h = hash_coords(world_x, world_z, (uint32_t)(ctx->world_seed ^ 0x5EA6A55u));
+			double roll = (double)(h & 0xFFFF) / 65535.0;
+			if (roll > clamp01(chance)) continue;
+			out->blocks[cd.height + 1][dx][dz] = BLOCK_SEAGRASS;
+			if (depth >= 3 && bed > 0.78 && cd.height + 2 < CHUNK_HEIGHT &&
+			    out->blocks[cd.height + 2][dx][dz] == BLOCK_WATER) {
+				out->blocks[cd.height + 2][dx][dz] = BLOCK_SEAGRASS;
 			}
 		}
 	}
@@ -3554,6 +3690,99 @@ static void generate_chunk_trails(worldgen_ctx *ctx, int chunk_x, int chunk_z, c
 	}
 }
 
+static int border_wall_anchor_base(worldgen_ctx *ctx, int side, int anchor_along, int wall_center) {
+	int center_x = anchor_along;
+	int center_z = anchor_along;
+	switch (side) {
+		case 0:
+			center_x = ctx->wall_min_x + wall_center;
+			break;
+		case 1:
+			center_x = ctx->wall_max_x - wall_center;
+			break;
+		case 2:
+			center_z = ctx->wall_min_z + wall_center;
+			break;
+		case 3:
+			center_z = ctx->wall_max_z - wall_center;
+			break;
+	}
+
+	int smoothed_base = 0;
+	int weight_sum = 0;
+	int highest_sample_base = 0;
+	const int sample_offsets[5] = {-32, -16, 0, 16, 32};
+	const int sample_weights[5] = {1, 2, 4, 2, 1};
+	for (int i = 0; i < 5; ++i) {
+		int sx = center_x;
+		int sz = center_z;
+		if (side < 2) {
+			sz += sample_offsets[i];
+		} else {
+			sx += sample_offsets[i];
+		}
+		if (sx < ctx->wall_min_x) sx = ctx->wall_min_x;
+		if (sx > ctx->wall_max_x) sx = ctx->wall_max_x;
+		if (sz < ctx->wall_min_z) sz = ctx->wall_min_z;
+		if (sz > ctx->wall_max_z) sz = ctx->wall_max_z;
+		column_data sample = get_column_data(ctx, sx, sz);
+		int sample_base = sample.height;
+		if (sample.has_water && sample.water_surface > sample_base) sample_base = sample.water_surface;
+		if (i == 0 || sample_base > highest_sample_base) highest_sample_base = sample_base;
+		smoothed_base += sample_base * sample_weights[i];
+		weight_sum += sample_weights[i];
+	}
+	smoothed_base /= weight_sum;
+	if (highest_sample_base > smoothed_base + 8) {
+		smoothed_base += (highest_sample_base - smoothed_base - 8 + 1) / 2;
+	}
+	if (smoothed_base < 1) smoothed_base = 1;
+	if (smoothed_base > CHUNK_HEIGHT - 2) smoothed_base = CHUNK_HEIGHT - 2;
+	return smoothed_base;
+}
+
+static int border_wall_ramp_base(worldgen_ctx *ctx, int side, int along, int wall_center, int tower_spacing) {
+	int anchor = floor_div_int(along + tower_spacing / 2, tower_spacing) * tower_spacing;
+	int current_base = border_wall_anchor_base(ctx, side, anchor, wall_center);
+
+	int next_anchor = anchor + tower_spacing;
+	int next_boundary = anchor + tower_spacing / 2;
+	int next_base = border_wall_anchor_base(ctx, side, next_anchor, wall_center);
+	int next_delta = next_base - current_base;
+	if (next_delta != 0) {
+		int next_span = clamp_int(abs(next_delta), 6, tower_spacing - 8);
+		int next_start = next_boundary - next_span / 2;
+		int next_end = next_start + next_span;
+		if (along >= next_start && along <= next_end) {
+			int progress = along - next_start;
+			return current_base + (next_delta * progress + (next_delta > 0 ? next_span / 2 : -next_span / 2)) / next_span;
+		}
+	}
+
+	int prev_anchor = anchor - tower_spacing;
+	int prev_boundary = anchor - tower_spacing / 2;
+	int prev_base = border_wall_anchor_base(ctx, side, prev_anchor, wall_center);
+	int prev_delta = current_base - prev_base;
+	if (prev_delta != 0) {
+		int prev_span = clamp_int(abs(prev_delta), 6, tower_spacing - 8);
+		int prev_start = prev_boundary - prev_span / 2;
+		int prev_end = prev_start + prev_span;
+		if (along >= prev_start && along <= prev_end) {
+			int progress = along - prev_start;
+			return prev_base + (prev_delta * progress + (prev_delta > 0 ? prev_span / 2 : -prev_span / 2)) / prev_span;
+		}
+	}
+
+	return current_base;
+}
+
+static uint16_t border_wall_ramp_stair_block(int side, int slope) {
+	if (side < 2) {
+		return (slope > 0) ? BLOCK_STONE_BRICK_STAIRS_S : BLOCK_STONE_BRICK_STAIRS_N;
+	}
+	return (slope > 0) ? BLOCK_STONE_BRICK_STAIRS_E : BLOCK_STONE_BRICK_STAIRS_W;
+}
+
 static void generate_chunk_border_wall(worldgen_ctx *ctx, int chunk_x, int chunk_z, chunk_data *out) {
 	if (!ctx->enable_wall) return;
 	if (ctx->wall_min_x > ctx->wall_max_x || ctx->wall_min_z > ctx->wall_max_z) return;
@@ -3611,14 +3840,8 @@ static void generate_chunk_border_wall(worldgen_ctx *ctx, int chunk_x, int chunk
 			if (ladder_offset < 0) ladder_offset = -ladder_offset;
 			int near_corner = (dist_min_x < tower_depth || dist_max_x < tower_depth) &&
 			                  (dist_min_z < tower_depth || dist_max_z < tower_depth);
-			int ladder_module = !near_corner && ladder_offset <= 1;
-			int ladder_face = !near_corner && ladder_offset == 0 && side_dist == wall_end + 1;
-			int ladder_trim = ladder_module && side_dist == wall_end + 1 && ladder_offset == 1;
 			int in_tower = side_dist >= tower_outer && side_dist <= tower_inner &&
 			               (tower_offset <= tower_half_width || near_corner);
-			int in_wall = (side_dist >= wall_start && side_dist <= wall_end) || in_tower || ladder_face || ladder_trim;
-			int in_exterior_apron = side_dist < wall_start && !in_wall;
-			if (!in_wall && !in_exterior_apron) continue;
 
