| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | /* | ||
| 2 | * This file is part of FFmpeg. | ||
| 3 | * | ||
| 4 | * FFmpeg is free software; you can redistribute it and/or modify | ||
| 5 | * it under the terms of the GNU General Public License as published by | ||
| 6 | * the Free Software Foundation; either version 2 of the License, or | ||
| 7 | * (at your option) any later version. | ||
| 8 | * | ||
| 9 | * FFmpeg is distributed in the hope that it will be useful, | ||
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| 12 | * GNU General Public License for more details. | ||
| 13 | * | ||
| 14 | * You should have received a copy of the GNU General Public License along | ||
| 15 | * with FFmpeg; if not, write to the Free Software Foundation, Inc., | ||
| 16 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 17 | */ | ||
| 18 | |||
| 19 | /** | ||
| 20 | * @file | ||
| 21 | * Perlin Noise generator, based on code from: | ||
| 22 | * https://adrianb.io/2014/08/09/perlinnoise.html | ||
| 23 | * | ||
| 24 | * Original article from Ken Perlin: | ||
| 25 | * http://mrl.nyu.edu/~perlin/paper445.pdf | ||
| 26 | */ | ||
| 27 | |||
| 28 | #include <math.h> | ||
| 29 | |||
| 30 | #include "libavutil/lfg.h" | ||
| 31 | #include "libavutil/random_seed.h" | ||
| 32 | #include "perlin.h" | ||
| 33 | |||
| 34 | ✗ | static inline int inc(int num, int period) | |
| 35 | { | ||
| 36 | ✗ | num++; | |
| 37 | ✗ | if (period > 0) | |
| 38 | ✗ | num %= period; | |
| 39 | ✗ | return num; | |
| 40 | } | ||
| 41 | |||
| 42 | ✗ | static inline double grad(int hash, double x, double y, double z) | |
| 43 | { | ||
| 44 | // Take the hashed value and take the first 4 bits of it (15 == 0b1111) | ||
| 45 | ✗ | int h = hash & 15; | |
| 46 | // If the most significant bit (MSB) of the hash is 0 then set u = x. Otherwise y. | ||
| 47 | ✗ | double u = h < 8 /* 0b1000 */ ? x : y; | |
| 48 | double v; | ||
| 49 | |||
| 50 | // In Ken Perlin's original implementation this was another | ||
| 51 | // conditional operator (?:), then expanded for readability. | ||
| 52 | ✗ | if (h < 4 /* 0b0100 */) | |
| 53 | // If the first and second significant bits are 0 set v = y | ||
| 54 | ✗ | v = y; | |
| 55 | // If the first and second significant bits are 1 set v = x | ||
| 56 | ✗ | else if (h == 12 /* 0b1100 */ || h == 14 /* 0b1110 */) | |
| 57 | ✗ | v = x; | |
| 58 | else | ||
| 59 | // If the first and second significant bits are not equal (0/1, 1/0) set v = z | ||
| 60 | ✗ | v = z; | |
| 61 | |||
| 62 | // Use the last 2 bits to decide if u and v are positive or negative. Then return their addition. | ||
| 63 | ✗ | return ((h&1) == 0 ? u : -u)+((h&2) == 0 ? v : -v); | |
| 64 | } | ||
| 65 | |||
| 66 | ✗ | static inline double fade(double t) | |
| 67 | { | ||
| 68 | // Fade function as defined by Ken Perlin. This eases coordinate values | ||
| 69 | // so that they will "ease" towards integral values. This ends up smoothing | ||
| 70 | // the final output. | ||
| 71 | // use Horner method to compute: 6t^5 - 15t^4 + 10t^3 | ||
| 72 | ✗ | return t * t * t * (t * (t * 6 - 15) + 10); | |
| 73 | } | ||
| 74 | |||
| 75 | ✗ | static double lerp(double a, double b, double x) | |
| 76 | { | ||
| 77 | ✗ | return a + x * (b - a); | |
| 78 | } | ||
| 79 | |||
| 80 | // Hash lookup table as defined by Ken Perlin. This is a randomly | ||
