Dungeons: Use biome 'node_stone' if normal stone types not detected

Construct dungeons from the node defined as biome 'node_stone' if
'mapgen_stone', 'mapgen_desert_stone' and 'mapgen_sandstone' are not
detected.
Feature long-intended by kwolekr/hmmmm and present in code as a TODO.

src/mapgen.cpp

@@ -621,7 +621,8 @@ MapgenBasic::~MapgenBasic()
 }
 
 
-MgStoneType MapgenBasic::generateBiomes(s16 biome_zero_level)
+void MapgenBasic::generateBiomes(MgStoneType *mgstone_type,
+	content_t *biome_stone, s16 biome_zero_level)
 {
 	// can't generate biomes without a biome generator!
 	assert(biomegen);
@@ -629,7 +630,8 @@ MgStoneType MapgenBasic::generateBiomes(s16 biome_zero_level)
 
 	const v3s16 &em = vm->m_area.getExtent();
 	u32 index = 0;
-	MgStoneType stone_type = MGSTONE_STONE;
+	MgStoneType stone_type = MGSTONE_OTHER;
+	content_t c_biome_stone = c_stone;
 
 	noise_filler_depth->perlinMap2D(node_min.X, node_min.Z);
 
@@ -689,12 +691,15 @@ MgStoneType MapgenBasic::generateBiomes(s16 biome_zero_level)
 				depth_riverbed = biome->depth_riverbed;
 
 				// Detect stone type for dungeons during every biome calculation.
-				// This is more efficient than detecting per-node and will not
+				// If none detected the last selected biome stone is chosen.
-				// miss any desert stone or sandstone biomes.
+				if (biome->c_stone == c_stone)
-				if (biome->c_stone == c_desert_stone)
+					stone_type = MGSTONE_STONE;
+				else if (biome->c_stone == c_desert_stone)
 					stone_type = MGSTONE_DESERT_STONE;
 				else if (biome->c_stone == c_sandstone)
 					stone_type = MGSTONE_SANDSTONE;
+
+				c_biome_stone = biome->c_stone;
 			}
 
 			if (c == c_stone) {
@@ -755,7 +760,8 @@ MgStoneType MapgenBasic::generateBiomes(s16 biome_zero_level)
 		}
 	}
 
-	return stone_type;
+	*mgstone_type = stone_type;
+	*biome_stone = c_biome_stone;
 }
 
 
@@ -845,7 +851,8 @@ bool MapgenBasic::generateCaverns(s16 max_stone_y)
 }
 
 
-void MapgenBasic::generateDungeons(s16 max_stone_y, MgStoneType stone_type)
+void MapgenBasic::generateDungeons(s16 max_stone_y,
+	MgStoneType stone_type, content_t biome_stone)
 {
 	if (max_stone_y < node_min.Y)
 		return;
@@ -908,6 +915,19 @@ void MapgenBasic::generateDungeons(s16 max_stone_y, MgStoneType stone_type)
 		dp.room_size_large_max = v3s16(18, 16, 18);
 		dp.notifytype          = GENNOTIFY_DUNGEON;
 		break;
+	case MGSTONE_OTHER:
+		dp.c_wall              = biome_stone;
+		dp.c_alt_wall          = biome_stone;
+		dp.c_stair             = biome_stone;
+
+		dp.diagonal_dirs       = false;
+		dp.holesize            = v3s16(1, 2, 1);
+		dp.room_size_min       = v3s16(4, 4, 4);
+		dp.room_size_max       = v3s16(8, 6, 8);
+		dp.room_size_large_min = v3s16(8, 8, 8);
+		dp.room_size_large_max = v3s16(16, 16, 16);
+		dp.notifytype          = GENNOTIFY_DUNGEON;
+		break;
 	}
 
 	DungeonGen dgen(ndef, &gennotify, &dp);

src/mapgen.h

@@ -79,11 +79,11 @@ enum GenNotifyType {
 	NUM_GENNOTIFY_TYPES
 };
 
-// TODO(hmmmm/paramat): make stone type selection dynamic
 enum MgStoneType {
 	MGSTONE_STONE,
 	MGSTONE_DESERT_STONE,
 	MGSTONE_SANDSTONE,
+	MGSTONE_OTHER,
 };
 
 struct GenNotifyEvent {
@@ -250,8 +250,10 @@ public:
 
 	virtual void generateCaves(s16 max_stone_y, s16 large_cave_depth);
 	virtual bool generateCaverns(s16 max_stone_y);
-	virtual void generateDungeons(s16 max_stone_y, MgStoneType stone_type);
+	virtual void generateDungeons(s16 max_stone_y,
-	virtual MgStoneType generateBiomes(s16 biome_zero_level = 0);
+		MgStoneType stone_type, content_t biome_stone);
+	virtual void generateBiomes(MgStoneType *mgstone_type,
+		content_t *biome_stone, s16 biome_zero_level);
 	virtual void dustTopNodes();
 
 protected:

src/mapgen_carpathian.cpp

@@ -242,7 +242,10 @@ void MapgenCarpathian::makeChunk(BlockMakeData *data)
 
 	// Init biome generator, place biome-specific nodes, and build biomemap
 	biomegen->calcBiomeNoise(node_min);
-	MgStoneType stone_type = generateBiomes(water_level - 1);
+
+	MgStoneType mgstone_type;
+	content_t biome_stone;
+	generateBiomes(&mgstone_type, &biome_stone, water_level - 1);
 
