From 7ef94f4e55a0b798eecbcc7166a80b8364b21ea4 Mon Sep 17 00:00:00 2001
From: Daniel Karbach <daniel.karbach@localhorst.tv>
Date: Mon, 23 Mar 2015 23:28:41 +0100
Subject: [PATCH] use 3 octaves for solid generation noise

also, that other perlin implementation sucked noodles
---
 TODO              |  2 --
 src/generator.cpp |  6 +++---
 src/generator.hpp |  2 +-
 src/noise.cpp     |  5 ++---
 src/noise.hpp     | 24 ++++++++++++++++++++++++
 5 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/TODO b/TODO
index 244e938..363c635 100644
--- a/TODO
+++ b/TODO
@@ -79,5 +79,3 @@ entity/world collision
 better noise
 
 	current simplex noise implementation repeats itself pretty quickly
-	also there seems to be a (imo) better implementation here:
-	http://flafla2.github.io/2014/08/09/perlinnoise.html
diff --git a/src/generator.cpp b/src/generator.cpp
index 43d932c..dc83b89 100644
--- a/src/generator.cpp
+++ b/src/generator.cpp
@@ -8,7 +8,7 @@ namespace blank {
 Generator::Generator(const Config &config)
 : solidNoise(config.solid_seed)
 , typeNoise(config.type_seed)
-, stretch(config.stretch)
+, stretch(1.0f/config.stretch)
 , solid_threshold(config.solid_threshold)
 , space(0)
 , light(0)
@@ -25,8 +25,8 @@ void Generator::operator ()(Chunk &chunk) const {
 		for (int y = 0; y < Chunk::Height(); ++y) {
 			for (int x = 0; x < Chunk::Width(); ++x) {
 				Block::Pos block_pos(x, y, z);
-				glm::vec3 gen_pos = (coords + block_pos) / stretch;
-				float val = solidNoise(gen_pos);
+				glm::vec3 gen_pos = (coords + block_pos) * stretch;
+				float val = OctaveNoise(solidNoise, coords + block_pos, 3, 0.5f, stretch, 2.0f);
 				if (val > solid_threshold) {
 					int type_val = int((typeNoise(gen_pos) + 1.0f) * solids.size()) % solids.size();
 					chunk.SetBlock(block_pos, Block(solids[type_val]));
diff --git a/src/generator.hpp b/src/generator.hpp
index 3d7ceaf..70c38f5 100644
--- a/src/generator.hpp
+++ b/src/generator.hpp
@@ -17,7 +17,7 @@ public:
 		unsigned int solid_seed = 0;
 		unsigned int type_seed = 0;
 		float stretch = 64.0f;
-		float solid_threshold = 0.8f;
+		float solid_threshold = 0.5f;
 	};
 
 	explicit Generator(const Config &);
diff --git a/src/noise.cpp b/src/noise.cpp
index 6d59224..8b71614 100644
--- a/src/noise.cpp
+++ b/src/noise.cpp
@@ -45,10 +45,9 @@ SimplexNoise::SimplexNoise(unsigned int seed)
 	{  0.0f,  1.0f, -1.0f },
 	{  0.0f, -1.0f, -1.0f },
 }) {
-	unsigned int val = seed;
+	GaloisLFSR random(seed ^ 0x0123456789ACBDEF);
 	for (size_t i = 0; i < 256; ++i) {
-		val = 2346765 * val + 6446345;
-		perm[i] = val % 256;
+		random(perm[i]);
 		perm[i + 256] = perm[i];
 	}
 }
diff --git a/src/noise.hpp b/src/noise.hpp
index 166a60a..26e3766 100644
--- a/src/noise.hpp
+++ b/src/noise.hpp
@@ -35,6 +35,7 @@ private:
 
 };
 
+
 /// (3D only) adaptation of Stefan Gustavson's SimplexNoise java class
 class SimplexNoise {
 
@@ -68,6 +69,29 @@ private:
 
 };
 
+
+template<class Noise>
+float OctaveNoise(
+	const Noise &noise,
+	const glm::vec3 &in,
+	int num,
+	float persistence,
+	float frequency = 1.0f,
+	float amplitude = 1.0f,
+	float growth = 2.0f
+) {
+	float total = 0.0f;
+	float max = 0.0f;
+	for (int i = 0; i < num; ++i) {
+		total += noise(in * frequency) * amplitude;
+		max += amplitude;
+		amplitude *= persistence;
+		frequency *= growth;
+	}
+
+	return total / max;
+}
+
 }
 
 #endif
-- 
2.39.2