110 lines
5.1 KiB
C
110 lines
5.1 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/bits/bits.h"
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#include "libc/bits/initializer.internal.h"
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#include "libc/macros.h"
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#include "libc/math.h"
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#include "tool/viz/lib/graphic.h"
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static int perm[513];
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static double lerp(double t, double a, double b) {
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return a + t * (b - a);
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}
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static double fade(double t) {
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return t * t * t * (t * (t * 6.0 - 15.0) + 10.0);
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}
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static double grad(int hash, double x, double y, double z) {
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int h;
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double u, v;
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h = hash & 15;
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u = h < 8 ? x : y;
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v = h < 4 ? y : (h == 12 || h == 14) ? x : z;
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return ((h & 1) ? -u : u) + ((h & 2) ? -v : v);
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}
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/**
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* Perlin's improved noise algorithm.
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*
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* @see http://mrl.nyu.edu/~perlin/noise/
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* @note it's bryce3d cgi basically
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*/
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double perlin3(double x, double y, double z) /* clang-format off */ {
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double u, v, w;
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int X, Y, Z, AA, AB, BA, BB;
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X = floor(x);
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Y = floor(y);
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Z = floor(z);
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X &= 0xff;
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Y &= 0xff;
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Z &= 0xff;
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x -= floor(x);
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y -= floor(y);
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z -= floor(z);
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u = fade(x);
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v = fade(y);
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w = fade(z);
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AA = perm[perm[X ] + Y ] + Z;
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AB = perm[perm[X ] + Y + 1] + Z;
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BA = perm[perm[X + 1] + Y ] + Z;
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BB = perm[perm[X + 1] + Y + 1] + Z;
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return lerp(w, lerp(v, lerp(u, grad(perm[AA ], x , y , z ),
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grad(perm[BA ], x - 1, y , z )),
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lerp(u, grad(perm[AB ], x , y - 1, z ),
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grad(perm[BB ], x - 1, y - 1, z ))),
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lerp(v, lerp(u, grad(perm[AA + 1], x , y , z - 1),
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grad(perm[BA + 1], x - 1, y , z - 1)),
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lerp(u, grad(perm[AB + 1], x , y - 1, z - 1),
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grad(perm[BB + 1], x - 1, y - 1, z - 1))));
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} /* clang-format on */
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static const uint8_t kPerm[] = {
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151, 160, 137, 91, 90, 15, 131, 13, 201, 95, 96, 53, 194, 233, 7,
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225, 140, 36, 103, 30, 69, 142, 8, 99, 37, 240, 21, 10, 23, 190,
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6, 148, 247, 120, 234, 75, 0, 26, 197, 62, 94, 252, 219, 203, 117,
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35, 11, 32, 57, 177, 33, 88, 237, 149, 56, 87, 174, 20, 125, 136,
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171, 168, 68, 175, 74, 165, 71, 134, 139, 48, 27, 166, 77, 146, 158,
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231, 83, 111, 229, 122, 60, 211, 133, 230, 220, 105, 92, 41, 55, 46,
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245, 40, 244, 102, 143, 54, 65, 25, 63, 161, 1, 216, 80, 73, 209,
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76, 132, 187, 208, 89, 18, 169, 200, 196, 135, 130, 116, 188, 159, 86,
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164, 100, 109, 198, 173, 186, 3, 64, 52, 217, 226, 250, 124, 123, 5,
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202, 38, 147, 118, 126, 255, 82, 85, 212, 207, 206, 59, 227, 47, 16,
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58, 17, 182, 189, 28, 42, 223, 183, 170, 213, 119, 248, 152, 2, 44,
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154, 163, 70, 221, 153, 101, 155, 167, 43, 172, 9, 129, 22, 39, 253,
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19, 98, 108, 110, 79, 113, 224, 232, 178, 185, 112, 104, 218, 246, 97,
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228, 251, 34, 242, 193, 238, 210, 144, 12, 191, 179, 162, 241, 81, 51,
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145, 235, 249, 14, 239, 107, 49, 192, 214, 31, 181, 199, 106, 157, 184,
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84, 204, 176, 115, 121, 50, 45, 127, 4, 150, 254, 138, 236, 205, 93,
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222, 114, 67, 29, 24, 72, 243, 141, 128, 195, 78, 66, 215, 61, 156,
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180,
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};
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static nooptimize textstartup void init(void) {
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unsigned i;
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for (i = 0; i < 256; ++i) {
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perm[i] = kPerm[i];
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perm[i + 256] = kPerm[i];
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}
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}
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INITIALIZER(400, _init_perlin3, init());
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