334 lines
5.8 KiB
C++
334 lines
5.8 KiB
C++
#include <stdlib.h>
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#include <stdio.h>
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#include <math.h>
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#include "mathlib.h"
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#include "vecmath.h"
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#include "perlin.h"
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float bias(float a, float b)
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{
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return (float) pow(a, log(b) / log(0.5));
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}
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float gain(float a, float b)
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{
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float p = (float) (log(1.0 - b) / log(0.5));
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if (a < 0.001f)
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return 0.0f;
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else if (a > 0.999f)
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return 1.0f;
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if (a < 0.5f)
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return (float) pow(2 * a, p) / 2;
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else
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return 1.0f - (float) pow(2 * (1.0 - a), p) / 2;
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}
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float noise(float vec[], int len)
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{
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switch (len) {
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case 0:
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return 0.;
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case 1:
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return noise1(vec[0]);
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case 2:
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return noise2(vec);
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default:
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return noise3(vec);
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}
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}
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float turbulence(float v[], float freq)
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{
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float t, vec[3];
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for (t = 0. ; freq >= 1. ; freq /= 2) {
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vec[0] = freq * v[0];
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vec[1] = freq * v[1];
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vec[2] = freq * v[2];
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t += (float) fabs(noise3(vec)) / freq;
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}
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return t;
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}
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float turbulence(Point2f& p, float freq)
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{
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float t;
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float vec[2];
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for (t = 0.0f; freq >= 1.0f; freq *= 0.5f)
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{
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vec[0] = freq * p.x;
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vec[1] = freq * p.y;
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t += (float) fabs(noise2(vec)) / freq;
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}
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return t;
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}
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float turbulence(Point3f& p, float freq)
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{
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float t;
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float vec[3];
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for (t = 0.0f; freq >= 1.0f; freq *= 0.5f)
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{
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vec[0] = freq * p.x;
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vec[1] = freq * p.y;
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vec[2] = freq * p.z;
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t += (float) fabs(noise3(vec)) / freq;
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}
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return t;
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}
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float fractalsum(float v[], float freq)
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{
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float t;
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float vec[3];
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for (t = 0.0f ; freq >= 1.0f ; freq /= 2.0f) {
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vec[0] = freq * v[0];
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vec[1] = freq * v[1];
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vec[2] = freq * v[2];
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t += noise3(vec) / freq;
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}
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return t;
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}
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float fractalsum(Point2f& p, float freq)
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{
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float t;
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float vec[2];
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for (t = 0.0f; freq >= 1.0f; freq *= 0.5f)
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{
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vec[0] = freq * p.x;
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vec[1] = freq * p.y;
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t += noise2(vec) / freq;
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}
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return t;
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}
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float fractalsum(Point3f& p, float freq)
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{
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float t;
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float vec[3];
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for (t = 0.0f; freq >= 1.0f; freq *= 0.5f)
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{
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vec[0] = freq * p.x;
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vec[1] = freq * p.y;
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vec[2] = freq * p.z;
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t += noise3(vec) / freq;
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}
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return t;
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}
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/* noise functions over 1, 2, and 3 dimensions */
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#define B 0x100
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#define BM 0xff
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#define N 0x1000
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#define NP 12 /* 2^N */
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#define NM 0xfff
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static int p[B + B + 2];
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static float g3[B + B + 2][3];
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static float g2[B + B + 2][2];
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static float g1[B + B + 2];
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static bool initialized = false;
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static void init(void);
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#define s_curve(t) ( t * t * (3.0f - 2.0f * t) )
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#define setup(i, b0, b1, r0, r1) \
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t = vec[i] + N;\
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b0 = ((int)t) & BM;\
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b1 = (b0+1) & BM;\
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r0 = t - (int)t;\
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r1 = r0 - 1.0f;
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float noise1(float arg)
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{
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if (!initialized)
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init();
