Tune tree density/spacing and fix trail distance to use segments

- nearest_trail_distance2 now measures point-to-segment distance to each
  trail edge instead of only to stored points, with a single-point fallback.
- Tree height scaling keeps canopy proportions; maturity adds subtle
  variation instead of shrinking young trees to bare poles.
- Raise forest spawn probability and tighten spacing for denser, more
  coherent stands; redwoods cluster a bit closer.
- Cabins near trails favor a wooded setback off the centerline; the spur
  still connects.

Co-Authored-By: Claude <noreply@anthropic.com>

README.md

@@ -64,6 +64,7 @@ Useful options:
 - `--sea-level L`: sea level, default `70`.
 - `--snow-line H`: snow threshold, default `sea-level + 38`.
 - `--trails`: enable trail and cabin prepass.
+- `--wall`: build a brutalist border wall around the generated area.
 - `--format mca|bin`: write Minecraft region files or raw debug chunks.
 - `--out DIR`: output directory.
 
@@ -73,11 +74,30 @@ Features
 - Redwoods are enabled automatically. The biome classifier marks high-rainfall,
   higher-relief areas as redwood forest, then places titan trees, dirt/mulch
   floor cover, tall grass, and occasional fallen logs.
+- General forests grow as broad, coherent oak, maple, birch, pine, spruce,
+  walnut, and cypress stands with occasional companion species. Seeded
+  clearings, sparse field trees, regenerating edges, mature interiors, variable
+  tree height, and irregular crown spacing keep the distribution from resolving
+  into a uniform grid.
 - Cabins are enabled automatically. With `--trails`, cabins only try to spawn on
   chunks crossed by the trail network so their spur paths can connect to roads.
   Without `--trails`, cabins can still spawn, but they are rarer and unconnected.
+- Cabin generation includes compact homesteads, longhouses, two-story houses,
+  L-shaped cabins, cross-gabled lodges, mixed-height tower lodges, and rambling
+  multi-wing cabins. Roof direction, wing height, material palette, windows,
+  porches, chimneys, decay, and path width vary by design.
+- Seeded woodland-community regions raise the local cabin frequency and give
+  their roads permission to bridge narrowly bounded water at exact sea level.
+  Eligible crossings must have nearby dry banks on both sides; deep water,
+  broad lakes, and open ocean remain impassable. Bridges use raised spruce
+  decks, timber supports, and intermittent edge posts rather than gravel fill.
 - Trails are optional because they need a prepass over the target area. Use
   `--trails` when you want roads and better-connected cabins.
+- Long roads search a broad terrain corridor and prefer valley floors, gentle
+  contour-following grades, low ridge crossings, and stable side slopes. Deep
+  water remains impassable; shallow water is crossed only when the detour cost
+  is greater, keeping fords and causeways short. Short cabin spurs use looser
+  engineering constraints so they can still reach the main network.
 
 Minecraft Version
 -----------------

worldgen-c/include/worldgen.h

@@ -7,6 +7,7 @@
 
 #define CHUNK_SIZE 16
 #define CHUNK_HEIGHT 256
+#define WORLDGEN_HEIGHT_CACHE_SIZE 32768
 
 	enum BlockId {
 		BLOCK_BEDROCK = 0,
@@ -52,7 +53,27 @@
 		BLOCK_LADDER_N = 40,
 		BLOCK_LADDER_S = 41,
 		BLOCK_LADDER_W = 42,
-		BLOCK_LADDER_E = 43
+		BLOCK_LADDER_E = 43,
+		BLOCK_SMOOTH_STONE = 44,
+		BLOCK_STONE_BRICKS = 45,
+		BLOCK_BLACKSTONE = 46,
+		BLOCK_IRON_BARS = 47,
+		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_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,
+		BLOCK_SPRUCE_STAIRS_N = 62,
+		BLOCK_SPRUCE_STAIRS_S = 63
 	};
 
 struct trail_segment;
@@ -64,17 +85,27 @@ typedef struct {
 	uint16_t blocks[CHUNK_HEIGHT][CHUNK_SIZE][CHUNK_SIZE];
 } chunk_data;
 
