heman_image* heman_ops_warp_core(heman_image* img, heman_image* secondary,
int seed, int octaves)
{
struct osn_context* ctx;
open_simplex_noise(seed, &ctx);
int width = img->width;
int height = img->height;
int nbands = img->nbands;
heman_image* result = heman_image_create(width, height, nbands);
heman_image* result2 = secondary ? heman_image_create(width, height, secondary->nbands) : 0;
HEMAN_FLOAT invw = 1.0 / width;
HEMAN_FLOAT invh = 1.0 / height;
HEMAN_FLOAT inv = MIN(invw, invh);
HEMAN_FLOAT aspect = (float) width / height;
float gain = 0.6;
float lacunarity = 2.0;
float initial_amplitude = 0.05;
float initial_frequency = 8.0;
#pragma omp parallel for
for (int y = 0; y < height; y++) {
HEMAN_FLOAT* dst = result->data + y * width * nbands;
for (int x = 0; x < width; x++) {
float a = initial_amplitude;
float f = initial_frequency;
HEMAN_FLOAT* src;
// This is a little hack that modulates noise according to
// elevation, to prevent "swimming" at high elevations.
if (nbands == 4) {
src = heman_image_texel(img, x, y);
HEMAN_FLOAT elev = 1 - src[3];
a *= pow(elev, 4);
}
float s = x * inv;
float t = y * inv;
float u = x * invw;
float v = y * invh;
for (int i = 0; i < octaves; i++) {
u += NOISEX(s, t, a, f);
v += aspect * NOISEY(s, t, a, f);
a *= gain;
f *= lacunarity;
}
int i = CLAMP(u * width, 0, width - 1);
int j = CLAMP(v * height, 0, height - 1);
src = heman_image_texel(img, i, j);
for (int n = 0; n < nbands; n++) {
*dst++ = *src++;
}
if (secondary) {
src = heman_image_texel(secondary, x, y);
HEMAN_FLOAT* dst2 = heman_image_texel(result2, i, j);
for (int n = 0; n < secondary->nbands; n++) {
*dst2++ = *src++;
}
}
}
}
open_simplex_noise_free(ctx);
if (secondary) {
free(secondary->data);
secondary->data = result2->data;
free(result2);
}
return result;
}
OsnNoise::~OsnNoise() {
if (_context) {
open_simplex_noise_free(_context);
}
}