 			column_data data = get_column_data(ctx, world_x, world_z);
 			int visible_base = data.height;
@@ -3627,6 +3850,14 @@ static void generate_chunk_border_wall(worldgen_ctx *ctx, int chunk_x, int chunk
 			}
 			if (visible_base >= CHUNK_HEIGHT - 1) continue;
 
+			int dry_ladder_site = !(data.has_water && data.height < data.water_surface);
+			int ladder_module = !near_corner && dry_ladder_site && ladder_offset <= 1;
+			int ladder_face = ladder_module && ladder_offset == 0 && side_dist == wall_end + 1;
+			int ladder_trim = ladder_module && side_dist == wall_end + 1 && ladder_offset == 1;
+			int in_wall = (side_dist >= wall_start && side_dist <= wall_end) || in_tower || ladder_face || ladder_trim;
+			int in_exterior_apron = side_dist < wall_start && !in_wall;
+			if (!in_wall && !in_exterior_apron) continue;
+
 			if (in_exterior_apron) {
 				for (int y = data.height + 1; y < CHUNK_HEIGHT; ++y) {
 					out->blocks[y][dx][dz] = BLOCK_AIR;
@@ -3643,44 +3874,15 @@ static void generate_chunk_border_wall(worldgen_ctx *ctx, int chunk_x, int chunk
 				continue;
 			}
 
-			int center_x = world_x;
-			int center_z = world_z;
-			switch (side) {
-				case 0: center_x = ctx->wall_min_x + wall_center; break;
-				case 1: center_x = ctx->wall_max_x - wall_center; break;
-				case 2: center_z = ctx->wall_min_z + wall_center; break;
-				case 3: center_z = ctx->wall_max_z - wall_center; break;
+			int smoothed_base = border_wall_ramp_base(ctx, side, along, wall_center, tower_spacing);
+			int prev_base = border_wall_ramp_base(ctx, side, along - 1, wall_center, tower_spacing);
+			int next_base = border_wall_ramp_base(ctx, side, along + 1, wall_center, tower_spacing);
+			int stair_slope = 0;
+			if (next_base > smoothed_base) {
+				stair_slope = 1;
+			} else if (prev_base > smoothed_base) {
+				stair_slope = -1;
 			}
-			int smoothed_base = 0;
-			int weight_sum = 0;
-			const int sample_offsets[5] = {-32, -16, 0, 16, 32};
-			const int sample_weights[5] = {1, 2, 4, 2, 1};
-			for (int i = 0; i < 5; ++i) {
-				int sx = center_x;
-				int sz = center_z;
-				if (side < 2) {
-					sz += sample_offsets[i];
-				} else {
-					sx += sample_offsets[i];
-				}
-				if (sx < ctx->wall_min_x) sx = ctx->wall_min_x;
-				if (sx > ctx->wall_max_x) sx = ctx->wall_max_x;
-				if (sz < ctx->wall_min_z) sz = ctx->wall_min_z;
-				if (sz > ctx->wall_max_z) sz = ctx->wall_max_z;
-				column_data sample = get_column_data(ctx, sx, sz);
-				int sample_base = sample.height;
-				if (sample.has_water && sample.water_surface > sample_base) sample_base = sample.water_surface;
-				smoothed_base += sample_base * sample_weights[i];
-				weight_sum += sample_weights[i];
-			}
-			smoothed_base /= weight_sum;
-			if (visible_base > smoothed_base + 8) {
-				smoothed_base += (visible_base - smoothed_base - 8 + 3) / 4;
-			} else if (visible_base < smoothed_base - 16) {
-				smoothed_base -= (smoothed_base - visible_base - 16 + 4) / 5;
-			}
-			if (smoothed_base < 1) smoothed_base = 1;
-			if (smoothed_base > CHUNK_HEIGHT - 2) smoothed_base = CHUNK_HEIGHT - 2;
 
