float CPerlinNoise::interpolate_noise(float x, float y) const
{
static int integer_X;
static int integer_Y;
static float fractional_X;
static float fractional_Y;
static float v1, v2, v3, v4, i1, i2;
// separate integer & decimal x
integer_X = (int) x;
fractional_X = x - integer_X;
// separate integer & decimal y
integer_Y = (int) y;
fractional_Y = y - integer_Y;
// get 4 corners
v1 = smooth_noise(integer_X, integer_Y);
v2 = smooth_noise(integer_X + 1, integer_Y);
v3 = smooth_noise(integer_X, integer_Y + 1);
v4 = smooth_noise(integer_X + 1, integer_Y + 1);
// interpolate 4 corners
i1 = m_Interpolation(v1, v2, fractional_X);
i2 = m_Interpolation(v3, v4, fractional_X);
// interpolate 2 points
return m_Interpolation(i1, i2 ,fractional_Y);
}
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]));
}
double ft_perlin(double x, double y, double z)
{
double result;
double f;
double amplitude;
int i;
int t;
result = 0;
f = FREQUENCY;
amplitude = 1;
i = -1;
while (++i < OCTAVES)
{
t = i * 4096;
result += smooth_noise(x * f + t, y * f + t, z * f + t) * amplitude;
amplitude *= PERSISTANCE;
f *= 2;
}
result *= (1 - PERSISTANCE) / (1 - amplitude);
return (result);
}