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int bx0, bx1;
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float rx0, rx1, t, u, v, vec[1];
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vec[0] = arg;
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setup(0, bx0, bx1, rx0, rx1);
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u = rx0 * g1[p[bx0]];
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v = rx1 * g1[p[bx1]];
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return Mathf::lerp(s_curve(rx0), u, v);
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}
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float noise2(float vec[2])
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{
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int bx0, bx1, by0, by1, b00, b10, b01, b11;
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float rx0, rx1, ry0, ry1, *q, sx, sy, a, b, t, u, v;
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int i, j;
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if (!initialized)
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init();
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setup(0, bx0,bx1, rx0,rx1);
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setup(1, by0,by1, ry0,ry1);
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i = p[ bx0 ];
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j = p[ bx1 ];
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b00 = p[ i + by0 ];
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b10 = p[ j + by0 ];
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b01 = p[ i + by1 ];
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b11 = p[ j + by1 ];
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sx = s_curve(rx0);
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sy = s_curve(ry0);
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#define at2(rx,ry) ( rx * q[0] + ry * q[1] )
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q = g2[ b00 ] ; u = at2(rx0,ry0);
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q = g2[ b10 ] ; v = at2(rx1,ry0);
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a = Mathf::lerp(sx, u, v);
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q = g2[ b01 ] ; u = at2(rx0,ry1);
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q = g2[ b11 ] ; v = at2(rx1,ry1);
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b = Mathf::lerp(sx, u, v);
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return Mathf::lerp(sy, a, b);
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}
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float noise3(float vec[3])
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{
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if (!initialized)
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init();
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int bx0, bx1, by0, by1, bz0, bz1, b00, b10, b01, b11;
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float rx0, rx1, ry0, ry1, rz0, rz1, *q, sy, sz, a, b, c, d, t, u, v;
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int i, j;
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setup(0, bx0,bx1, rx0,rx1);
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setup(1, by0,by1, ry0,ry1);
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setup(2, bz0,bz1, rz0,rz1);
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i = p[ bx0 ];
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j = p[ bx1 ];
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b00 = p[ i + by0 ];
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b10 = p[ j + by0 ];
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b01 = p[ i + by1 ];
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b11 = p[ j + by1 ];
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t = s_curve(rx0);
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sy = s_curve(ry0);
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sz = s_curve(rz0);
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#define at3(rx,ry,rz) ( rx * q[0] + ry * q[1] + rz * q[2] )
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q = g3[ b00 + bz0 ] ; u = at3(rx0,ry0,rz0);
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q = g3[ b10 + bz0 ] ; v = at3(rx1,ry0,rz0);
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a = Mathf::lerp(t, u, v);
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q = g3[ b01 + bz0 ] ; u = at3(rx0,ry1,rz0);
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q = g3[ b11 + bz0 ] ; v = at3(rx1,ry1,rz0);
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b = Mathf::lerp(t, u, v);
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c = Mathf::lerp(sy, a, b);
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q = g3[ b00 + bz1 ] ; u = at3(rx0,ry0,rz1);
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q = g3[ b10 + bz1 ] ; v = at3(rx1,ry0,rz1);
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a = Mathf::lerp(t, u, v);
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q = g3[ b01 + bz1 ] ; u = at3(rx0,ry1,rz1);
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q = g3[ b11 + bz1 ] ; v = at3(rx1,ry1,rz1);
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b = Mathf::lerp(t, u, v);
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d = Mathf::lerp(sy, a, b);
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return Mathf::lerp(sz, c, d);
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}
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static void normalize2(float v[2])
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{
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float s = (float) sqrt(v[0] * v[0] + v[1] * v[1]);
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v[0] = v[0] / s;
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v[1] = v[1] / s;
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}
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static void normalize3(float v[3])
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{
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float s = (float) sqrt(v[0] * v[0] + v[1] * v[1] + v[2] * v[2]);
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v[0] = v[0] / s;
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v[1] = v[1] / s;
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v[2] = v[2] / s;
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}
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static void init()
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{
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int i, j, k;
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for (i = 0; i < B; i++)
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{
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g1[i] = Mathf::sfrand();
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g2[i][0] = Mathf::sfrand();
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g2[i][1] = Mathf::sfrand();
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normalize2(g2[i]);
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g3[i][0] = Mathf::sfrand();
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g3[i][1] = Mathf::sfrand();
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g3[i][2] = Mathf::sfrand();
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normalize3(g3[i]);
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}
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// Fill the permutation array with values . . .
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for (i = 0; i < B; i++)
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p[i] = i;
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// . . . and then shuffle it
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for (i = 0; i < B; i++)
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{
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k = p[i];
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j = rand() % B;
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p[i] = p[j];
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p[j] = k;
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}
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// Duplicate values to accelerate table lookups
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for (i = 0; i < B + 2; i++)
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{
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p[B + i] = p[i];
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g1[B + i] = g1[i];
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g2[B + i][0] = g2[i][0];
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g2[B + i][1] = g2[i][1];
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g3[B + i][0] = g3[i][0];
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g3[B + i][1] = g3[i][1];
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g3[B + i][2] = g3[i][2];
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}
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initialized = true;
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}
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