/// <summary>
/// See the documentation on the base class.
/// <seealso cref="Module"/>
/// </summary>
/// <param name="x">X coordinate</param>
/// <param name="y">Y coordinate</param>
/// <param name="z">Z coordinate</param>
/// <returns>Returns the computed value</returns>
public override double GetValue(double x, double y, double z)
{
// Get the output value from the source module.
double sourceModuleValue = SourceModules[0].GetValue(x, y, z);
// Find the first element in the control point array that has a value
// larger than the output value from the source module.
int indexPos;
for (indexPos = 0; indexPos < ControlPoints.Count; indexPos++)
{
if (sourceModuleValue < ControlPoints[indexPos].x)
{
break;
}
}
// Find the two nearest control points so that we can map their values
// onto a quadratic curve.
var index0 = NoiseMath.Clamp(indexPos - 1, 0, ControlPoints.Count - 1);
var index1 = NoiseMath.Clamp(indexPos, 0, ControlPoints.Count - 1);
// If some control points are missing (which occurs if the output value from
// the source module is greater than the largest value or less than the
// smallest value of the control point array), get the value of the nearest
// control point and exit now.
if (index0 == index1)
{
return(ControlPoints[index1].x);
}
// Compute the alpha value used for linear interpolation.
var value0 = ControlPoints[index0].x;
var value1 = ControlPoints[index1].x;
var alpha = (sourceModuleValue - value0) / (value1 - value0);
if (InvertTerraces)
{
alpha = 1.0 - alpha;
NoiseMath.Swap(ref value0, ref value1);
}
// Squaring the alpha produces the terrace effect.
alpha *= alpha;
// Now perform the linear interpolation given the alpha value.
return(NoiseMath.Linear(value0, value1, alpha));
}
