Cavegen: Rename CaveV6 to CavesV6

- Add comment explaining why it exists
- Remove unused 'flooded' variable
- Rename shadowed variable
- Fix some code style

3 files changed, 41 insertions, 29 deletions

diff --git a/src/cavegen.cpp b/src/cavegen.cpp
index 59274101e..e6e21be40 100644
--- a/src/cavegen.cpp
+++ b/src/cavegen.cpp
@@ -277,10 +277,12 @@ void CavesRandomWalk::carveRoute(v3f vec, float f, bool randomize_xz)
 }
 
 
-///////////////////////////////////////// Caves V6
+////
+//// CavesV6
+////
 
-
-CaveV6::CaveV6(MapgenV6 *mg, PseudoRandom *ps, PseudoRandom *ps2, bool is_large_cave)
+CavesV6::CavesV6(MapgenV6 *mg, PseudoRandom *ps, PseudoRandom *ps2,
+	bool is_large_cave)
 {
 	this->mg             = mg;
 	this->vm             = mg->vm;
@@ -295,23 +297,22 @@ CaveV6::CaveV6(MapgenV6 *mg, PseudoRandom *ps, PseudoRandom *ps2, bool is_large_
 	min_tunnel_diameter = 2;
 	max_tunnel_diameter = ps->range(2, 6);
 	dswitchint          = ps->range(1, 14);
-	flooded             = true;
 
 	if (large_cave) {
-		part_max_length_rs  = ps->range(2,4);
-		tunnel_routepoints  = ps->range(5, ps->range(15,30));
+		part_max_length_rs  = ps->range(2, 4);
+		tunnel_routepoints  = ps->range(5, ps->range(15, 30));
 		min_tunnel_diameter = 5;
-		max_tunnel_diameter = ps->range(7, ps->range(8,24));
+		max_tunnel_diameter = ps->range(7, ps->range(8, 24));
 	} else {
-		part_max_length_rs = ps->range(2,9);
-		tunnel_routepoints = ps->range(10, ps->range(15,30));
+		part_max_length_rs = ps->range(2, 9);
+		tunnel_routepoints = ps->range(10, ps->range(15, 30));
 	}
 
-	large_cave_is_flat = (ps->range(0,1) == 0);
+	large_cave_is_flat = (ps->range(0, 1) == 0);
 }
 
 
-void CaveV6::makeCave(v3s16 nmin, v3s16 nmax, int max_stone_height)
+void CavesV6::makeCave(v3s16 nmin, v3s16 nmax, int max_stone_height)
 {
 	node_min = nmin;
 	node_max = nmax;
@@ -328,8 +329,8 @@ void CaveV6::makeCave(v3s16 nmin, v3s16 nmax, int max_stone_height)
 	const s16 max_spread_amount = MAP_BLOCKSIZE;
 	s16 insure = 10;
 	s16 more = MYMAX(max_spread_amount - max_tunnel_diameter / 2 - insure, 1);
-	ar += v3s16(1,0,1) * more * 2;
-	of -= v3s16(1,0,1) * more;
+	ar += v3s16(1, 0, 1) * more * 2;
+	of -= v3s16(1, 0, 1) * more;
 
 	route_y_min = 0;
 	// Allow half a diameter + 7 over stone surface
@@ -339,20 +340,20 @@ void CaveV6::makeCave(v3s16 nmin, v3s16 nmax, int max_stone_height)
 	route_y_max = rangelim(route_y_max, 0, ar.Y - 1);
 
 	if (large_cave) {
-		s16 min = 0;
+		s16 minpos = 0;
 		if (node_min.Y < water_level && node_max.Y > water_level) {
-			min = water_level - max_tunnel_diameter/3 - of.Y;
-			route_y_max = water_level + max_tunnel_diameter/3 - of.Y;
+			minpos = water_level - max_tunnel_diameter / 3 - of.Y;
+			route_y_max = water_level + max_tunnel_diameter / 3 - of.Y;
 		}
-		route_y_min = ps->range(min, min + max_tunnel_diameter);
+		route_y_min = ps->range(minpos, minpos + max_tunnel_diameter);
 		route_y_min = rangelim(route_y_min, 0, route_y_max);
 	}
 
 	s16 route_start_y_min = route_y_min;
 	s16 route_start_y_max = route_y_max;
 
