Mgv5/v7/flat/fractal: Move tunnel noise calculation into generateCaves

Tunnel 3D noises are only calculated when solid terrain is present
in mapchunk, avoiding large amounts of unnecessary calculations
Change 'int' to 's16' in calculateNoise
Change 'i' to 'vi' for voxelmanip indexes for consistency
Keep 'u32 index3d' local to a smaller part of tunnel code
Mgv7: Don't call CaveV7 if no solid terrain in mapchunk
Give 'open' bool a more descriptive name

1 files changed, 53 insertions, 50 deletions

diff --git a/src/mapgen_v7.cpp b/src/mapgen_v7.cpp
index 1e4815486..aec00b938 100644
--- a/src/mapgen_v7.cpp
+++ b/src/mapgen_v7.cpp
@@ -345,9 +345,9 @@ void MapgenV7::makeChunk(BlockMakeData *data)
 void MapgenV7::calculateNoise()
 {
 	//TimeTaker t("calculateNoise", NULL, PRECISION_MICRO);
-	int x = node_min.X;
-	int y = node_min.Y - 1;
-	int z = node_min.Z;
+	s16 x = node_min.X;
+	s16 y = node_min.Y - 1;
+	s16 z = node_min.Z;
 
 	noise_terrain_persist->perlinMap2D(x, z);
 	float *persistmap = noise_terrain_persist->result;
@@ -356,17 +356,16 @@ void MapgenV7::calculateNoise()
 	noise_terrain_alt->perlinMap2D(x, z, persistmap);
 	noise_height_select->perlinMap2D(x, z);
 
-	if (flags & MG_CAVES) {
-		noise_cave1->perlinMap3D(x, y, z);
-		noise_cave2->perlinMap3D(x, y, z);
-	}
-
 	if ((spflags & MGV7_RIDGES) && node_max.Y >= water_level) {
 		noise_ridge->perlinMap3D(x, y, z);
 		noise_ridge_uwater->perlinMap2D(x, z);
 	}
 
+	// 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);
@@ -527,17 +526,17 @@ void MapgenV7::generateBaseTerrain(s16 *stone_surface_min_y, s16 *stone_surface_
 		if (surface_y > surface_max_y)
 			surface_max_y = surface_y;
 
-		u32 i = vm->m_area.index(x, node_min.Y - 1, z);
+		u32 vi = vm->m_area.index(x, node_min.Y - 1, z);
 		for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
-			if (vm->m_data[i].getContent() == CONTENT_IGNORE) {
+			if (vm->m_data[vi].getContent() == CONTENT_IGNORE) {
 				if (y <= surface_y)
-					vm->m_data[i] = n_stone;
+					vm->m_data[vi] = n_stone;
 				else if (y <= water_level)
-					vm->m_data[i] = n_water;
+					vm->m_data[vi] = n_water;
 				else
-					vm->m_data[i] = n_air;
+					vm->m_data[vi] = n_air;
 			}
-			vm->m_area.add_y(em, i, 1);
+			vm->m_area.add_y(em, vi, 1);
 		}
 	}
 
@@ -585,7 +584,7 @@ void MapgenV7::generateRidgeTerrain()
 	MapNode n_water(c_water_source);
 	MapNode n_air(CONTENT_AIR);
 	u32 index = 0;
-	float width = 0.2; // TODO: figure out acceptable perlin noise values
+	float width = 0.2;
 
 	for (s16 z = node_min.Z; z <= node_max.Z; z++)
 	for (s16 y = node_min.Y - 1; y <= node_max.Y + 1; y++) {
@@ -862,41 +861,45 @@ void MapgenV7::addTopNodes()
 
 void MapgenV7::generateCaves(s16 max_stone_y)
 {
-	if (max_stone_y >= node_min.Y) {
-		v3s16 em = vm->m_area.getExtent();
-		u32 index2d = 0;
-		u32 index3d;
-
-		for (s16 z = node_min.Z; z <= node_max.Z; z++)
-		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;
-				}
+	if (max_stone_y < node_min.Y)
+		return;
+
+	noise_cave1->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
+	noise_cave2->perlinMap3D(node_min.X, node_min.Y - 1, node_min.Z);
+
+	v3s16 em = vm->m_area.getExtent();
+	u32 index2d = 0;
+
+	for (s16 z = node_min.Z; z <= node_max.Z; z++)
+	for (s16 x = node_min.X; x <= node_max.X; x++, index2d++) {
+		bool column_is_open = false;  // Is column open to overground
+		u32 vi = vm->m_area.index(x, node_max.Y + 1, z);
+		u32 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) {
+				column_is_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 (column_is_open &&
+					(c == biome->c_filler || c == biome->c_stone)) {
+				// Tunnel entrance floor
+				vm->m_data[vi] = MapNode(biome->c_top);
+				column_is_open = false;
+			} else {
+				column_is_open = false;
 			}
 		}
 	}