From c8be58a65ce5f06bc23353b41caf9495e3b9d484 Mon Sep 17 00:00:00 2001
From: Perttu Ahola <celeron55@gmail.com>
Date: Mon, 28 Feb 2011 02:01:40 +0200
Subject: A third try on terrain generation. No trees yet.

---
 src/noise.cpp | 35 ++++++++++++++++++++++++++++++++---
 1 file changed, 32 insertions(+), 3 deletions(-)

(limited to 'src/noise.cpp')

diff --git a/src/noise.cpp b/src/noise.cpp
index 63682e1e4..bc5148545 100644
--- a/src/noise.cpp
+++ b/src/noise.cpp
@@ -92,8 +92,7 @@ double noise3d(int x, int y, int z, int seed)
 	return 1.0 - (double)n/1073741824;
 }
 
-#if 0
-// This is too slow
+#if 1
 double noise2d_gradient(double x, double y, int seed)
 {
 	// Calculate the integer coordinates
@@ -118,7 +117,7 @@ double noise2d_gradient(double x, double y, int seed)
 }
 #endif
 
-#if 1
+#if 0
 double noise2d_gradient(double x, double y, int seed)
 {
 	// Calculate the integer coordinates
@@ -175,6 +174,21 @@ double noise2d_perlin(double x, double y, int seed,
 	return a;
 }
 
+double noise2d_perlin_abs(double x, double y, int seed,
+		int octaves, double persistence)
+{
+	double a = 0;
+	double f = 1.0;
+	double g = 1.0;
+	for(int i=0; i<octaves; i++)
+	{
+		a += g * fabs(noise2d_gradient(x*f, y*f, seed+i));
+		f *= 2.0;
+		g *= persistence;
+	}
+	return a;
+}
+
 double noise3d_perlin(double x, double y, double z, int seed,
 		int octaves, double persistence)
 {
@@ -190,3 +204,18 @@ double noise3d_perlin(double x, double y, double z, int seed,
 	return a;
 }
 
+double noise3d_perlin_abs(double x, double y, double z, int seed,
+		int octaves, double persistence)
+{
+	double a = 0;
+	double f = 1.0;
+	double g = 1.0;
+	for(int i=0; i<octaves; i++)
+	{
+		a += g * fabs(noise3d_gradient(x*f, y*f, z*f, seed+i));
+		f *= 2.0;
+		g *= persistence;
+	}
+	return a;
+}
+
-- 
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