MgV5/6/7: Generate dungeons above water level

Use/add stone_surface_max_y to speed-optimise/guide dungeon generation
MgV7: Don't let mountain terrain chop dungeons at mapchunk borders
Make mountain terrain update stone_surface_max_y for caves in mountains

src/dungeongen.cpp

@@ -70,10 +70,7 @@ DungeonGen::DungeonGen(Mapgen *mapgen, DungeonParams *dparams) {
 
 void DungeonGen::generate(u32 bseed, v3s16 nmin, v3s16 nmax) {
 	//TimeTaker t("gen dungeons");
-	int approx_groundlevel = 10 + mg->water_level;
-
-	if ((nmin.Y + nmax.Y) / 2 >= approx_groundlevel ||
-		NoisePerlin3D(&dp.np_rarity, nmin.X, nmin.Y, nmin.Z, mg->seed) < 0.2)
+	if (NoisePerlin3D(&dp.np_rarity, nmin.X, nmin.Y, nmin.Z, mg->seed) < 0.2)
 		return;
 
 	this->blockseed = bseed;

src/mapgen_v5.cpp

@@ -252,7 +252,8 @@ void MapgenV5::makeChunk(BlockMakeData *data)
 	calculateNoise();
 
 	// Generate base terrain
-	generateBaseTerrain();
+	s16 stone_surface_max_y = generateBaseTerrain();
+
 	updateHeightmap(node_min, node_max);
 
 	// Generate underground dirt, sand, gravel and lava blobs
@@ -268,7 +269,7 @@ void MapgenV5::makeChunk(BlockMakeData *data)
 	generateBiomes();
 
 	// Generate dungeons and desert temples
-	if (flags & MG_DUNGEONS) {
+	if ((flags & MG_DUNGEONS) && (stone_surface_max_y >= node_min.Y)) {
 		DungeonGen dgen(this, NULL);
 		dgen.generate(blockseed, full_node_min, full_node_max);
 	}
@@ -342,10 +343,11 @@ void MapgenV5::calculateNoise()
 
 
 // Make base ground level
-void MapgenV5::generateBaseTerrain()
+int MapgenV5::generateBaseTerrain()
 {
 	u32 index = 0;
 	u32 index2d = 0;
+	int stone_surface_max_y = -MAP_GENERATION_LIMIT;
 
 	for(s16 z=node_min.Z; z<=node_max.Z; z++) {
 		for(s16 y=node_min.Y - 1; y<=node_max.Y + 1; y++) {
@@ -372,12 +374,16 @@ void MapgenV5::generateBaseTerrain()
 					vm->m_data[i] = MapNode(CONTENT_AIR);
 				} else {
 					vm->m_data[i] = MapNode(c_stone);
+					if (y > stone_surface_max_y)
+						stone_surface_max_y = y;
 				}
 			}
 			index2d = index2d - ystride;
 		}
 		index2d = index2d + ystride;
 	}
+
+	return stone_surface_max_y;
 }
 
 

src/mapgen_v5.h

@@ -94,7 +94,7 @@ public:
 	virtual void makeChunk(BlockMakeData *data);
 	int getGroundLevelAtPoint(v2s16 p);
 	void calculateNoise();
-	void generateBaseTerrain();
+	int generateBaseTerrain();
 	void generateBlobs();
 	void generateBiomes();
 	void dustTopNodes();

src/mapgen_v6.cpp

@@ -500,7 +500,7 @@ void MapgenV6::makeChunk(BlockMakeData *data)
 	}
 
 	// Add dungeons
-	if (flags & MG_DUNGEONS) {
+	if ((flags & MG_DUNGEONS) && (stone_surface_max_y >= node_min.Y)) {
 		DungeonParams dp;
 
 		dp.np_rarity  = nparams_dungeon_rarity;

src/mapgen_v7.cpp

@@ -241,7 +241,7 @@ void MapgenV7::makeChunk(BlockMakeData *data)
 	if (flags & MG_CAVES)
 		generateCaves(stone_surface_max_y);
 
-	if (flags & MG_DUNGEONS) {
+	if ((flags & MG_DUNGEONS) && (stone_surface_max_y >= node_min.Y)) {
 		DungeonGen dgen(this, NULL);
 		dgen.generate(blockseed, full_node_min, full_node_max);
 	}
@@ -405,7 +405,7 @@ int MapgenV7::generateTerrain()
 	int ymax = generateBaseTerrain();
 
 	if (spflags & MGV7_MOUNTAINS)
-		generateMountainTerrain();
+		ymax = generateMountainTerrain(ymax);
 
 	if (spflags & MGV7_RIDGES)
 		generateRidgeTerrain();
@@ -453,10 +453,10 @@ int MapgenV7::generateBaseTerrain()
 }
 
 
-void MapgenV7::generateMountainTerrain()
+int MapgenV7::generateMountainTerrain(int ymax)
 {
 	if (node_max.Y <= water_level)
-		return;
+		return ymax;
 
 	MapNode n_stone(c_stone);
 	u32 j = 0;
@@ -466,14 +466,21 @@ void MapgenV7::generateMountainTerrain()
 		u32 vi = vm->m_area.index(node_min.X, y, z);
 		for (s16 x = node_min.X; x <= node_max.X; x++) {
 			int index = (z - node_min.Z) * csize.X + (x - node_min.X);
+			content_t c = vm->m_data[vi].getContent();
 
-			if (getMountainTerrainFromMap(j, index, y))
+			if (getMountainTerrainFromMap(j, index, y)
+					&& (c == CONTENT_AIR || c == c_water_source)) {
 				vm->m_data[vi] = n_stone;
+				if (y > ymax)
+					ymax = y;
+			}
 
 			vi++;
 			j++;
 		}
 	}
+
+	return ymax;
 }
 
 

src/mapgen_v7.h

@@ -107,7 +107,7 @@ public:
 
 	virtual int generateTerrain();
 	int generateBaseTerrain();
-	void generateMountainTerrain();
+	int generateMountainTerrain(int ymax);
 	void generateRidgeTerrain();
 
 	void generateBiomes();