float PerlinNoise(float x, float y, int width, int octaves, int seed, double period) {
double a, b, value, freq, zone_x, zone_y;
int s, box, num, step_x, step_y;
float amplitude = period;
int noisedata;
freq = 1 / period;
value = 0;
for (s = 0; s<octaves; s++) {
num = static_cast<int>(width*freq);
step_x = static_cast<int>(x*freq);
step_y = static_cast<int>(y*freq);
zone_x = x*freq - step_x;
zone_y = y*freq - step_y;
box = step_x + step_y*num;
noisedata = (box + seed);
a = InterLinear(Noise(noisedata), Noise(noisedata + 1), zone_x);
b = InterLinear(Noise(noisedata + num), Noise(noisedata + 1 + num), zone_x);
value += InterLinear(a, b, zone_y)*amplitude;
freq *= 4;
amplitude /= 4;
}
return value;
}
/*! \brief Returns the exact value if x is a multiple of dx, else interpolated value.
*
* Interpolation method depends on InterpolType input. \n
* It is checked. Its expected values are TRU, LIN, CUB and LAG.
*
* \return
* \f[ \left\{ \begin{array}{ll}
TruncVal(x) & \textrm{if } modulo(\frac{x-x_0}{dx},1) \approx 0 \\
TruncVal(x) & \textrm{if } InterpolType = TRU \\
InterLinear(x) & \textrm{if } InterpolType = LIN \\
InterCubic(x) & \textrm{if } InterpolType = CUB \\
InterLagrange(x, int(InterpUtilValue)) & \textrm{if } InterpolType = LAG
\end{array} \right.\f]
*/
double Serie2::gData(double x, INTERP InterpolType, double InterpUtilValue)
{
//cout << "Serie2::gData :" << endl;
//cout << " fmod(xr,1.0) = " << fmod(xr,1.0) << endl;
xr = (x-x0)/dx ;
bin = MathUtils::ifloor(xr);
xrbinE = true;
//if(fmod((x-x0)/dx,1.0) < PRECISION){
//cout << " --> Tronque" << endl;
if((xr-bin) < PRECISION){
return(TruncVal(x));
}else{
switch(InterpolType){
case TRU :
return(TruncVal(x));
break;
case LIN :
return(InterLinear(x));
break;
case CUB :
return(InterCubic(x));
break;
case LAG :
return(InterLagrange(x, int(InterpUtilValue)));
break;
//case SIN :
// return(InterSincTrunc(x, int(InterpUtilValue)));
// break;
default :
throw invalid_argument("Serie2: No interpolation method !");
}
}
}