1 files changed, 55 insertions, 0 deletions

diff --git a/OpenSim/Region/Environment/Modules/Terrain/TerrainUtil.cs b/OpenSim/Region/Environment/Modules/Terrain/TerrainUtil.cs
index 23ab321..55265d9 100644
--- a/OpenSim/Region/Environment/Modules/Terrain/TerrainUtil.cs
+++ b/OpenSim/Region/Environment/Modules/Terrain/TerrainUtil.cs
@@ -47,5 +47,60 @@ namespace OpenSim.Region.Environment.Modules.Terrain
             double hi = a00 + (a10 * partialx) + (a01 * partialz) + (a11 * partialx * partialz);
             return hi;
         }
+
+        private static double Noise(double x, double y)
+        {
+            int n = (int)x + (int)(y * 749);
+            n = (n << 13) ^ n;
+            return (1.0 - ((n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0);
+        }
+
+        private static double SmoothedNoise1(double x, double y)
+        {
+            double corners = (Noise(x - 1, y - 1) + Noise(x + 1, y - 1) + Noise(x - 1, y + 1) + Noise(x + 1, y + 1)) / 16;
+            double sides = (Noise(x - 1, y) + Noise(x + 1, y) + Noise(x, y - 1) + Noise(x, y + 1)) / 8;
+            double center = Noise(x, y) / 4;
+            return corners + sides + center;
+        }
+
+        private static double Interpolate(double x, double y, double z)
+        {
+            return (x * (1.0 - z)) + (y * z);
+        }
+
+        private static double InterpolatedNoise(double x, double y)
+        {
+            int integer_X = (int)(x);
+            double fractional_X = x - integer_X;
+
+            int integer_Y = (int)y;
+            double fractional_Y = y - integer_Y;
+
+            double v1 = SmoothedNoise1(integer_X, integer_Y);
+            double v2 = SmoothedNoise1(integer_X + 1, integer_Y);
+            double v3 = SmoothedNoise1(integer_X, integer_Y + 1);
+            double v4 = SmoothedNoise1(integer_X + 1, integer_Y + 1);
+
+            double i1 = Interpolate(v1, v2, fractional_X);
+            double i2 = Interpolate(v3, v4, fractional_X);
+
+            return Interpolate(i1, i2, fractional_Y);
+        }
+
+        public static double PerlinNoise2D(double x, double y, int octaves, double persistence)
+        {
+            double frequency = 0.0;
+            double amplitude = 0.0;
+            double total = 0.0;
+
+            for (int i = 0; i < octaves; i++)
+            {
+                frequency = System.Math.Pow(2, i);
+                amplitude = System.Math.Pow(persistence, i);
+
+                total += InterpolatedNoise(x * frequency, y * frequency) * amplitude;
+            }
+            return total;
+        }
     }
 }