From c367f7301a4bd2f69a84b53392439482abd6dc5a Mon Sep 17 00:00:00 2001
From: paramat <mat.gregory@virginmedia.com>
Date: Sun, 11 Jan 2015 09:21:55 +0000
Subject: Mapgen V5: Move cave generation from base terrain loop to optional
 function

This fixes biome surface in tunnels
---
 src/mapgen_v5.cpp | 37 +++++++++++++++++++++++++++++++------
 src/mapgen_v5.h   |  1 +
 2 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/src/mapgen_v5.cpp b/src/mapgen_v5.cpp
index e220455bf..23bc85450 100644
--- a/src/mapgen_v5.cpp
+++ b/src/mapgen_v5.cpp
@@ -268,6 +268,10 @@ void MapgenV5::makeChunk(BlockMakeData *data)
 	// Actually place the biome-specific nodes
 	generateBiomes();
 
+	// Generate caves
+	if ((flags & MG_CAVES) && (stone_surface_max_y >= node_min.Y))
+		generateCaves();
+
 	// Generate dungeons and desert temples
 	if ((flags & MG_DUNGEONS) && (stone_surface_max_y >= node_min.Y)) {
 		DungeonGen dgen(this, NULL);
@@ -309,8 +313,11 @@ void MapgenV5::calculateNoise()
 	noise_factor->perlinMap2D(x, z);
 	noise_height->perlinMap2D(x, z);
 
-	noise_cave1->perlinMap3D(x, y, z);
-	noise_cave2->perlinMap3D(x, y, z);
+	if (flags & MG_CAVES) {
+		noise_cave1->perlinMap3D(x, y, z);
+		noise_cave2->perlinMap3D(x, y, z);
+	}
+
 	noise_ground->perlinMap3D(x, y, z);
 
 	if (spflags & MGV5_BLOBS) {
@@ -363,16 +370,12 @@ int MapgenV5::generateBaseTerrain()
 				else if(f >= 1.0)
 					f *= 1.6;
 				float h = water_level + noise_height->result[index2d];
-				float d1 = contour(noise_cave1->result[index]);
-				float d2 = contour(noise_cave2->result[index]);
 
 				if(noise_ground->result[index] * f < y - h) {
 					if(y <= water_level)
 						vm->m_data[i] = MapNode(c_water_source);
 					else
 						vm->m_data[i] = MapNode(CONTENT_AIR);
-				} else if(d1*d2 > 0.2) {
-					vm->m_data[i] = MapNode(CONTENT_AIR);
 				} else {
 					vm->m_data[i] = MapNode(c_stone);
 					if (y > stone_surface_max_y)
@@ -508,6 +511,28 @@ void MapgenV5::generateBiomes()
 }
 
 
+void MapgenV5::generateCaves()
+{
+	u32 index = 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 i = vm->m_area.index(node_min.X, y, z);
+			for(s16 x=node_min.X; x<=node_max.X; x++, i++, index++) {
+				content_t c = vm->m_data[i].getContent();
+				if(c == CONTENT_AIR || c == c_water_source)
+					continue;
+
+				float d1 = contour(noise_cave1->result[index]);
+				float d2 = contour(noise_cave2->result[index]);
+				if(d1*d2 > 0.2)
+					vm->m_data[i] = MapNode(CONTENT_AIR);
+			}
+		}
+	}
+}
+
+
 void MapgenV5::dustTopNodes()
 {
 	v3s16 em = vm->m_area.getExtent();
diff --git a/src/mapgen_v5.h b/src/mapgen_v5.h
index 18f0ffa03..bf8efad14 100644
--- a/src/mapgen_v5.h
+++ b/src/mapgen_v5.h
@@ -97,6 +97,7 @@ public:
 	int generateBaseTerrain();
 	void generateBlobs();
 	void generateBiomes();
+	void generateCaves();
 	void dustTopNodes();
 };
 
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