public double getValue(double x, double y, double z) {
assert (sourceModules[0] != null);
assert (controlPointCount >= 2);
// 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 < controlPointCount; indexPos++) {
if (sourceModuleValue < controlPoints[indexPos]) break;
}
// Find the two nearest control points so that we can map their values
// onto a quadratic curve.
int index0 = Misc.ClampValue(indexPos - 1, 0, controlPointCount - 1);
int index1 = Misc.ClampValue(indexPos, 0, controlPointCount - 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];
// Compute the alpha value used for linear interpolation.
double value0 = controlPoints[index0];
double value1 = controlPoints[index1];
double alpha = (sourceModuleValue - value0) / (value1 - value0);
if (invertTerraces) {
alpha = 1.0 - alpha;
double tempValue = value0;
value0 = value1;
value1 = tempValue;
}
// Squaring the alpha produces the terrace effect.
alpha *= alpha;
// Now perform the linear interpolation given the alpha value.
return Interp.linearInterp(value0, value1, alpha);
}