Expose the perlin class publically
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140
perlin.cpp
140
perlin.cpp
@ -34,78 +34,78 @@
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#define LERP(a,b,t) lerp::quintic (a, b, t)
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struct params {
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typedef size_t seed_t;
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unsigned octaves;
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double persistence;
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double frequency;
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seed_t seed;
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// Just a random generator [-1.0, 1.0]
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double
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generate (intmax_t x, intmax_t y) const {
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intmax_t n = x + 257 * y;
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n = (n << 13U) ^ n ^ (intmax_t)seed;
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return (1.0 - ((n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0);
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}
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double
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eval (double x, double y) const {
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intmax_t x_int = intmax_t (x);
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double x_fac = x - x_int;
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intmax_t y_int = intmax_t (y);
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double y_fac = y - y_int;
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// Generate the four corner values
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double p0 = generate (x_int, y_int);
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double p1 = generate (x_int + 1, y_int);
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double p2 = generate (x_int, y_int + 1);
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double p3 = generate (x_int + 1, y_int + 1);
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// Interpolate on one dimension, then the other.
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return LERP (LERP (p0, p1, x_fac),
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LERP (p2, p3, x_fac),
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y_fac);
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}
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double
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sample (double x, double y) const {
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double total = 0.0;
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for (size_t i = 0; i < octaves; ++i) {
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double f = frequency * powf (2.0, i);
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double amplitude = powf (persistence, i);
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total += eval (x * f, y * f) * amplitude;
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total = max (-1.0, min (1.0, total));
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}
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return (1.0 + total) / 2.0;
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}
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params ():
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octaves (3),
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persistence (0.5),
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frequency (25.0),
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seed (util::random<size_t> ())
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{ ; }
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};
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static void
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perlin2d (uint8_t *restrict pixels, size_t width, size_t height, const params& p) {
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for (size_t y = 0; y < height; ++y)
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for (size_t x = 0; x < width; ++x) {
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double v = p.sample (x / double (width), y / double (height)); /*perlin2d (x / double (width),
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y / double (height),
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(size_t)pixels);*/
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pixels[x + y * width] = v * std::numeric_limits<uint8_t>::max ();
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}
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// Just a random generator [-1.0, 1.0]
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double
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util::perlin::generate (intmax_t x, intmax_t y) const {
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intmax_t n = x + 257 * y;
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n = (n << 13U) ^ n ^ (intmax_t)seed;
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return (1.0 - ((n * (n * n * 15731 + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0);
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}
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double
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util::perlin::eval (double x, double y) const {
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intmax_t x_int = intmax_t (x);
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double x_fac = x - x_int;
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intmax_t y_int = intmax_t (y);
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double y_fac = y - y_int;
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// Generate the four corner values
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double p0 = generate (x_int, y_int);
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double p1 = generate (x_int + 1, y_int);
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double p2 = generate (x_int, y_int + 1);
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double p3 = generate (x_int + 1, y_int + 1);
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// Interpolate on one dimension, then the other.
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return LERP (LERP (p0, p1, x_fac),
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LERP (p2, p3, x_fac),
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y_fac);
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}
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double
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util::perlin::sample (double x, double y) const {
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double total = 0.0;
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for (size_t i = 0; i < octaves; ++i) {
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double f = frequency * powf (2.0, i);
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double amplitude = powf (persistence, i);
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total += eval (x * f, y * f) * amplitude;
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total = max (-1.0, min (1.0, total));
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}
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return (1.0 + total) / 2.0;
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}
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util::perlin::perlin ():
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octaves (3),
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frequency (25.0),
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persistence (0.5),
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seed (util::random<size_t> ())
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{ ; }
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util::perlin::perlin (unsigned _octaves,
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double _frequency,
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double _persistence,
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seed_t _seed):
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octaves (_octaves),
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frequency (_frequency),
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persistence (_persistence),
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seed (_seed)
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{ ; }
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void
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perlin2d (uint8_t *restrict pixels, size_t width, size_t height) {
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perlin2d (pixels, width, height, params ());
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util::perlin2d (uint8_t *restrict pixels,
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size_t width,
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size_t height,
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const perlin &p) {
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for (size_t y = 0; y < height; ++y)
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for (size_t x = 0; x < width; ++x) {
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double v = p.sample (x / double (width), y / double (height));
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pixels[x + y * width] = v * std::numeric_limits<uint8_t>::max ();
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}
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}
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26
perlin.hpp
26
perlin.hpp
@ -24,6 +24,30 @@
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#include <cstdlib>
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void perlin2d (uint8_t *restrict pixels, size_t width, size_t height);
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namespace util {
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struct perlin {
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typedef size_t seed_t;
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unsigned octaves;
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double frequency;
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double persistence;
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seed_t seed;
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perlin ();
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perlin (unsigned octaves,
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double frequency,
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double persistence,
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seed_t seed);
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double sample (double x, double y) const;
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protected:
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double generate (intmax_t x, intmax_t y) const;
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double eval (double x, double y) const;
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};
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void perlin2d (uint8_t *restrict pixels, size_t width, size_t height, const perlin&);
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}
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#endif
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