// I/F
public float Sample(float x, float y, float z)
{
if (!initialized)
{
Reseed();
}
int fx = MathExtension.Floor(x);
int fy = MathExtension.Floor(y);
int fz = MathExtension.Floor(z);
// Find unit cube that contains point.
int cx = fx & modMask;
int cy = fy & modMask;
int cz = fz & modMask;
// Find relative x, y, z of point in cube.
var rx = x - fx;
var ry = y - fy;
var rz = z - fz;
// complute fade curves for each of x, y, z.
var u = fadeCurve.Calculate(rx);
var v = fadeCurve.Calculate(ry);
var w = fadeCurve.Calculate(rz);
// Hash coordinates of the 8 cube corners.
var a = permutation[cx] + cy;
var aa = permutation[a] + cz;
var ab = permutation[a + 1] + cz;
var b = permutation[cx + 1] + cy;
var ba = permutation[b] + cz;
var bb = permutation[b + 1] + cz;
// Gradients of the 8 cube corners.
var g0 = NoiseGradients.Calculate(permutation[aa], rx, ry, rz);
var g1 = NoiseGradients.Calculate(permutation[ba], rx - 1, ry, rz);
var g2 = NoiseGradients.Calculate(permutation[ab], rx, ry - 1, rz);
var g3 = NoiseGradients.Calculate(permutation[bb], rx - 1, ry - 1, rz);
var g4 = NoiseGradients.Calculate(permutation[aa + 1], rx, ry, rz - 1);
var g5 = NoiseGradients.Calculate(permutation[ba + 1], rx - 1, ry, rz - 1);
var g6 = NoiseGradients.Calculate(permutation[ab + 1], rx, ry - 1, rz - 1);
var g7 = NoiseGradients.Calculate(permutation[bb + 1], rx - 1, ry - 1, rz - 1);
// Lerp.
var l0 = MathHelper.Lerp(g0, g1, u);
var l1 = MathHelper.Lerp(g2, g3, u);
var l2 = MathHelper.Lerp(g4, g5, u);
var l3 = MathHelper.Lerp(g6, g7, u);
var l4 = MathHelper.Lerp(l0, l1, v);
var l5 = MathHelper.Lerp(l2, l3, v);
return(MathHelper.Lerp(l4, l5, w));
}
// I/F
public float Sample(float x, float y, float z)
{
if (!initialized)
{
Reseed();
}
const float F3 = 1.0f / 3.0f;
const float G3 = 1.0f / 6.0f;
// Noise contributions from the four corners
float n0, n1, n2, n3;
// Skew the input space to determine which simplex cell we're in
// Very nice and simple skew factor for 3D
float s = (x + y + z) * F3;
float xs = x + s;
float ys = y + s;
float zs = z + s;
int i = MathExtension.Floor(xs);
int j = MathExtension.Floor(ys);
int k = MathExtension.Floor(zs);
float t = (float)(i + j + k) * G3;
// Unskew the cell origin back to (x,y,z) space
float X0 = i - t;
float Y0 = j - t;
float Z0 = k - t;
// The x,y,z distances from the cell origin
float x0 = x - X0;
float y0 = y - Y0;
float z0 = z - Z0;
// For the 3D case, the simplex shape is a slightly irregular tetrahedron.
// Determine which simplex we are in.
// Offsets for second corner of simplex in (i,j,k) coords
int i1, j1, k1;
// Offsets for third corner of simplex in (i,j,k) coords
int i2, j2, k2;
if (x0 >= y0)
{
if (y0 >= z0)
{
// X Y Z order
i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 1; k2 = 0;
}
else if (x0 >= z0)
{
// X Z Y order
i1 = 1; j1 = 0; k1 = 0; i2 = 1; j2 = 0; k2 = 1;
}
else
{
// Z X Y order
i1 = 0; j1 = 0; k1 = 1; i2 = 1; j2 = 0; k2 = 1;
}
}
else
{
// x0 < y0
if (y0 < z0)
{
// Z Y X order
i1 = 0; j1 = 0; k1 = 1; i2 = 0; j2 = 1; k2 = 1;
}
else if (x0 < z0)
{
// Y Z X order
i1 = 0; j1 = 1; k1 = 0; i2 = 0; j2 = 1; k2 = 1;
}
else
{
// Y X Z order
i1 = 0; j1 = 1; k1 = 0; i2 = 1; j2 = 1; k2 = 0;
}
}
// A step of (1,0,0) in (i,j,k) means a step of (1-c,-c,-c) in (x,y,z),
// a step of (0,1,0) in (i,j,k) means a step of (-c,1-c,-c) in (x,y,z), and
// a step of (0,0,1) in (i,j,k) means a step of (-c,-c,1-c) in (x,y,z), where
// c = 1/6.
// Offsets for second corner in (x,y,z) coords
float x1 = x0 - i1 + G3;
float y1 = y0 - j1 + G3;
float z1 = z0 - k1 + G3;
// Offsets for third corner in (x,y,z) coords
float x2 = x0 - i2 + 2.0f * G3;
float y2 = y0 - j2 + 2.0f * G3;
float z2 = z0 - k2 + 2.0f * G3;
// Offsets for last corner in (x,y,z) coords
float x3 = x0 - 1.0f + 3.0f * G3;
float y3 = y0 - 1.0f + 3.0f * G3;
float z3 = z0 - 1.0f + 3.0f * G3;
// Wrap the integer indices at 'modMask', to avoid indexing perm[] out of bounds
int ii = i & modMask;
int jj = j & modMask;
int kk = k & modMask;
// Calculate the contribution from the four corners
float t0 = 0.6f - x0 * x0 - y0 * y0 - z0 * z0;
if (t0 < 0.0f)
{
n0 = 0.0f;
}
else
{
t0 *= t0;
n0 = t0 * t0 * NoiseGradients.Calculate(
permutation[ii + permutation[jj + permutation[kk]]], x0, y0, z0);
}
float t1 = 0.6f - x1 * x1 - y1 * y1 - z1 * z1;
if (t1 < 0.0f)
{
n1 = 0.0f;
}
else
{
t1 *= t1;
n1 = t1 * t1 * NoiseGradients.Calculate(
permutation[ii + i1 + permutation[jj + j1 + permutation[kk + k1]]], x1, y1, z1);
}
float t2 = 0.6f - x2 * x2 - y2 * y2 - z2 * z2;
if (t2 < 0.0f)
{
n2 = 0.0f;
}
else
{
t2 *= t2;
n2 = t2 * t2 * NoiseGradients.Calculate(
permutation[ii + i2 + permutation[jj + j2 + permutation[kk + k2]]], x2, y2, z2);
}
float t3 = 0.6f - x3 * x3 - y3 * y3 - z3 * z3;
if (t3 < 0.0f)
{
n3 = 0.0f;
}
else
{
t3 *= t3;
n3 = t3 * t3 * NoiseGradients.Calculate(
permutation[ii + 1 + permutation[jj + 1 + permutation[kk + 1]]], x3, y3, z3);
}
// Add contributions from each corner to get the final noise value.
// The result is scaled to stay just inside [-1,1]
return(32.0f * (n0 + n1 + n2 + n3));
}
