opensim-development – Rev 1
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* 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
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*/
using System;
using OpenMetaverse;
namespace OpenSim.Region.CoreModules.World.Warp3DMap
{
public static class Perlin
{
// We use a hardcoded seed to keep the noise generation consistent between runs
private const int SEED = 42;
private const int SAMPLE_SIZE = 1024;
private const int B = SAMPLE_SIZE;
private const int BM = SAMPLE_SIZE - 1;
private const int N = 0x1000;
private static readonly int[] p = new int[SAMPLE_SIZE + SAMPLE_SIZE + 2];
private static readonly float[,] g3 = new float[SAMPLE_SIZE + SAMPLE_SIZE + 2, 3];
private static readonly float[,] g2 = new float[SAMPLE_SIZE + SAMPLE_SIZE + 2, 2];
private static readonly float[] g1 = new float[SAMPLE_SIZE + SAMPLE_SIZE + 2];
static Perlin()
{
Random rng = new Random(SEED);
int i, j, k;
for (i = 0; i < B; i++)
{
p[i] = i;
g1[i] = (float)((rng.Next() % (B + B)) - B) / B;
for (j = 0; j < 2; j++)
g2[i, j] = (float)((rng.Next() % (B + B)) - B) / B;
normalize2(g2, i);
for (j = 0; j < 3; j++)
g3[i, j] = (float)((rng.Next() % (B + B)) - B) / B;
normalize3(g3, i);
}
while (--i > 0)
{
k = p[i];
p[i] = p[j = rng.Next() % B];
p[j] = k;
}
for (i = 0; i < B + 2; i++)
{
p[B + i] = p[i];
g1[B + i] = g1[i];
for (j = 0; j < 2; j++)
g2[B + i, j] = g2[i, j];
for (j = 0; j < 3; j++)
g3[B + i, j] = g3[i, j];
}
}
public static float noise1(float arg)
{
int bx0, bx1;
float rx0, rx1, sx, t, u, v;
t = arg + N;
bx0 = ((int)t) & BM;
bx1 = (bx0 + 1) & BM;
rx0 = t - (int)t;
rx1 = rx0 - 1f;
sx = s_curve(rx0);
u = rx0 * g1[p[bx0]];
v = rx1 * g1[p[bx1]];
return Utils.Lerp(u, v, sx);
}
public static float noise2(float x, float y)
{
int bx0, bx1, by0, by1, b00, b10, b01, b11;
float rx0, rx1, ry0, ry1, sx, sy, a, b, t, u, v;
int i, j;
t = x + N;
bx0 = ((int)t) & BM;
bx1 = (bx0 + 1) & BM;
rx0 = t - (int)t;
rx1 = rx0 - 1f;
t = y + N;
by0 = ((int)t) & BM;
by1 = (by0 + 1) & BM;
ry0 = t - (int)t;
ry1 = ry0 - 1f;
i = p[bx0];
j = p[bx1];
b00 = p[i + by0];
b10 = p[j + by0];
b01 = p[i + by1];
b11 = p[j + by1];
sx = s_curve(rx0);
sy = s_curve(ry0);
u = rx0 * g2[b00, 0] + ry0 * g2[b00, 1];
v = rx1 * g2[b10, 0] + ry0 * g2[b10, 1];
a = Utils.Lerp(u, v, sx);
u = rx0 * g2[b01, 0] + ry1 * g2[b01, 1];
v = rx1 * g2[b11, 0] + ry1 * g2[b11, 1];
b = Utils.Lerp(u, v, sx);
return Utils.Lerp(a, b, sy);
}
public static float noise3(float x, float y, float z)