 			int height = in_tower ? tower_height : wall_height;
 			int top = smoothed_base + height;
@@ -3703,7 +3905,10 @@ static void generate_chunk_border_wall(worldgen_ctx *ctx, int chunk_x, int chunk
 				uint16_t block = BLOCK_SMOOTH_STONE;
 				int in_center_corridor = side_dist >= wall_center - 1 && side_dist <= wall_center + 1 &&
 				                         rel_y >= 2 && rel_y <= 4;
-				if (in_center_corridor) {
+				int in_walltop_tower_passage = in_tower &&
+				                              side_dist >= wall_center - 1 && side_dist <= wall_center + 1 &&
+				                              rel_y >= wall_height + 1 && rel_y <= wall_height + 3;
+				if (in_center_corridor || in_walltop_tower_passage) {
 					continue;
 				}
 				if (rel_y < 0) {
@@ -3715,7 +3920,10 @@ static void generate_chunk_border_wall(worldgen_ctx *ctx, int chunk_x, int chunk
 				if (side_dist >= wall_center - 1 && side_dist <= wall_center + 1 && rel_y == height) {
 					block = BLOCK_STONE_BRICKS;
 				}
-				if (ladder_face && rel_y >= 2 && rel_y <= height - 1) {
+				if (ladder_face && rel_y >= 2 && rel_y <= height) {
+					if (rel_y == height) {
+						continue;
+					}
 					block = ladder_block;
 				} else if (ladder_trim && rel_y >= 2 && rel_y <= height - 1 && rel_y % 3 != 1) {
 					block = (rel_y % 6 == 0) ? BLOCK_BLACKSTONE : BLOCK_STONE_BRICKS;
@@ -3730,12 +3938,19 @@ static void generate_chunk_border_wall(worldgen_ctx *ctx, int chunk_x, int chunk
 				}
 				set_block_with_height(out, dx, dz, y, block);
 			}
-			if (top + 1 < CHUNK_HEIGHT && (side_dist == wall_start || side_dist == wall_end || in_tower) &&
-			    phase % 4 < 2) {
+			if (top + 1 < CHUNK_HEIGHT) {
+				int rail_opening = ladder_module && side_dist == wall_end && ladder_offset <= 1;
+				if (side_dist >= wall_center - 1 && side_dist <= wall_center + 1 && stair_slope != 0) {
+					set_block_with_height(out, dx, dz, top + 1, border_wall_ramp_stair_block(side, stair_slope));
+				} else if (!in_tower && !rail_opening && (side_dist == wall_start || side_dist == wall_end)) {
+					uint16_t rail_block = (side < 2) ? BLOCK_IRON_BARS_NS : BLOCK_IRON_BARS_EW;
+					set_block_with_height(out, dx, dz, top + 1, rail_block);
+				} else if (in_tower && phase % 4 < 2) {
 					set_block_with_height(out, dx, dz, top + 1, BLOCK_STONE_BRICKS);
 				}
 			}
 		}
+	}
 }
 
 // ---------------------------------------------------------------------------
@@ -3805,7 +4020,15 @@ void worldgen_generate_chunk(worldgen_ctx *ctx, int chunk_x, int chunk_z, chunk_
 				out->blocks[y][dx][dz] = BLOCK_DIRT;
 			}
 			if (cd.height >= 0 && cd.height < CHUNK_HEIGHT) {
-				out->blocks[cd.height][dx][dz] = select_surface_block(ctx, &cd, world_x, world_z);
+				uint16_t surface = select_surface_block(ctx, &cd, world_x, world_z);
+				if (surface == BLOCK_SAND) {
+					int sand_bottom = cd.height - 2;
+					if (sand_bottom < dirt_start) sand_bottom = dirt_start;
+					for (int y = sand_bottom; y < cd.height; ++y) {
+						if (y > 0 && y < CHUNK_HEIGHT) out->blocks[y][dx][dz] = BLOCK_SAND;
+					}
+				}
+				out->blocks[cd.height][dx][dz] = surface;
 			}
 			if (cd.has_water) {
 				int water_top = cd.water_surface;
@@ -3824,6 +4047,7 @@ void worldgen_generate_chunk(worldgen_ctx *ctx, int chunk_x, int chunk_z, chunk_
 	generate_chunk_redwood_floor(ctx, chunk_x, chunk_z, columns, out);
 	generate_chunk_grass(ctx, chunk_x, chunk_z, columns, out);
 	generate_chunk_flowers(ctx, chunk_x, chunk_z, columns, out);
+	generate_chunk_aquatic_life(ctx, chunk_x, chunk_z, columns, out);
 
 	// Tree overlay
 	block_list trees;