-	route_start_y_min = rangelim(route_start_y_min, 0, ar.Y-1);
-	route_start_y_max = rangelim(route_start_y_max, route_start_y_min, ar.Y-1);
+	route_start_y_min = rangelim(route_start_y_min, 0, ar.Y - 1);
+	route_start_y_max = rangelim(route_start_y_max, route_start_y_min, ar.Y - 1);
 
 	// Randomize starting position
 	orp = v3f(
@@ -379,7 +380,7 @@ void CaveV6::makeCave(v3s16 nmin, v3s16 nmax, int max_stone_height)
 }
 
 
-void CaveV6::makeTunnel(bool dirswitch)
+void CavesV6::makeTunnel(bool dirswitch)
 {
 	if (dirswitch && !large_cave) {
 		main_direction = v3f(
@@ -496,7 +497,8 @@ void CaveV6::makeTunnel(bool dirswitch)
 }
 
 
-void CaveV6::carveRoute(v3f vec, float f, bool randomize_xz, bool tunnel_above_ground)
+void CavesV6::carveRoute(v3f vec, float f, bool randomize_xz,
+	bool tunnel_above_ground)
 {
 	MapNode airnode(CONTENT_AIR);
 	MapNode waternode(c_water_source);
@@ -547,11 +549,10 @@ void CaveV6::carveRoute(v3f vec, float f, bool randomize_xz, bool tunnel_above_g
 					int full_ymin = node_min.Y - MAP_BLOCKSIZE;
 					int full_ymax = node_max.Y + MAP_BLOCKSIZE;
 
-					if (flooded && full_ymin < water_level &&
-							full_ymax > water_level) {
+					if (full_ymin < water_level && full_ymax > water_level) {
 						vm->m_data[i] = (p.Y <= water_level) ?
 							waternode : airnode;
-					} else if (flooded && full_ymax < water_level) {
+					} else if (full_ymax < water_level) {
 						vm->m_data[i] = (p.Y < startp.Y - 2) ?
 							lavanode : airnode;
 					} else {
diff --git a/src/cavegen.h b/src/cavegen.h
index c907fe294..b50455c1c 100644
--- a/src/cavegen.h
+++ b/src/cavegen.h
@@ -72,7 +72,20 @@ public:
 	void carveRoute(v3f vec, float f, bool randomize_xz);
 };
 
-class CaveV6 {
+/*
+	CavesV6 is the original version of caves used with Mapgen V6.
+
+	Though it uses the same fundamental algorithm as CavesRandomWalk, it is made
+	separate to preserve the exact sequence of PseudoRandom calls - any change
+	to this ordering results in the output being radically different.
+	Because caves in Mapgen V6 are responsible for a large portion of the basic
+	terrain shape, modifying this will break our contract of reverse
+	compatibility for a 'stable' mapgen such as V6.
+
+	tl;dr,
+	*** DO NOT TOUCH THIS CLASS UNLESS YOU KNOW WHAT YOU ARE DOING ***
+*/
+class CavesV6 {
 public:
 	MapgenV6 *mg;
 	MMVManip *vm;
@@ -86,7 +99,6 @@ public:
 
 	bool large_cave;
 	bool large_cave_is_flat;
-	bool flooded;
 
 	s16 max_stone_y;
 	v3s16 node_min;
@@ -109,8 +121,7 @@ public:
 
 	int water_level;
 
-	CaveV6() {}
-	CaveV6(MapgenV6 *mg, PseudoRandom *ps, PseudoRandom *ps2, bool large_cave);
+	CavesV6(MapgenV6 *mg, PseudoRandom *ps, PseudoRandom *ps2, bool large_cave);
 	void makeCave(v3s16 nmin, v3s16 nmax, int max_stone_height);
 	void makeTunnel(bool dirswitch);
 	void carveRoute(v3f vec, float f, bool randomize_xz, bool tunnel_above_ground);
diff --git a/src/mapgen_v6.cpp b/src/mapgen_v6.cpp
index c389b2ed4..d143f12e9 100644
--- a/src/mapgen_v6.cpp
+++ b/src/mapgen_v6.cpp
@@ -1067,7 +1067,7 @@ void MapgenV6::generateCaves(int max_stone_y)
 
 	for (u32 i = 0; i < caves_count + bruises_count; i++) {
 		bool large_cave = (i >= caves_count);
-		CaveV6 cave(this, &ps, &ps2, large_cave);
+		CavesV6 cave(this, &ps, &ps2, large_cave);
 
 		cave.makeCave(node_min, node_max, max_stone_y);
 	}