+typedef struct {
+	int x;
+	int z;
+	int value;
+	uint8_t valid;
+} worldgen_height_cache_entry;
+
 typedef struct {
 	simplex_noise noise;
 	int sea_level;
 	int world_seed;
 	int enable_trails;
+	int enable_wall;
+	int wall_min_x, wall_max_x, wall_min_z, wall_max_z;
 	int snow_line;
 	struct trail_segment *trail_segments;
 	size_t trail_segment_count;
 	size_t trail_segment_cap;
 	int prepass_done;
 	int prepass_min_x, prepass_max_x, prepass_min_z, prepass_max_z;
+	worldgen_height_cache_entry height_cache[WORLDGEN_HEIGHT_CACHE_SIZE];
 } worldgen_ctx;
 
 void worldgen_init(worldgen_ctx *ctx, int world_seed, int sea_level, int snow_line);
@@ -83,5 +114,7 @@ void worldgen_prepass(worldgen_ctx *ctx, int min_x, int max_x, int min_z, int ma
 void worldgen_free_trails(worldgen_ctx *ctx);
 int worldgen_debug_biome(worldgen_ctx *ctx, int x, int z);
 double worldgen_debug_redwood_mask(worldgen_ctx *ctx, int x, int z);
+double worldgen_debug_community_strength(worldgen_ctx *ctx, int x, int z);
+int worldgen_debug_bridge_site(worldgen_ctx *ctx, int x, int z, int dir_x, int dir_z);
 
 #endif

worldgen-c/src/main.c

@@ -51,6 +51,8 @@ typedef struct {
 	int snow_line;
 	pthread_mutex_t *log_mu;
 	int enable_trails;
+	int enable_wall;
+	int wall_min_x, wall_max_x, wall_min_z, wall_max_z;
 	results_buffer *results;
 	struct trail_segment *trail_segments;
 	size_t trail_segment_count;
@@ -84,6 +86,8 @@ static const kv_pair PROPS_WATER[] = {{"level", "0"}};
 static const kv_pair PROPS_LEAVES[] = {{"distance", "1"}, {"persistent", "false"}};
 static const kv_pair PROPS_STAIRS_E[] = {{"facing", "east"}, {"half", "bottom"}, {"shape", "straight"}, {"waterlogged", "false"}};
 static const kv_pair PROPS_STAIRS_W[] = {{"facing", "west"}, {"half", "bottom"}, {"shape", "straight"}, {"waterlogged", "false"}};
+static const kv_pair PROPS_STAIRS_N[] = {{"facing", "north"}, {"half", "bottom"}, {"shape", "straight"}, {"waterlogged", "false"}};
+static const kv_pair PROPS_STAIRS_S[] = {{"facing", "south"}, {"half", "bottom"}, {"shape", "straight"}, {"waterlogged", "false"}};
 static const kv_pair PROPS_DOOR_S_LOWER[] = {{"facing", "south"}, {"half", "lower"}, {"hinge", "left"}, {"open", "false"}, {"powered", "false"}};
 static const kv_pair PROPS_DOOR_S_UPPER[] = {{"facing", "south"}, {"half", "upper"}, {"hinge", "left"}, {"open", "false"}, {"powered", "false"}};
 static const kv_pair PROPS_DOOR_N_LOWER[] = {{"facing", "north"}, {"half", "lower"}, {"hinge", "left"}, {"open", "false"}, {"powered", "false"}};
@@ -96,6 +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[] = {
@@ -142,7 +148,27 @@ static const block_state BLOCK_STATE_TABLE[] = {
 	[BLOCK_LADDER_N] = {"minecraft:ladder", PROPS_LADDER_N, 2},
 	[BLOCK_LADDER_S] = {"minecraft:ladder", PROPS_LADDER_S, 2},
 	[BLOCK_LADDER_W] = {"minecraft:ladder", PROPS_LADDER_W, 2},
-	[BLOCK_LADDER_E] = {"minecraft:ladder", PROPS_LADDER_E, 2}
+	[BLOCK_LADDER_E] = {"minecraft:ladder", PROPS_LADDER_E, 2},
+	[BLOCK_SMOOTH_STONE] = {"minecraft:smooth_stone", NULL, 0},
+	[BLOCK_STONE_BRICKS] = {"minecraft:stone_bricks", NULL, 0},
+	[BLOCK_BLACKSTONE] = {"minecraft:blackstone", NULL, 0},
+	[BLOCK_IRON_BARS] = {"minecraft:iron_bars", NULL, 0},
+	[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_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},
+	[BLOCK_SPRUCE_STAIRS_N] = {"minecraft:spruce_stairs", PROPS_STAIRS_N, 4},
+	[BLOCK_SPRUCE_STAIRS_S] = {"minecraft:spruce_stairs", PROPS_STAIRS_S, 4}
 };
 
 static const block_state *get_block_state(uint16_t id) {
@@ -296,18 +322,18 @@ 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 = idx / (size_t)values_per_long;
-		size_t long_id = bit_index / 64;
+		size_t offset = (idx % (size_t)values_per_long) * (size_t)bits_per_value;
-		size_t offset = bit_index % 64;
+		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]);
 	}
 }
 
