/// <summary>
/// Returns the noise value at the given coordinates.
/// </summary>
/// <param name="x"></param>
/// <param name="y"></param>
/// <returns></returns>
public static double ValueAt(double x, double y)
{
// separate whole and fractional components
x = SlurMath.Fract(x, out int i);
y = SlurMath.Fract(y, out int j);
// wrap to perm table
i &= 255;
j &= 255;
// calculate noise contributions from each corner
double n00 = GradDot(ToIndex(i, j), x, y);
double n10 = GradDot(ToIndex(i + 1, j), x - 1.0, y);
double n01 = GradDot(ToIndex(i, j + 1), x, y - 1.0);
double n11 = GradDot(ToIndex(i + 1, j + 1), x - 1.0, y - 1.0);
// eased values for x and y
x = SlurMath.HermiteC2(x);
y = SlurMath.HermiteC2(y);
// bilinear interpolation
return(SlurMath.Lerp(
SlurMath.Lerp(n00, n10, x),
SlurMath.Lerp(n01, n11, x),
y));
}
/// <summary>
/// Returns the noise value at the given coordinates
/// </summary>
/// <param name="x"></param>
/// <param name="y"></param>
/// <param name="z"></param>
/// <returns></returns>
public static double ValueAt(double x, double y, double z)
{
// separate whole and fractional components
x = SlurMath.Fract(x, out int i);
y = SlurMath.Fract(y, out int j);
z = SlurMath.Fract(z, out int k);
// calculate noise contributions from each corner
double n000 = GradDot(ToIndex(i, j, k), x, y, z);
double n100 = GradDot(ToIndex(i + 1, j, k), x - 1.0, y, z);
double n010 = GradDot(ToIndex(i, j + 1, k), x, y - 1.0, z);
double n110 = GradDot(ToIndex(i + 1, j + 1, k), x - 1.0, y - 1.0, z);
double n001 = GradDot(ToIndex(i, j, k + 1), x, y, z - 1.0);
double n101 = GradDot(ToIndex(i + 1, j, k + 1), x - 1.0, y, z - 1.0);
double n011 = GradDot(ToIndex(i, j + 1, k + 1), x, y - 1.0, z - 1.0);
double n111 = GradDot(ToIndex(i + 1, j + 1, k + 1), x - 1.0, y - 1.0, z - 1.0);
// eased values for each dimension
x = SlurMath.HermiteC2(x);
y = SlurMath.HermiteC2(y);
z = SlurMath.HermiteC2(z);
// trilinear interpolation
return(SlurMath.Lerp(
SlurMath.Lerp(
SlurMath.Lerp(n000, n100, x),
SlurMath.Lerp(n010, n110, x),
y),
SlurMath.Lerp(
SlurMath.Lerp(n001, n101, x),
SlurMath.Lerp(n011, n111, x),
y),
z));
}