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Expose the perlin class publically

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This commit is contained in:
Danny Robson 2012-05-17 14:37:56 +10:00
parent 3b8f4597bf
commit fd64e95a7d
2 changed files with 95 additions and 71 deletions
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140
perlin.cpp
View File

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

26
perlin.hpp
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@ -24,6 +24,30 @@
#include <cstdlib>
void perlin2d (uint8_t *restrict pixels, size_t width, size_t height);
namespace util {
struct perlin {
typedef size_t seed_t;
unsigned octaves;
double frequency;
double persistence;
seed_t seed;
perlin ();
perlin (unsigned octaves,
double frequency,
double persistence,
seed_t seed);
double sample (double x, double y) const;
protected:
double generate (intmax_t x, intmax_t y) const;
double eval (double x, double y) const;
};
void perlin2d (uint8_t *restrict pixels, size_t width, size_t height, const perlin&);
}
#endif