1 files changed, 132 insertions, 0 deletions

diff --git a/OpenSim/Region/Framework/Scenes/TerrainUtil.cs b/OpenSim/Region/Framework/Scenes/TerrainUtil.cs
new file mode 100644
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+++ b/OpenSim/Region/Framework/Scenes/TerrainUtil.cs
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+/*
+ * Copyright (c) Contributors, http://opensimulator.org/
+ * See CONTRIBUTORS.TXT for a full list of copyright holders.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *     * Redistributions of source code must retain the above copyright
+ *       notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above copyright
+ *       notice, this list of conditions and the following disclaimer in the
+ *       documentation and/or other materials provided with the distribution.
+ *     * Neither the name of the OpenSim Project nor the
+ *       names of its contributors may be used to endorse or promote products
+ *       derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+using System;
+using OpenSim.Region.Framework.Interfaces;
+
+namespace OpenSim.Region.Framework.Scenes
+{
+    public static class TerrainUtil
+    {
+        public static double MetersToSphericalStrength(double size)
+        {
+            //return Math.Pow(2, size);
+            return (size + 1) * 1.35; // MCP: a more useful brush size range
+        }
+
+        public static double SphericalFactor(double x, double y, double rx, double ry, double size)
+        {
+            return size * size - ((x - rx) * (x - rx) + (y - ry) * (y - ry));
+        }
+
+        public static double GetBilinearInterpolate(double x, double y, ITerrainChannel map)
+        {
+            int w = map.Width;
+            int h = map.Height;
+
+            if (x > w - 2.0)
+                x = w - 2.0;
+            if (y > h - 2.0)
+                y = h - 2.0;
+            if (x < 0.0)
+                x = 0.0;
+            if (y < 0.0)
+                y = 0.0;
+
+            const int stepSize = 1;
+            double h00 = map[(int) x, (int) y];
+            double h10 = map[(int) x + stepSize, (int) y];
+            double h01 = map[(int) x, (int) y + stepSize];
+            double h11 = map[(int) x + stepSize, (int) y + stepSize];
+            double h1 = h00;
+            double h2 = h10;
+            double h3 = h01;
+            double h4 = h11;
+            double a00 = h1;
+            double a10 = h2 - h1;
+            double a01 = h3 - h1;
+            double a11 = h1 - h2 - h3 + h4;
+            double partialx = x - (int) x;
+            double partialz = y - (int) y;
+            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);
+        }
+
+        public 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 total = 0.0;
+
+            for (int i = 0; i < octaves; i++)
+            {
+                double frequency = Math.Pow(2, i);
+                double amplitude = Math.Pow(persistence, i);
+
+                total += InterpolatedNoise(x * frequency, y * frequency) * amplitude;
+            }
+            return total;
+        }
+    }
+}