public static double GradientNoise3D(
double fx, double fy, double fz, int ix, int iy, int iz, int seed) {
VectorTable vectorTable = new VectorTable();
// Randomly generate a gradient vector given the integer coordinates of the
// input value. This implementation generates a random number and uses it
// as an index into a normalized-vector lookup table.
int vectorIndex =
(X_NOISE_GEN * ix + Y_NOISE_GEN * iy + Z_NOISE_GEN * iz + SEED_NOISE_GEN * seed)
& 0xffffffff;
vectorIndex ^= (vectorIndex >> SHIFT_NOISE_GEN);
vectorIndex &= 0xff;
double xvGradient = vectorTable.getRandomVectors(vectorIndex, 0);
double yvGradient = vectorTable.getRandomVectors(vectorIndex, 1);
double zvGradient = vectorTable.getRandomVectors(vectorIndex, 2);
// array size too large when using this original, changed to above for all 3
// double zvGradient = vectorTable.getRandomVectors(vectorIndex << 2, 2);
// Set up us another vector equal to the distance between the two vectors
// passed to this function.
double xvPoint = (fx - (double) ix);
double yvPoint = (fy - (double) iy);
double zvPoint = (fz - (double) iz);
// Now compute the dot product of the gradient vector with the distance
// vector. The resulting value is gradient noise. Apply a scaling value
// so that this noise value ranges from -1.0 to 1.0.
return ((xvGradient * xvPoint) + (yvGradient * yvPoint) + (zvGradient * zvPoint)) * 2.12;
}