| 81 | // arranged array of all numbers from 0-255 inclusive. | ||
| 82 | static uint8_t ken_permutations[] = { | ||
| 83 | 151, 160, 137, 91, 90, 15, 131, 13, 201, 95, 96, 53, 194, 233, 7, 225, | ||
| 84 | 140, 36, 103, 30, 69, 142, 8, 99, 37, 240, 21, 10, 23, 190, 6, 148, | ||
| 85 | 247, 120, 234, 75, 0, 26, 197, 62, 94, 252, 219, 203, 117, 35, 11, 32, | ||
| 86 | 57, 177, 33, 88, 237, 149, 56, 87, 174, 20, 125, 136, 171, 168, 68, 175, | ||
| 87 | 74, 165, 71, 134, 139, 48, 27, 166, 77, 146, 158, 231, 83, 111, 229, 122, | ||
| 88 | 60, 211, 133, 230, 220, 105, 92, 41, 55, 46, 245, 40, 244, 102, 143, 54, | ||
| 89 | 65, 25, 63, 161, 1, 216, 80, 73, 209, 76, 132, 187, 208, 89, 18, 169, | ||
| 90 | 200, 196, 135, 130, 116, 188, 159, 86, 164, 100, 109, 198, 173, 186, 3, 64, | ||
| 91 | 52, 217, 226, 250, 124, 123, 5, 202, 38, 147, 118, 126, 255, 82, 85, 212, | ||
| 92 | 207, 206, 59, 227, 47, 16, 58, 17, 182, 189, 28, 42, 223, 183, 170, 213, | ||
| 93 | 119, 248, 152, 2, 44, 154, 163, 70, 221, 153, 101, 155, 167, 43, 172, 9, | ||
| 94 | 129, 22, 39, 253, 19, 98, 108, 110, 79, 113, 224, 232, 178, 185, 112, 104, | ||
| 95 | 218, 246, 97, 228, 251, 34, 242, 193, 238, 210, 144, 12, 191, 179, 162, 241, | ||
| 96 | 81, 51, 145, 235, 249, 14, 239, 107, 49, 192, 214, 31, 181, 199, 106, 157, | ||
| 97 | 184, 84, 204, 176, 115, 121, 50, 45, 127, 4, 150, 254, 138, 236, 205, 93, | ||
| 98 | 222, 114, 67, 29, 24, 72, 243, 141, 128, 195, 78, 66, 215, 61, 156, 180 | ||
| 99 | }; | ||
| 100 | |||
| 101 | ✗ | int ff_perlin_init(FFPerlin *perlin, double period, int octaves, double persistence, | |
| 102 | enum FFPerlinRandomMode random_mode, unsigned int random_seed) | ||
| 103 | { | ||
| 104 | int i; | ||
| 105 | |||
| 106 | ✗ | perlin->period = period; | |
| 107 | ✗ | perlin->octaves = octaves; | |
| 108 | ✗ | perlin->persistence = persistence; | |
| 109 | ✗ | perlin->random_mode = random_mode; | |
| 110 | ✗ | perlin->random_seed = random_seed; | |
| 111 | |||
| 112 | ✗ | if (perlin->random_mode == FF_PERLIN_RANDOM_MODE_KEN) { | |
| 113 | ✗ | for (i = 0; i < 512; i++) { | |
| 114 | ✗ | perlin->permutations[i] = ken_permutations[i % 256]; | |
| 115 | } | ||
| 116 | } else { | ||
| 117 | AVLFG lfg; | ||
| 118 | uint8_t random_permutations[256]; | ||
| 119 | |||
| 120 | ✗ | if (perlin->random_mode == FF_PERLIN_RANDOM_MODE_RANDOM) | |
| 121 | ✗ | perlin->random_seed = av_get_random_seed(); | |
| 122 | |||
| 123 | ✗ | av_lfg_init(&lfg, perlin->random_seed); | |
| 124 | |||
| 125 | ✗ | for (i = 0; i < 256; i++) { | |
| 126 | ✗ | random_permutations[i] = i; | |
| 127 | } | ||
| 128 | |||
| 129 | ✗ | for (i = 0; i < 256; i++) { | |
| 130 | ✗ | unsigned int random_idx = av_lfg_get(&lfg) % (256-i); | |
| 131 | ✗ | uint8_t random_val = random_permutations[random_idx]; | |
| 132 | ✗ | random_permutations[random_idx] = random_permutations[255-i]; | |
| 133 | |||
| 134 | ✗ | perlin->permutations[i] = perlin->permutations[i+256] = random_val; | |
| 135 | } | ||
| 136 | } | ||
| 137 | |||
| 138 | ✗ | return 0; | |
| 139 | } | ||
| 140 | |||
| 141 | ✗ | static double perlin_get(FFPerlin *perlin, double x, double y, double z) | |
| 142 | { | ||
| 143 | int xi, yi, zi; | ||
| 144 | double xf, yf, zf; | ||
| 145 | double u, v, w; | ||
| 146 | ✗ | const uint8_t *p = perlin->permutations; | |
| 147 | ✗ | double period = perlin->period; | |
