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

@@ -74,11 +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

@@ -71,7 +71,9 @@
 		BLOCK_CLAY = 58,
 		BLOCK_SEAGRASS = 59,
 		BLOCK_IRON_BARS_NS = 60,
-		BLOCK_IRON_BARS_EW = 61
+		BLOCK_IRON_BARS_EW = 61,
+		BLOCK_SPRUCE_STAIRS_N = 62,
+		BLOCK_SPRUCE_STAIRS_S = 63
 	};
 
 struct trail_segment;
@@ -112,5 +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

@@ -166,7 +166,9 @@ static const block_state BLOCK_STATE_TABLE[] = {
 	[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_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) {

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]);