123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125 |
- using System;
- using OpenSim.Region.Framework.Interfaces;
- namespace OpenSim.Region.Framework.Scenes
- {
- public static class TerrainUtil
- {
- public static float SphericalFactor(float dx, float dy, float size)
- {
- float a = ((dx * dx) + (dy * dy))/ (size * size);
- if( a >= 1.0f)
- return 0;
- return 1.0f - a;
- }
- 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 a00 = h00;
- double a10 = h10 - h00;
- double a01 = h01 - h00;
- double a11 = h11 - h10 - h01 + h00;
- double partialx = x - (int) x;
- double partialy = y - (int) y;
- double hi = a00 + (a10 * partialx) + (a01 * partialy) + (a11 * partialx * partialy);
- 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;
- }
- }
- }
|