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/**
* @file llperlin.cpp
*
* Copyright (c) 2001-$CurrentYear$, Linden Research, Inc.
* $License$
*/
#include "linden_common.h"
#include "llmath.h"
#include "llperlin.h"
#define B 0x100
#define BM 0xff
#define N 0x1000
#define NF32 (4096.f)
#define NP 12 /* 2^N */
#define NM 0xfff
static S32 p[B + B + 2];
static F32 g3[B + B + 2][3];
static F32 g2[B + B + 2][2];
static F32 g1[B + B + 2];
bool LLPerlinNoise::sInitialized = 0;
static void normalize2(F32 v[2])
{
F32 s = 1.f/(F32)sqrt(v[0] * v[0] + v[1] * v[1]);
v[0] = v[0] * s;
v[1] = v[1] * s;
}
static void normalize3(F32 v[3])
{
F32 s = 1.f/(F32)sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]);
v[0] = v[0] * s;
v[1] = v[1] * s;
v[2] = v[2] * s;
}
static void fast_setup(F32 vec, U8 &b0, U8 &b1, F32 &r0, F32 &r1)
{
S32 t_S32;
r1 = vec + NF32;
t_S32 = lltrunc(r1);
b0 = (U8)t_S32;
b1 = b0 + 1;
r0 = r1 - t_S32;
r1 = r0 - 1.f;
}
void LLPerlinNoise::init(void)
{
int i, j, k;
for (i = 0 ; i < B ; i++)
{
p[i] = i;
g1[i] = (F32)((rand() % (B + B)) - B) / B;
for (j = 0 ; j < 2 ; j++)
g2[i][j] = (F32)((rand() % (B + B)) - B) / B;
normalize2(g2[i]);
for (j = 0 ; j < 3 ; j++)
g3[i][j] = (F32)((rand() % (B + B)) - B) / B;
normalize3(g3[i]);
}
while (--i)
{
k = p[i];
p[i] = p[j = rand() % 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];
}
sInitialized = true;
}
//============================================================================
// Noise functions
#define s_curve(t) ( t * t * (3.f - 2.f * t) )
#define lerp_m(t, a, b) ( a + t * (b - a) )
F32 LLPerlinNoise::noise1(F32 x)
{
int bx0, bx1;
F32 rx0, rx1, sx, t, u, v;
if (!sInitialized)
init();
t = x + N;
bx0 = (lltrunc(t)) & BM;
bx1 = (bx0+1) & BM;
rx0 = t - lltrunc(t);
rx1 = rx0 - 1.f;
sx = s_curve(rx0);
u = rx0 * g1[ p[ bx0 ] ];
v = rx1 * g1[ p[ bx1 ] ];
return lerp_m(sx, u, v);
}
static F32 fast_at2(F32 rx, F32 ry, F32 *q)
{
return rx * q[0] + ry * q[1];
}
F32 LLPerlinNoise::noise2(F32 x, F32 y)
{
U8 bx0, bx1, by0, by1;
U32 b00, b10, b01, b11;
F32 rx0, rx1, ry0, ry1, *q, sx, sy, a, b, u, v;
S32 i, j;
if (!sInitialized)
init();
fast_setup(x, bx0, bx1, rx0, rx1);
fast_setup(y, by0, by1, ry0, ry1);
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);
q = *(g2 + b00);
u = fast_at2(rx0, ry0, q);
q = *(g2 + b10);
v = fast_at2(rx1, ry0, q);
a = lerp_m(sx, u, v);
q = *(g2 + b01);
u = fast_at2(rx0,ry1,q);
q = *(g2 + b11);
v = fast_at2(rx1,ry1,q);
b = lerp_m(sx, u, v);
return lerp_m(sy, a, b);
}
static F32 fast_at3(F32 rx, F32 ry, F32 rz, F32 *q)
{
return rx * q[0] + ry * q[1] + rz * q[2];
}
F32 LLPerlinNoise::noise3(F32 x, F32 y, F32 z)
{
U8 bx0, bx1, by0, by1, bz0, bz1;
S32 b00, b10, b01, b11;
F32 rx0, rx1, ry0, ry1, rz0, rz1, *q, sy, sz, a, b, c, d, t, u, v;
S32 i, j;
if (!sInitialized)
init();
fast_setup(x, bx0,bx1, rx0,rx1);
fast_setup(y, by0,by1, ry0,ry1);
fast_setup(z, bz0,bz1, rz0,rz1);
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);
q = g3[ b00 + bz0 ];
u = fast_at3(rx0,ry0,rz0,q);
q = g3[ b10 + bz0 ];
v = fast_at3(rx1,ry0,rz0,q);
a = lerp_m(t, u, v);
q = g3[ b01 + bz0 ];
u = fast_at3(rx0,ry1,rz0,q);
q = g3[ b11 + bz0 ];
v = fast_at3(rx1,ry1,rz0,q);
b = lerp_m(t, u, v);
c = lerp_m(sy, a, b);
q = g3[ b00 + bz1 ];
u = fast_at3(rx0,ry0,rz1,q);
q = g3[ b10 + bz1 ];
v = fast_at3(rx1,ry0,rz1,q);
a = lerp_m(t, u, v);
q = g3[ b01 + bz1 ];
u = fast_at3(rx0,ry1,rz1,q);
q = g3[ b11 + bz1 ];
v = fast_at3(rx1,ry1,rz1,q);
b = lerp_m(t, u, v);
d = lerp_m(sy, a, b);
return lerp_m(sz, c, d);
}
F32 LLPerlinNoise::turbulence2(F32 x, F32 y, F32 freq)
{
F32 t, lx, ly;
for (t = 0.f ; freq >= 1.f ; freq *= 0.5f)
{
lx = freq * x;
ly = freq * y;
t += noise2(lx, ly)/freq;
}
return t;
}
F32 LLPerlinNoise::turbulence3(F32 x, F32 y, F32 z, F32 freq)
{
F32 t, lx, ly, lz;
for (t = 0.f ; freq >= 1.f ; freq *= 0.5f)
{
lx = freq * x;
ly = freq * y;
lz = freq * z;
t += noise3(lx,ly,lz)/freq;
// t += fabs(noise3(lx,ly,lz)) / freq; // Like snow - bubbly at low frequencies
// t += sqrt(fabs(noise3(lx,ly,lz))) / freq; // Better at low freq
// t += (noise3(lx,ly,lz)*noise3(lx,ly,lz)) / freq;
}
return t;
}
F32 LLPerlinNoise::clouds3(F32 x, F32 y, F32 z, F32 freq)
{
F32 t, lx, ly, lz;
for (t = 0.f ; freq >= 1.f ; freq *= 0.5f)
{
lx = freq * x;
ly = freq * y;
lz = freq * z;
// t += noise3(lx,ly,lz)/freq;
// t += fabs(noise3(lx,ly,lz)) / freq; // Like snow - bubbly at low frequencies
// t += sqrt(fabs(noise3(lx,ly,lz))) / freq; // Better at low freq
t += (noise3(lx,ly,lz)*noise3(lx,ly,lz)) / freq;
}
return t;
}
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