198 lines
4.4 KiB
C++
198 lines
4.4 KiB
C++
#include "NoiseFunctionPerlin.h"
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/*
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* Perlin noise implementation.
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*
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* Based on Ken Perlin implementation.
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*/
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#include <cmath>
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#include <cstdlib>
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NoiseFunctionPerlin::NoiseFunctionPerlin() {
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}
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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 double g3[B + B + 2][3];
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static double g2[B + B + 2][2];
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static double g1[B + B + 2];
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#define s_curve(t) (t * t * (3. - 2. * t))
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#define lerp(t, a, b) (a + t * (b - a))
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#define setup(i, b0, b1, r0, r1) \
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t = vec[i] + N; \
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b0 = trunc_to_int(t) & BM; \
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b1 = (b0 + 1) & BM; \
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r0 = t - trunc_to_int(t); \
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r1 = r0 - 1.;
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double noisePerlinGet1DValue(double x) {
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double vec[1] = {x * 2.0};
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int bx0, bx1;
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double rx0, rx1, sx, t, u, v;
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setup(0, bx0, bx1, rx0, rx1);
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sx = s_curve(rx0);
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u = rx0 * g1[p[bx0]];
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v = rx1 * g1[p[bx1]];
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return lerp(sx, u, v) * 1.068 + 0.5;
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}
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double noisePerlinGet2DValue(double x, double y) {
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double vec[2] = {x * 2.0, y * 2.0};
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int bx0, bx1, by0, by1, b00, b10, b01, b11;
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double rx0, rx1, ry0, ry1, *q, sx, sy, a, b, 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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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];
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u = at2(rx0, ry0);
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q = g2[b10];
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v = at2(rx1, ry0);
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a = lerp(sx, u, v);
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q = g2[b01];
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u = at2(rx0, ry1);
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q = g2[b11];
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v = at2(rx1, ry1);
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b = lerp(sx, u, v);
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return lerp(sy, a, b) * 0.709 + 0.5;
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}
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double noisePerlinGet3DValue(double x, double y, double z) {
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double vec[3] = {x * 2.0, y * 2.0, z * 2.0};
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int bx0, bx1, by0, by1, bz0, bz1, b00, b10, b01, b11;
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double 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];
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u = at3(rx0, ry0, rz0);
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q = g3[b10 + bz0];
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v = at3(rx1, ry0, rz0);
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a = lerp(t, u, v);
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q = g3[b01 + bz0];
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u = at3(rx0, ry1, rz0);
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q = g3[b11 + bz0];
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v = at3(rx1, ry1, rz0);
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b = lerp(t, u, v);
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c = lerp(sy, a, b);
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q = g3[b00 + bz1];
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u = at3(rx0, ry0, rz1);
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q = g3[b10 + bz1];
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v = at3(rx1, ry0, rz1);
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a = lerp(t, u, v);
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q = g3[b01 + bz1];
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u = at3(rx0, ry1, rz1);
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q = g3[b11 + bz1];
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v = at3(rx1, ry1, rz1);
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b = lerp(t, u, v);
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d = lerp(sy, a, b);
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return lerp(sz, c, d) * 0.661 + 0.5;
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}
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static void _normalize2(double v[2]) {
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double s;
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s = 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(double v[3]) {
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double s;
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s = 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 int noisePerlinInit(void) {
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int i, j, k;
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for (i = 0; i < B; i++) {
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p[i] = i;
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g1[i] = to_double((rand() % (B + B)) - B) / B;
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for (j = 0; j < 2; j++)
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g2[i][j] = to_double((rand() % (B + B)) - B) / B;
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_normalize2(g2[i]);
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for (j = 0; j < 3; j++)
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g3[i][j] = to_double((rand() % (B + B)) - B) / B;
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_normalize3(g3[i]);
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}
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while (--i) {
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k = p[i];
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p[i] = p[j = rand() % B];
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p[j] = k;
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}
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for (i = 0; i < B + 2; i++) {
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p[B + i] = p[i];
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g1[B + i] = g1[i];
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for (j = 0; j < 2; j++)
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g2[B + i][j] = g2[i][j];
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for (j = 0; j < 3; j++)
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g3[B + i][j] = g3[i][j];
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}
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return 1;
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}
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static int _inited = noisePerlinInit();
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