/// <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 sourceValue = this.SourceModules[0].GetValue(x, y, z);
// Find the first element in the control point array that has an input value
// larger than the output value from the source module.
int indexPos;
for (indexPos = 0; indexPos < this.controlPoints.Count; indexPos++)
{
if (sourceValue < this.controlPoints[indexPos].InputValue)
{
break;
}
}
// Find the four nearest control points so that we can perform cubic
// interpolation.
int index0 = NoiseMath.Clamp(indexPos - 2, 0, this.controlPoints.Count - 1);
int index1 = NoiseMath.Clamp(indexPos - 1, 0, this.controlPoints.Count - 1);
int index2 = NoiseMath.Clamp(indexPos, 0, this.controlPoints.Count - 1);
int index3 = NoiseMath.Clamp(indexPos + 1, 0, this.controlPoints.Count - 1);
// If some control points are missing (which occurs if the value from the
// source module is greater than the largest input value or less than the
// smallest input value of the control point array), get the corresponding
// output value of the nearest control point and exit now.
if (index1 == index2)
{
return(this.controlPoints[index1].OutputValue);
}
// Compute the alpha value used for cubic interpolation.
double input0 = this.controlPoints[index1].InputValue;
double input1 = this.controlPoints[index2].InputValue;
double alpha = (sourceValue - input0) / (input1 - input0);
// Now perform the cubic interpolation given the alpha value.
return(NoiseMath.Cubic(
this.controlPoints[index0].OutputValue,
this.controlPoints[index1].OutputValue,
this.controlPoints[index2].OutputValue,
this.controlPoints[index3].OutputValue,
alpha));
}
