Mgv7: Combine mountain terrain generation with base terrain generation

Previous mountain terrain generation was by necessity placing
stone in air, this was removing air from any overgenerated
structures such as tunnels, dungeons and large caves
Moving it into the base terrain generation loop ensures that
only 'ignore' is replaced

generateRidgeTerrain: only return if node_max.Y < water_level - 16
Previously, if water level was set a few nodes above a mapchunk
border the river channel was only partially excavated

src/mapgen_v7.cpp

@@ -59,6 +59,8 @@ MapgenV7::MapgenV7(int mapgenid, MapgenParams *params, EmergeManager *emerge)
 	//// amount of elements to skip for the next index
 	//// for noise/height/biome maps (not vmanip)
 	this->ystride = csize.X;
+	// 1-up 1-down overgeneration
+	this->zstride_1u1d = csize.X * (csize.Y + 2);
 	// 1-down overgeneration
 	this->zstride_1d = csize.X * (csize.Y + 1);
 
@@ -263,10 +265,13 @@ void MapgenV7::makeChunk(BlockMakeData *data)
 	// Make some noise
 	calculateNoise();
 
-	// Generate base terrain, mountains, and ridges with initial heightmaps
+	// Generate terrain and ridges with initial heightmaps
 	s16 stone_surface_max_y = generateTerrain();
 
-	// Create heightmap
+	if (spflags & MGV7_RIDGES)
+		generateRidgeTerrain();
+
+	// Update heightmap to include mountain terrain
 	updateHeightmap(node_min, node_max);
 
 	// Create biomemap at heightmap surface
@@ -361,6 +366,11 @@ void MapgenV7::calculateNoise()
 	noise_terrain_alt->perlinMap2D(x, z, persistmap);
 	noise_height_select->perlinMap2D(x, z);
 
+	if (spflags & MGV7_MOUNTAINS) {
+		noise_mountain->perlinMap3D(x, y, z);
+		noise_mount_height->perlinMap2D(x, z);
+	}
+
 	if ((spflags & MGV7_RIDGES) && node_max.Y >= water_level) {
 		noise_ridge->perlinMap3D(x, y, z);
 		noise_ridge_uwater->perlinMap2D(x, z);
@@ -369,9 +379,6 @@ void MapgenV7::calculateNoise()
 	// Cave noises are calculated in generateCaves()
 	// only if solid terrain is present in mapchunk
 
-	// Mountain noises are calculated in generateMountainTerrain()
-	// only if solid terrain surface dips into mapchunk
-
 	noise_filler_depth->perlinMap2D(x, z);
 	noise_heat->perlinMap2D(x, z);
 	noise_humidity->perlinMap2D(x, z);
@@ -400,7 +407,7 @@ Biome *MapgenV7::getBiomeAtPoint(v3s16 p)
 	return bmgr->getBiome(heat, humidity, groundlevel);
 }
 
-//needs to be updated
+
 float MapgenV7::baseTerrainLevelAtPoint(s16 x, s16 z)
 {
 	float hselect = NoisePerlin2D(&noise_height_select->np, x, z, seed);
@@ -455,100 +462,55 @@ bool MapgenV7::getMountainTerrainFromMap(int idx_xyz, int idx_xz, s16 y)
 
 
 int MapgenV7::generateTerrain()
-{
-	s16 stone_surface_min_y;
-	s16 stone_surface_max_y;
-
-	generateBaseTerrain(&stone_surface_min_y, &stone_surface_max_y);
-
-	if ((spflags & MGV7_MOUNTAINS) && stone_surface_min_y < node_max.Y)
-		stone_surface_max_y = generateMountainTerrain(stone_surface_max_y);
-
-	if (spflags & MGV7_RIDGES)
-		generateRidgeTerrain();
-
-	return stone_surface_max_y;
-}
-
-
-void MapgenV7::generateBaseTerrain(s16 *stone_surface_min_y, s16 *stone_surface_max_y)
 {
 	MapNode n_air(CONTENT_AIR);
 	MapNode n_stone(c_stone);
 	MapNode n_water(c_water_source);
 
 	v3s16 em = vm->m_area.getExtent();
-	s16 surface_min_y = MAX_MAP_GENERATION_LIMIT;
-	s16 surface_max_y = -MAX_MAP_GENERATION_LIMIT;
-	u32 index = 0;
+	s16 stone_surface_max_y = -MAX_MAP_GENERATION_LIMIT;
+	u32 index2d = 0;
+	bool mountain_flag = spflags & MGV7_MOUNTAINS;
 
 	for (s16 z = node_min.Z; z <= node_max.Z; z++)
-	for (s16 x = node_min.X; x <= node_max.X; x++, index++) {
-		float surface_height = baseTerrainLevelFromMap(index);
-		s16 surface_y = (s16)surface_height;
-
-		heightmap[index]       = surface_y;
-		ridge_heightmap[index] = surface_y;
-
-		if (surface_y < surface_min_y)
-			surface_min_y = surface_y;
+	for (s16 x = node_min.X; x <= node_max.X; x++, index2d++) {
+		s16 surface_y = baseTerrainLevelFromMap(index2d);
+		heightmap[index2d]       = surface_y;  // Create base terrain heightmap
+		ridge_heightmap[index2d] = surface_y;
 