@@ -333,6 +359,13 @@ 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) {
@@ -394,7 +427,9 @@ 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);
@@ -424,7 +459,11 @@ 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);
@@ -593,7 +632,7 @@ static void write_regions(const char *out_dir, region_accum *regions, size_t reg
 static void usage(const char *prog) {
 	fprintf(stderr,
 	        "Usage: %s [--radius R] [--center-x X --center-z Z] [--min-x MX --max-x MX --min-z MZ --max-z MZ]\n"
-	        "          [--threads N] [--seed S] [--sea-level L] [--snow-line H] [--format mca|bin] [--trails] [--out DIR]\n",
+	        "          [--threads N] [--seed S] [--sea-level L] [--snow-line H] [--format mca|bin] [--trails] [--wall] [--out DIR]\n",
 	        prog);
 }
 
@@ -665,6 +704,11 @@ static void *worker_fn(void *ptr) {
 	worldgen_ctx ctx;
 	worldgen_init(&ctx, args->world_seed, args->sea_level, args->snow_line);
 	ctx.enable_trails = args->enable_trails;
+	ctx.enable_wall = args->enable_wall;
+	ctx.wall_min_x = args->wall_min_x;
+	ctx.wall_max_x = args->wall_max_x;
+	ctx.wall_min_z = args->wall_min_z;
+	ctx.wall_max_z = args->wall_max_z;
 	if (args->trail_segments && args->trail_segment_count > 0) {
 		ctx.trail_segments = args->trail_segments;
 		ctx.trail_segment_count = args->trail_segment_count;
@@ -682,14 +726,12 @@ static void *worker_fn(void *ptr) {
 		chunk_data chunk;
 		worldgen_generate_chunk(&ctx, job.x, job.z, &chunk);
 		if (args->results) {
-			pthread_mutex_lock(&args->results->mutex);
 			size_t result_idx = atomic_fetch_add(&args->results->count, 1);
 			if (result_idx < args->results->capacity) {
 				args->results->chunks[result_idx].chunk_x = chunk.chunk_x;
 				args->results->chunks[result_idx].chunk_z = chunk.chunk_z;
 				memcpy(&args->results->chunks[result_idx].data, &chunk, sizeof(chunk_data));
 			}
-			pthread_mutex_unlock(&args->results->mutex);
 		} else {
 			write_chunk_file(args->out_dir, &chunk);
 		}
@@ -716,6 +758,7 @@ int main(int argc, char **argv) {
 	int sea_level = 70;
 	int snow_line = INT_MIN;
 	int enable_trails = 0;
+	int enable_wall = 0;
 	const char *out_dir = "output";
 	output_format format = FORMAT_MCA;
 
@@ -761,6 +804,8 @@ int main(int argc, char **argv) {
 			}
 		} else if (strcmp(argv[i], "--trails") == 0) {
 			enable_trails = 1;
+		} else if (strcmp(argv[i], "--wall") == 0) {
+			enable_wall = 1;
 		} else if ((strcmp(argv[i], "--out") == 0 || strcmp(argv[i], "--output") == 0) && i + 1 < argc) {
 			out_dir = argv[++i];
 		} else if (strcmp(argv[i], "--help") == 0) {
@@ -791,6 +836,11 @@ int main(int argc, char **argv) {
 	int world_max_x = max_x * CHUNK_SIZE + (CHUNK_SIZE - 1);
 	int world_min_z = min_z * CHUNK_SIZE;
 	int world_max_z = max_z * CHUNK_SIZE + (CHUNK_SIZE - 1);
+	pre_ctx.enable_wall = enable_wall;
+	pre_ctx.wall_min_x = world_min_x;
+	pre_ctx.wall_max_x = world_max_x;
+	pre_ctx.wall_min_z = world_min_z;
+	pre_ctx.wall_max_z = world_max_z;
 	if (enable_trails) {
 		worldgen_prepass(&pre_ctx, world_min_x, world_max_x, world_min_z, world_max_z);
 		prepass_ready = 1;
@@ -836,6 +886,11 @@ int main(int argc, char **argv) {
 		.snow_line = snow_line,
 		.log_mu = &log_mu,
 		.enable_trails = enable_trails,
+		.enable_wall = enable_wall,
+		.wall_min_x = world_min_x,
+		.wall_max_x = world_max_x,
+		.wall_min_z = world_min_z,
+		.wall_max_z = world_max_z,
 		.results = &results,
 		.trail_segments = prepass_ready ? pre_ctx.trail_segments : NULL,
 		.trail_segment_count = prepass_ready ? pre_ctx.trail_segment_count : 0,

