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#include "include/perlin.h"
static float noise(int x, int y) //seed this??
{
int n;
n = x + y * 57 * 2749;
n = (n << 13) ^ n * 1087;
return (1.0 - ( (n * ((n * n * 15731) + 789221) + 1376312589) & 0x7fffffff) / 1073741824.0)*3433;
}
static float interpolate(float a, float b, float x)
{
float pi_mod;
float f_unk;
pi_mod = x * 3.1415927;
f_unk = (1 - cos(pi_mod)) * 0.5;
return (a * (1 - f_unk) + b * x);
}
static float smooth_noise(int x, int y)
{
float corners;
float center;
float sides;
corners = (noise(x - 1, y - 1) + noise(x + 1, y - 1) +
noise(x - 1, x + 1) + noise(x + 1, y + 1)) / 16;
sides = (noise(x - 1, y) + noise(x + 1, y) + noise(x, y - 1) +
noise(x, y + 1)) / 8;
center = noise(x, y) / 4;
return (corners + sides + center);
}
static float noise_handler(float x, float y)
{
int int_val[2];
float frac_val[2];
float value[4];
float res[2];
int_val[0] = (int)x;
int_val[1] = (int)y;
frac_val[0] = x - int_val[0];
frac_val[1] = y - int_val[1];
value[0] = smooth_noise(int_val[0], int_val[1]);
value[1] = smooth_noise(int_val[0] + 1, int_val[1]);
value[2] = smooth_noise(int_val[0], int_val[1] + 1);
value[3] = smooth_noise(int_val[0] + 1, int_val[1] + 1);
res[0] = interpolate(value[0], value[1], frac_val[0]);
res[1] = interpolate(value[2], value[3], frac_val[0]);
return (interpolate(res[0], res[1], frac_val[1]));
}
float perlin_noise(float x, float y) //implement Fractal Brownian Motion?
{
srand(time(NULL));
float total;
float per;
float amp;
int hz;
int octave;
total = 0.0;
per = 0.5;
octave = 10;
for(int i = 0; i < octave; i++)
{
hz = pow(2, i);
amp = pow(per, (float)i);
total += noise_handler(x * (float)hz, y * (float)hz) * amp;
}
return (total);
}
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