lavfi: add Perlin noise generator

2025-11-23 21:54:53 +02:00 · 2024-05-27 11:19:08 +02:00
parent c9151ea507
commit 3764b8ecdb
7 changed files with 597 additions and 0 deletions
--- a/libavfilter/perlin.h
+++ b/libavfilter/perlin.h
@@ -0,0 +1,101 @@
+/*
+ * Perlin noise generator
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file
+ * Perlin Noise generator
+ */
+
+#ifndef AVFILTER_PERLIN_H
+#define AVFILTER_PERLIN_H
+
+#include <stdint.h>
+
+enum FFPerlinRandomMode {
+    FF_PERLIN_RANDOM_MODE_RANDOM,
+    FF_PERLIN_RANDOM_MODE_KEN,
+    FF_PERLIN_RANDOM_MODE_SEED,
+    FF_PERLIN_RANDOM_MODE_NB
+};
+
+/**
+ * Perlin generator context. This needs to be initialized with the
+ * parameters used to generate the Perlin noise.
+ */
+typedef struct FFPerlin {
+    /**
+     * spatial repeat period, if negative it is ignored
+     */
+    double period;
+
+    /**
+     * total number of components making up the noise, each one with
+     * doubled frequency
+     */
+    int octaves;
+
+    /**
+     * ratio used to compute the amplitude of the next octave
+     * component with respect to the previous component
+     */
+    double persistence;
+
+    /**
+     * permutations array used to compute the Perlin noise hash
+     */
+    uint8_t permutations[512];
+
+    /**
+     * define how to compute the permutations array
+     */
+    enum FFPerlinRandomMode random_mode;
+
+    /**
+     * when random_mode is set FF_PERLIN_RANDOM_MODE_RANDOM, set random
+     * seed used to compute the permutations array
+     */
+    unsigned int random_seed;
+} FFPerlin;
+
+/**
+ * Initialize the Perlin noise generator with parameters.
+ *
+ * @param perlin Perlin noise generator context
+ * @param period spatial repeat period, if negative it is ignored
+ * @param octaves total number of components making up the noise, each one with doubled frequency
+ * @param persistence define ratio used to compute the amplitude of the next octave
+ *                    component with respect to the previous component
+ * @param random_mode define how to compute the permutations array
+ * @param random_seed when random_mode is set to FF_PERLIN_RANDOM_MODE_RANDOM, set random
+ *                    seed used to compute the permutations array
+ * @return a negative AVERROR code in case of error, a non negative value otherwise
+ */
+int ff_perlin_init(FFPerlin *perlin, double period, int octaves, double persistence,
+                   enum FFPerlinRandomMode random_mode, unsigned int random_seed);
+
+/**
+ * Compute Perlin noise given the x, y, z coordinates.
+ *
+ * @param perlin Perlin noise generator context
+ * @return normalized value for the perlin noise, in the range [0, 1]
+ */
+double ff_perlin_get(FFPerlin *perlin, double x, double y, double z);
+
+#endif  /* AVFILTER_PERLIN_H */