From 1cd8351054c6f0b120e603e0e25b85da385f185a Mon Sep 17 00:00:00 2001
From: kwolekr <mirrorisim@gmail.com>
Date: Mon, 7 Jan 2013 16:42:00 -0500
Subject: [PATCH] Fix MapgenV6::getGroundLevelAtPoint()

---
 src/mapgen.h      |  2 +-
 src/mapgen_v6.cpp | 35 +++++++++++++++++++++++++++++++++--
 src/noise.h       | 24 ++++++++++++++++++++++--
 3 files changed, 56 insertions(+), 5 deletions(-)

diff --git a/src/mapgen.h b/src/mapgen.h
index ba1ea86c3..68f6f61e2 100644
--- a/src/mapgen.h
+++ b/src/mapgen.h
@@ -202,7 +202,7 @@ public:
 	void makeChunk(BlockMakeData *data);
 	int getGroundLevelAtPoint(v2s16 p);
 
-
+	double baseRockLevelFromNoise(v2s16 p);
 	static s16 find_ground_level(VoxelManipulator &vmanip, v2s16 p2d, INodeDefManager *ndef);
 	static s16 find_stone_level(VoxelManipulator &vmanip, v2s16 p2d, INodeDefManager *ndef);
 	void make_tree(ManualMapVoxelManipulator &vmanip, v3s16 p0, bool is_apple_tree, INodeDefManager *ndef);
diff --git a/src/mapgen_v6.cpp b/src/mapgen_v6.cpp
index fc6ef89e8..a86edcca9 100644
--- a/src/mapgen_v6.cpp
+++ b/src/mapgen_v6.cpp
@@ -311,9 +311,40 @@ double MapgenV6::base_rock_level_2d(u64 seed, v2s16 p)
 	return h;
 }
 
+double MapgenV6::baseRockLevelFromNoise(v2s16 p) {
+	double base = water_level + 
+		NoisePerlin2DPosOffset(noise_terrain_base->np, p.X, 0.5, p.Y, 0.5, seed);
+	double higher = water_level +
+		NoisePerlin2DPosOffset(noise_terrain_higher->np, p.X, 0.5, p.Y, 0.5, seed);
+
+	if (higher < base)
+		higher = base;
+
+	double b = NoisePerlin2DPosOffset(noise_steepness->np, p.X, 0.5, p.Y, 0.5, seed);
+	b = rangelim(b, 0.0, 1000.0);
+	b = b*b*b*b*b*b*b;
+	b *= 5;
+	b = rangelim(b, 0.5, 1000.0);
+
+	if(b > 1.5 && b < 100.0){
+		if(b < 10.0)
+			b = 1.5;
+		else
+			b = 100.0;
+	}
+	
+	double a_off = -0.20;
+	double a = 0.5 + b * (a_off + NoisePerlin2DNoTxfmPosOffset(
+			noise_height_select->np, p.X, 0.5, p.Y, 0.5, seed));
+	a = rangelim(a, 0.0, 1.0);
+
+	return base * (1.0 - a) + higher * a;
+}
+
+
 s16 MapgenV6::find_ground_level_from_noise(u64 seed, v2s16 p2d, s16 precision)
 {
-	return base_rock_level_2d(seed, p2d) + AVERAGE_MUD_AMOUNT;
+	return baseRockLevelFromNoise(p2d) + AVERAGE_MUD_AMOUNT;
 }
 
 double MapgenV6::get_mud_add_amount(u64 seed, v2s16 p)
@@ -363,7 +394,7 @@ u32 MapgenV6::get_blockseed(u64 seed, v3s16 p)
 
 
 int MapgenV6::getGroundLevelAtPoint(v2s16 p) {
-	return base_rock_level_2d(seed, p) + AVERAGE_MUD_AMOUNT;
+	return baseRockLevelFromNoise(p) + AVERAGE_MUD_AMOUNT;
 }
 
 
diff --git a/src/noise.h b/src/noise.h
index 9fb6d48a1..e725b4e47 100644
--- a/src/noise.h
+++ b/src/noise.h
@@ -132,8 +132,28 @@ inline float easeCurve(float t) {
 	return t * t * t * (t * (6.f * t - 15.f) + 10.f);
 }
 
-#define NoisePerlin2D(np, x, y, s) ((np)->offset + (np)->scale * \
-		noise2d_perlin((float)(x) / (np)->spread.X, (float)(y) / (np)->spread.Y, \
+#define NoisePerlin2D(np, x, y, s) \
+		((np)->offset + (np)->scale * noise2d_perlin( \
+		(float)(x) / (np)->spread.X, \
+		(float)(y) / (np)->spread.Y, \
+		(s) + (np)->seed, (np)->octaves, (np)->persist))
+
+#define NoisePerlin2DNoTxfm(np, x, y, s) \
+		(noise2d_perlin( \
+		(float)(x) / (np)->spread.X, \
+		(float)(y) / (np)->spread.Y, \
+		(s) + (np)->seed, (np)->octaves, (np)->persist))
+
+#define NoisePerlin2DPosOffset(np, x, xoff, y, yoff, s) \
+		((np)->offset + (np)->scale * noise2d_perlin( \
+		(float)(xoff) + (float)(x) / (np)->spread.X, \
+		(float)(yoff) + (float)(y) / (np)->spread.Y, \
+		(s) + (np)->seed, (np)->octaves, (np)->persist))
+
+#define NoisePerlin2DNoTxfmPosOffset(np, x, xoff, y, yoff, s) \
+		(noise2d_perlin( \
+		(float)(xoff) + (float)(x) / (np)->spread.X, \
+		(float)(yoff) + (float)(y) / (np)->spread.Y, \
 		(s) + (np)->seed, (np)->octaves, (np)->persist))
 
 #define NoisePerlin3D(np, x, y, z, s) ((np)->offset + (np)->scale * \