| 148 | int aaa, aba, aab, abb, baa, bba, bab, bbb; | ||
| 149 | double x1, x2, y1, y2; | ||
| 150 | |||
| 151 | ✗ | if (perlin->period > 0) { | |
| 152 | // If we have any period on, change the coordinates to their "local" repetitions | ||
| 153 | ✗ | x = fmod(x, perlin->period); | |
| 154 | ✗ | y = fmod(y, perlin->period); | |
| 155 | ✗ | z = fmod(z, perlin->period); | |
| 156 | } | ||
| 157 | |||
| 158 | // Calculate the "unit cube" that the point asked will be located in | ||
| 159 | // The left bound is ( |_x_|,|_y_|,|_z_| ) and the right bound is that | ||
| 160 | // plus 1. Next we calculate the location (from 0.0 to 1.0) in that cube. | ||
| 161 | ✗ | xi = (int)x & 255; | |
| 162 | ✗ | yi = (int)y & 255; | |
| 163 | ✗ | zi = (int)z & 255; | |
| 164 | |||
| 165 | ✗ | xf = x - (int)x; | |
| 166 | ✗ | yf = y - (int)y; | |
| 167 | ✗ | zf = z - (int)z; | |
| 168 | |||
| 169 | // We also fade the location to smooth the result. | ||
| 170 | ✗ | u = fade(xf); | |
| 171 | ✗ | v = fade(yf); | |
| 172 | ✗ | w = fade(zf); | |
| 173 | |||
| 174 | ✗ | aaa = p[p[p[ xi ] + yi ] + zi ]; | |
| 175 | ✗ | aba = p[p[p[ xi ] + inc(yi, period)] + zi ]; | |
| 176 | ✗ | aab = p[p[p[ xi ] + yi ] + inc(zi, period)]; | |
| 177 | ✗ | abb = p[p[p[ xi ] + inc(yi, period)] + inc(zi, period)]; | |
| 178 | ✗ | baa = p[p[p[inc(xi, period)] + yi ] + zi ]; | |
| 179 | ✗ | bba = p[p[p[inc(xi, period)] + inc(yi, period)] + zi ]; | |
| 180 | ✗ | bab = p[p[p[inc(xi, period)] + yi ] + inc(zi, period)]; | |
| 181 | ✗ | bbb = p[p[p[inc(xi, period)] + inc(yi, period)] + inc(zi, period)]; | |
| 182 | |||
| 183 | // The gradient function calculates the dot product between a pseudorandom | ||
| 184 | // gradient vector and the vector from the input coordinate to the 8 | ||
| 185 | // surrounding points in its unit cube. | ||
| 186 | // This is all then lerped together as a sort of weighted average based on the faded (u,v,w) | ||
| 187 | // values we made earlier. | ||
| 188 | ✗ | x1 = lerp(grad(aaa, xf , yf , zf), | |
| 189 | grad(baa, xf-1, yf , zf), | ||
| 190 | u); | ||
| 191 | ✗ | x2 = lerp(grad(aba, xf , yf-1, zf), | |
| 192 | grad(bba, xf-1, yf-1, zf), | ||
| 193 | u); | ||
| 194 | ✗ | y1 = lerp(x1, x2, v); | |
| 195 | |||
| 196 | ✗ | x1 = lerp(grad(aab, xf , yf , zf-1), | |
| 197 | grad(bab, xf-1, yf , zf-1), | ||
| 198 | u); | ||
| 199 | ✗ | x2 = lerp(grad(abb, xf , yf-1, zf-1), | |
| 200 | grad(bbb, xf-1, yf-1, zf-1), | ||
| 201 | u); | ||
| 202 | ✗ | y2 = lerp(x1, x2, v); | |
| 203 | |||
| 204 | // For convenience we bound it to 0 - 1 (theoretical min/max before is -1 - 1) | ||
| 205 | ✗ | return (lerp(y1, y2, w) + 1) / 2; | |
| 206 | } | ||
| 207 | |||
| 208 | ✗ | double ff_perlin_get(FFPerlin *perlin, double x, double y, double z) | |
| 209 | { | ||
| 210 | ✗ | double total = 0; | |
| 211 | ✗ | double frequency = 1; | |
| 212 | ✗ | double amplitude = 1; | |
| 213 | ✗ | double max_value = 0; // Used for normalizing result to 0.0 - 1.0 | |
| 214 | |||
| 215 | ✗ | for (int i = 0; i < perlin->octaves; i++) { | |
| 216 | ✗ | total += perlin_get(perlin, x * frequency, y * frequency, z * frequency) * amplitude; | |
| 217 | ✗ | max_value += amplitude; | |
| 218 | ✗ | amplitude *= perlin->persistence; | |
| 219 | ✗ | frequency *= 2; | |
| 220 | } | ||
| 221 | |||
| 222 | ✗ | return total / max_value; | |
| 223 | } | ||
| 224 | |||
| 225 |