-		if (surface_y > surface_max_y)
-			surface_max_y = surface_y;
+		if (surface_y > stone_surface_max_y)
+			stone_surface_max_y = surface_y;
 
 		u32 vi = vm->m_area.index(x, node_min.Y - 1, z);
+		u32 index3d = (z - node_min.Z) * zstride_1u1d + (x - node_min.X);
+
 		for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
 			if (vm->m_data[vi].getContent() == CONTENT_IGNORE) {
-				if (y <= surface_y)
-					vm->m_data[vi] = n_stone;
-				else if (y <= water_level)
+				if (y <= surface_y) {
+					vm->m_data[vi] = n_stone;  // Base terrain
+				} else if (mountain_flag &&
+						getMountainTerrainFromMap(index3d, index2d, y)) {
+					vm->m_data[vi] = n_stone;  // Mountain terrain
+					if (y > stone_surface_max_y)
+						stone_surface_max_y = y;
+				} else if (y <= water_level) {
 					vm->m_data[vi] = n_water;
-				else
+				} else {
 					vm->m_data[vi] = n_air;
+				}
 			}
 			vm->m_area.add_y(em, vi, 1);
+			index3d += ystride;
 		}
 	}
 
-	*stone_surface_min_y = surface_min_y;
-	*stone_surface_max_y = surface_max_y;
-}
-
-
-int MapgenV7::generateMountainTerrain(s16 ymax)
-{
-	noise_mountain->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
-	noise_mount_height->perlinMap2D(node_min.X, node_min.Z);
-
-	MapNode n_stone(c_stone);
-	u32 j = 0;
-
-	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++) {
-			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)
-					&& (c == CONTENT_AIR || c == c_water_source)) {
-				vm->m_data[vi] = n_stone;
-				if (y > ymax)
-					ymax = y;
-			}
-
-			vi++;
-			j++;
-		}
-	}
-
-	return ymax;
+	return stone_surface_max_y;
 }
 
 
 void MapgenV7::generateRidgeTerrain()
 {
-	if (node_max.Y < water_level)
+	if (node_max.Y < water_level - 16)
 		return;
 
 	MapNode n_water(c_water_source);
@@ -562,7 +524,7 @@ void MapgenV7::generateRidgeTerrain()
 		for (s16 x = node_min.X; x <= node_max.X; x++, index++, vi++) {
 			int j = (z - node_min.Z) * csize.X + (x - node_min.X);
 
-			if (heightmap[j] < water_level - 16)
+			if (heightmap[j] < water_level - 16)  // Use base terrain heightmap
 				continue;
 
 			float uwatern = noise_ridge_uwater->result[j] * 2;
@@ -805,6 +767,36 @@ void MapgenV7::generateCaves(s16 max_stone_y)
 ///////////////////////////////////////////////////////////////
 
 
+#if 0
+int MapgenV7::generateMountainTerrain(s16 ymax)
+{
+	MapNode n_stone(c_stone);
+	u32 j = 0;
+
+	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++) {
+			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)
+					&& (c == CONTENT_AIR || c == c_water_source)) {
+				vm->m_data[vi] = n_stone;
+				if (y > ymax)
+					ymax = y;
+			}
+
+			vi++;
+			j++;
+		}
+	}
+
+	return ymax;
+}
+#endif
+
+
 #if 0
 void MapgenV7::carveRivers() {
 	MapNode n_air(CONTENT_AIR), n_water_source(c_water_source);

src/mapgen_v7.h

@@ -59,6 +59,7 @@ class MapgenV7 : public Mapgen {
 	BiomeManager *bmgr;
 
 	int ystride;
+	int zstride_1u1d;
 	int zstride_1d;
 	u32 spflags;
 
@@ -113,16 +114,12 @@ class MapgenV7 : public Mapgen {
 
 	void calculateNoise();
 
-	virtual int generateTerrain();
-	void generateBaseTerrain(s16 *stone_surface_min_y, s16 *stone_surface_max_y);
-	int generateMountainTerrain(s16 ymax);
+	int generateTerrain();
 	void generateRidgeTerrain();
 
 	MgStoneType generateBiomes(float *heat_map, float *humidity_map);
 	void dustTopNodes();
 
-	//void addTopNodes();
-
 	void generateCaves(s16 max_stone_y);
 };