Address border wall issue reports

worldgen-c/src/worldgen.c

@@ -181,6 +181,13 @@ 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;
@@ -3611,14 +3618,8 @@ 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 +3628,14 @@ 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;
@@ -3645,14 +3654,28 @@ static void generate_chunk_border_wall(worldgen_ctx *ctx, int chunk_x, int chunk
 
 			int center_x = world_x;
 			int center_z = world_z;
+			int base_along = (floor_div_int(along, tower_spacing) * tower_spacing) + tower_spacing / 2;
 			switch (side) {
-				case 0: center_x = ctx->wall_min_x + wall_center; break;
+				case 0:
-				case 1: center_x = ctx->wall_max_x - wall_center; break;
+					center_x = ctx->wall_min_x + wall_center;
-				case 2: center_z = ctx->wall_min_z + wall_center; break;
+					center_z = base_along;
-				case 3: center_z = ctx->wall_max_z - wall_center; break;
+					break;
+				case 1:
+					center_x = ctx->wall_max_x - wall_center;
+					center_z = base_along;
+					break;
+				case 2:
+					center_x = base_along;
+					center_z = ctx->wall_min_z + wall_center;
+					break;
+				case 3:
+					center_x = base_along;
+					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) {
@@ -3670,14 +3693,13 @@ static void generate_chunk_border_wall(worldgen_ctx *ctx, int chunk_x, int chunk
 				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 (visible_base > smoothed_base + 8) {
+			if (highest_sample_base > smoothed_base + 8) {
-				smoothed_base += (visible_base - smoothed_base - 8 + 3) / 4;
+				smoothed_base += (highest_sample_base - smoothed_base - 8 + 1) / 2;
-			} 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;
@@ -3715,7 +3737,10 @@ 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 +3755,15 @@ 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) &&
+			if (top + 1 < CHUNK_HEIGHT) {
-			    phase % 4 < 2) {
+				if (!in_tower && (side_dist == wall_start || side_dist == wall_end)) {
+					set_block_with_height(out, dx, dz, top + 1, BLOCK_IRON_BARS);
+				} else if (in_tower && phase % 4 < 2) {
 					set_block_with_height(out, dx, dz, top + 1, BLOCK_STONE_BRICKS);
 				}
 			}
 		}
+	}
 }
 
 // ---------------------------------------------------------------------------