 	// Generate caverns, tunnels and classic caves
 	if (flags & MG_CAVES) {
@@ -262,7 +265,7 @@ void MapgenCarpathian::makeChunk(BlockMakeData *data)
 
 	// Generate dungeons
 	if (flags & MG_DUNGEONS)
-		generateDungeons(stone_surface_max_y, stone_type);
+		generateDungeons(stone_surface_max_y, mgstone_type, biome_stone);
 
 	// Generate the registered decorations
 	if (flags & MG_DECORATIONS)

src/mapgen_flat.cpp

@@ -189,13 +189,16 @@ void MapgenFlat::makeChunk(BlockMakeData *data)
 
 	// Init biome generator, place biome-specific nodes, and build biomemap
 	biomegen->calcBiomeNoise(node_min);
-	MgStoneType stone_type = generateBiomes(water_level - 1);
+
+	MgStoneType mgstone_type;
+	content_t biome_stone;
+	generateBiomes(&mgstone_type, &biome_stone, water_level - 1);
 
 	if (flags & MG_CAVES)
 		generateCaves(stone_surface_max_y, large_cave_depth);
 
 	if (flags & MG_DUNGEONS)
-		generateDungeons(stone_surface_max_y, stone_type);
+		generateDungeons(stone_surface_max_y, mgstone_type, biome_stone);
 
 	// Generate the registered decorations
 	if (flags & MG_DECORATIONS)

src/mapgen_fractal.cpp

@@ -200,13 +200,16 @@ void MapgenFractal::makeChunk(BlockMakeData *data)
 
 	// Init biome generator, place biome-specific nodes, and build biomemap
 	biomegen->calcBiomeNoise(node_min);
-	MgStoneType stone_type = generateBiomes(water_level - 1);
+
+	MgStoneType mgstone_type;
+	content_t biome_stone;
+	generateBiomes(&mgstone_type, &biome_stone, water_level - 1);
 
 	if (flags & MG_CAVES)
 		generateCaves(stone_surface_max_y, large_cave_depth);
 
 	if (flags & MG_DUNGEONS)
-		generateDungeons(stone_surface_max_y, stone_type);
+		generateDungeons(stone_surface_max_y, mgstone_type, biome_stone);
 
 	// Generate the registered decorations
 	if (flags & MG_DECORATIONS)

src/mapgen_v5.cpp

@@ -200,7 +200,10 @@ void MapgenV5::makeChunk(BlockMakeData *data)
 
 	// Init biome generator, place biome-specific nodes, and build biomemap
 	biomegen->calcBiomeNoise(node_min);
-	MgStoneType stone_type = generateBiomes(water_level - 1);
+
+	MgStoneType mgstone_type;
+	content_t biome_stone;
+	generateBiomes(&mgstone_type, &biome_stone, water_level - 1);
 
 	// Generate caverns, tunnels and classic caves
 	if (flags & MG_CAVES) {
@@ -220,7 +223,7 @@ void MapgenV5::makeChunk(BlockMakeData *data)
 
 	// Generate dungeons and desert temples
 	if (flags & MG_DUNGEONS)
-		generateDungeons(stone_surface_max_y, stone_type);
+		generateDungeons(stone_surface_max_y, mgstone_type, biome_stone);
 
 	// Generate the registered decorations
 	if (flags & MG_DECORATIONS)

src/mapgen_v7.cpp

@@ -308,7 +308,10 @@ void MapgenV7::makeChunk(BlockMakeData *data)
 
 	// Init biome generator, place biome-specific nodes, and build biomemap
 	biomegen->calcBiomeNoise(node_min);
-	MgStoneType stone_type = generateBiomes(biome_zero_level);
+
+	MgStoneType mgstone_type;
+	content_t biome_stone;
+	generateBiomes(&mgstone_type, &biome_stone, water_level - 1);
 
 	// Generate caverns, tunnels and classic caves
 	if (flags & MG_CAVES) {
@@ -328,7 +331,7 @@ void MapgenV7::makeChunk(BlockMakeData *data)
 
 	// Generate dungeons
 	if (flags & MG_DUNGEONS)
-		generateDungeons(stone_surface_max_y, stone_type);
+		generateDungeons(stone_surface_max_y, mgstone_type, biome_stone);
 
 	// Generate the registered decorations
 	if (flags & MG_DECORATIONS)

src/mapgen_valleys.cpp

@@ -236,7 +236,9 @@ void MapgenValleys::makeChunk(BlockMakeData *data)
 	updateHeightmap(node_min, node_max);
 
 	// Place biome-specific nodes and build biomemap
-	MgStoneType stone_type = generateBiomes(water_level - 1);
+	MgStoneType mgstone_type;
+	content_t biome_stone;
+	generateBiomes(&mgstone_type, &biome_stone, water_level - 1);
 
 	// Cave creation.
 	if (flags & MG_CAVES)
@@ -244,7 +246,7 @@ void MapgenValleys::makeChunk(BlockMakeData *data)
 
 	// Dungeon creation
 	if ((flags & MG_DUNGEONS) && node_max.Y < 50)
-		generateDungeons(stone_surface_max_y, stone_type);
+		generateDungeons(stone_surface_max_y, mgstone_type, biome_stone);
 
 	// Generate the registered decorations
 	if (flags & MG_DECORATIONS)