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126 lines
4.9 KiB
C#
126 lines
4.9 KiB
C#
/*
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* Copyright (c) Contributors, http://opensimulator.org/
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* See CONTRIBUTORS.TXT for a full list of copyright holders.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of the OpenSimulator Project nor the
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* names of its contributors may be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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using System;
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using OpenSim.Region.Framework.Interfaces;
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namespace OpenSim.Region.Framework.Scenes
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{
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public static class TerrainUtil
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{
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public static float SphericalFactor(float dx, float dy, float size)
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{
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float a = ((dx * dx) + (dy * dy))/ (size * size);
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if( a >= 1.0f)
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return 0;
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return 1.0f - a;
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}
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public static double GetBilinearInterpolate(double x, double y, ITerrainChannel map)
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{
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int w = map.Width;
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int h = map.Height;
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if (x > w - 2.0)
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x = w - 2.0;
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if (y > h - 2.0)
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y = h - 2.0;
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if (x < 0.0)
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x = 0.0;
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if (y < 0.0)
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y = 0.0;
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const int stepSize = 1;
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double h00 = map[(int) x, (int) y];
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double h10 = map[(int) x + stepSize, (int) y];
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double h01 = map[(int) x, (int) y + stepSize];
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double h11 = map[(int) x + stepSize, (int) y + stepSize];
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double a00 = h00;
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double a10 = h10 - h00;
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double a01 = h01 - h00;
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double a11 = h11 - h10 - h01 + h00;
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double partialx = x - (int) x;
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double partialy = y - (int) y;
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double hi = a00 + (a10 * partialx) + (a01 * partialy) + (a11 * partialx * partialy);
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return hi;
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}
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private static double Noise(double x, double y)
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{
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int n = (int) x + (int) (y * 749);
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n = (n << 13) ^ n;
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return (1.0 - ((n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0);
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}
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private static double SmoothedNoise1(double x, double y)
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{
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double corners = (Noise(x - 1, y - 1) + Noise(x + 1, y - 1) + Noise(x - 1, y + 1) + Noise(x + 1, y + 1)) / 16;
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double sides = (Noise(x - 1, y) + Noise(x + 1, y) + Noise(x, y - 1) + Noise(x, y + 1)) / 8;
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double center = Noise(x, y) / 4;
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return corners + sides + center;
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}
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private static double Interpolate(double x, double y, double z)
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{
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return (x * (1.0 - z)) + (y * z);
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}
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public static double InterpolatedNoise(double x, double y)
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{
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int integer_X = (int) (x);
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double fractional_X = x - integer_X;
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int integer_Y = (int) y;
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double fractional_Y = y - integer_Y;
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double v1 = SmoothedNoise1(integer_X, integer_Y);
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double v2 = SmoothedNoise1(integer_X + 1, integer_Y);
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double v3 = SmoothedNoise1(integer_X, integer_Y + 1);
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double v4 = SmoothedNoise1(integer_X + 1, integer_Y + 1);
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double i1 = Interpolate(v1, v2, fractional_X);
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double i2 = Interpolate(v3, v4, fractional_X);
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return Interpolate(i1, i2, fractional_Y);
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}
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public static double PerlinNoise2D(double x, double y, int octaves, double persistence)
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{
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double total = 0.0;
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for (int i = 0; i < octaves; i++)
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{
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double frequency = Math.Pow(2, i);
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double amplitude = Math.Pow(persistence, i);
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total += InterpolatedNoise(x * frequency, y * frequency) * amplitude;
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}
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return total;
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}
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}
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}
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