{
int bx0, bx1, by0, by1, bz0, bz1, b00, b10, b01, b11;
float rx0, rx1, ry0, ry1, rz0, rz1, sy, sz, a, b, c, d, t, u, v;
int i, j;
t = x + N;
bx0 = ((int)t) & BM;
bx1 = (bx0 + 1) & BM;
rx0 = t - (int)t;
rx1 = rx0 - 1f;
t = y + N;
by0 = ((int)t) & BM;
by1 = (by0 + 1) & BM;
ry0 = t - (int)t;
ry1 = ry0 - 1f;
t = z + N;
bz0 = ((int)t) & BM;
bz1 = (bz0 + 1) & BM;
rz0 = t - (int)t;
rz1 = rz0 - 1f;
i = p[bx0];
j = p[bx1];
b00 = p[i + by0];
b10 = p[j + by0];
b01 = p[i + by1];
b11 = p[j + by1];
t = s_curve(rx0);
sy = s_curve(ry0);
sz = s_curve(rz0);
u = rx0 * g3[b00 + bz0, 0] + ry0 * g3[b00 + bz0, 1] + rz0 * g3[b00 + bz0, 2];
v = rx1 * g3[b10 + bz0, 0] + ry0 * g3[b10 + bz0, 1] + rz0 * g3[b10 + bz0, 2];
a = Utils.Lerp(u, v, t);
u = rx0 * g3[b01 + bz0, 0] + ry1 * g3[b01 + bz0, 1] + rz0 * g3[b01 + bz0, 2];
v = rx1 * g3[b11 + bz0, 0] + ry1 * g3[b11 + bz0, 1] + rz0 * g3[b11 + bz0, 2];
b = Utils.Lerp(u, v, t);
c = Utils.Lerp(a, b, sy);
u = rx0 * g3[b00 + bz1, 0] + ry0 * g3[b00 + bz1, 1] + rz1 * g3[b00 + bz1, 2];
v = rx1 * g3[b10 + bz1, 0] + ry0 * g3[b10 + bz1, 1] + rz1 * g3[b10 + bz1, 2];
a = Utils.Lerp(u, v, t);
u = rx0 * g3[b01 + bz1, 0] + ry1 * g3[b01 + bz1, 1] + rz1 * g3[b01 + bz1, 2];
v = rx1 * g3[b11 + bz1, 0] + ry1 * g3[b11 + bz1, 1] + rz1 * g3[b11 + bz1, 2];
b = Utils.Lerp(u, v, t);
d = Utils.Lerp(a, b, sy);
return Utils.Lerp(c, d, sz);
}
public static float turbulence1(float x, float freq)
{
float t;
float v;
for (t = 0f; freq >= 1f; freq *= 0.5f)
{
v = freq * x;
t += noise1(v) / freq;
}
return t;
}
public static float turbulence2(float x, float y, float freq)
{
float t;
Vector2 vec;
for (t = 0f; freq >= 1f; freq *= 0.5f)
{
vec.X = freq * x;
vec.Y = freq * y;
t += noise2(vec.X, vec.Y) / freq;
}
return t;
}
public static float turbulence3(float x, float y, float z, float freq)
{
float t;
Vector3 vec;
for (t = 0f; freq >= 1f; freq *= 0.5f)
{
vec.X = freq * x;
vec.Y = freq * y;
vec.Z = freq * z;
t += noise3(vec.X, vec.Y, vec.Z) / freq;
}
return t;
}
private static void normalize2(float[,] v, int i)
{
float s;
s = (float)Math.Sqrt(v[i, 0] * v[i, 0] + v[i, 1] * v[i, 1]);
s = 1.0f / s;
v[i, 0] = v[i, 0] * s;
v[i, 1] = v[i, 1] * s;
}
private static void normalize3(float[,] v, int i)
{
float s;
s = (float)Math.Sqrt(v[i, 0] * v[i, 0] + v[i, 1] * v[i, 1] + v[i, 2] * v[i, 2]);
s = 1.0f / s;
v[i, 0] = v[i, 0] * s;
v[i, 1] = v[i, 1] * s;
v[i, 2] = v[i, 2] * s;
}
private static float s_curve(float t)
{
return t * t * (3f - 2f * t);
}
}
}