Mgv7/flat/fractal: Place biome top node on tunnel entrance floor

1 files changed, 30 insertions, 11 deletions

diff --git a/src/mapgen_flat.cpp b/src/mapgen_flat.cpp
index c961d755a..b7f01320f 100644
--- a/src/mapgen_flat.cpp
+++ b/src/mapgen_flat.cpp
@@ -551,20 +551,39 @@ void MapgenFlat::dustTopNodes()
 void MapgenFlat::generateCaves(s16 max_stone_y)
 {
 	if (max_stone_y >= node_min.Y) {
-		u32 index = 0;
+		v3s16 em = vm->m_area.getExtent();
+		u32 index2d = 0;
+		u32 index3d;
 
 		for (s16 z = node_min.Z; z <= node_max.Z; z++)
-		for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
-			u32 vi = vm->m_area.index(node_min.X, y, z);
-			for (s16 x = node_min.X; x <= node_max.X; x++, vi++, index++) {
-				float d1 = contour(noise_cave1->result[index]);
-				float d2 = contour(noise_cave2->result[index]);
-				if (d1 * d2 > 0.3f) {
-					content_t c = vm->m_data[vi].getContent();
-					if (!ndef->get(c).is_ground_content || c == CONTENT_AIR)
-						continue;
-
+		for (s16 x = node_min.X; x <= node_max.X; x++, index2d++) {
+			bool open = false;  // Is column open to overground
+			u32 vi = vm->m_area.index(x, node_max.Y + 1, z);
+			index3d = (z - node_min.Z) * zstride + (csize.Y + 1) * ystride +
+				(x - node_min.X);
+			// Biome of column
+			Biome *biome = (Biome *)bmgr->getRaw(biomemap[index2d]);
+
+			for (s16 y = node_max.Y + 1; y >= node_min.Y - 1;
+					y--, index3d -= ystride, vm->m_area.add_y(em, vi, -1)) {
+				content_t c = vm->m_data[vi].getContent();
+				if (c == CONTENT_AIR || c == biome->c_water_top ||
+						c == biome->c_water) {
+					open = true;
+					continue;
+				}
+				// Ground
+				float d1 = contour(noise_cave1->result[index3d]);
+				float d2 = contour(noise_cave2->result[index3d]);
+				if (d1 * d2 > 0.3f && ndef->get(c).is_ground_content) {
+					// In tunnel and ground content, excavate
 					vm->m_data[vi] = MapNode(CONTENT_AIR);
+				} else if (open && (c == biome->c_filler || c == biome->c_stone)) {
+					// Tunnel entrance floor
+					vm->m_data[vi] = MapNode(biome->c_top);
+					open = false;
+				} else {
+					open = false;
 				}
 			}
 		}