worldgen-c/tools/worldgen_scan.c

@@ -10,6 +10,7 @@ static int is_cabin_block(uint16_t block) {
 	       block == BLOCK_OAK_LOG_X || block == BLOCK_OAK_LOG_Z ||
 	       block == BLOCK_SPRUCE_LOG_X || block == BLOCK_SPRUCE_LOG_Z ||
 	       block == BLOCK_GLASS_PANE || block == BLOCK_GLASS || block == BLOCK_SPRUCE_STAIRS_E || block == BLOCK_SPRUCE_STAIRS_W ||
+	       block == BLOCK_SPRUCE_STAIRS_N || block == BLOCK_SPRUCE_STAIRS_S ||
 	       block == BLOCK_LADDER_N || block == BLOCK_LADDER_S || block == BLOCK_LADDER_E || block == BLOCK_LADDER_W ||
 	       block == BLOCK_SPRUCE_DOOR_N_LOWER || block == BLOCK_SPRUCE_DOOR_N_UPPER ||
 	       block == BLOCK_SPRUCE_DOOR_S_LOWER || block == BLOCK_SPRUCE_DOOR_S_UPPER ||
@@ -78,6 +79,8 @@ int main(int argc, char **argv) {
 	long cabin_columns = 0;
 	long gravel_columns = 0;
 	long cabin_gravel_columns = 0;
+	long bridge_deck_columns = 0;
+	long eligible_bridge_columns = 0;
 	long tall_log_columns = 0;
 	long max_oak_log_run = 0;
 	long biome_columns[4] = {0, 0, 0, 0};
@@ -96,8 +99,11 @@ int main(int argc, char **argv) {
 					if (biome >= 0 && biome < 4) ++biome_columns[biome];
 					double redwood_mask = worldgen_debug_redwood_mask(&ctx, wx, wz);
 					if (redwood_mask > max_redwood_mask) max_redwood_mask = redwood_mask;
+					if (worldgen_debug_bridge_site(&ctx, wx, wz, 1, 0) ||
+					    worldgen_debug_bridge_site(&ctx, wx, wz, 0, 1)) ++eligible_bridge_columns;
 					int has_cabin = 0;
 					int has_gravel = 0;
+					int has_bridge_deck = 0;
 					int current_run = 0;
 					int best_run = 0;
 					for (int y = 1; y < CHUNK_HEIGHT; ++y) {
@@ -109,6 +115,8 @@ int main(int argc, char **argv) {
 						if (block == BLOCK_GRAVEL) {
 							has_gravel = 1;
 						}
+						if (block == BLOCK_SPRUCE_PLANKS && y > 1 && chunk.blocks[y - 1][lx][lz] == BLOCK_WATER)
+							has_bridge_deck = 1;
 						if (block == BLOCK_OAK_LOG) {
 							++current_run;
 							if (current_run > best_run) best_run = current_run;
@@ -120,6 +128,7 @@ int main(int argc, char **argv) {
 					if (best_run >= 40) ++tall_log_columns;
 					if (has_cabin) ++cabin_columns;
 					if (has_gravel) ++gravel_columns;
+					if (has_bridge_deck) ++bridge_deck_columns;
 					if (has_cabin && has_gravel) {
 						++cabin_gravel_columns;
 					}
@@ -133,6 +142,8 @@ int main(int argc, char **argv) {
 	printf("cabin_columns=%ld\n", cabin_columns);
 	printf("gravel_columns=%ld\n", gravel_columns);
 	printf("cabin_gravel_columns=%ld\n", cabin_gravel_columns);
+	printf("bridge_deck_columns=%ld\n", bridge_deck_columns);
+	printf("eligible_bridge_columns=%ld\n", eligible_bridge_columns);
 	printf("tall_oak_log_columns=%ld\n", tall_log_columns);
 	printf("max_oak_log_run=%ld\n", max_oak_log_run);
 	printf("biome_west_ky=%ld\n", biome_columns[0]);