pointFromProportion method
Implementation
@override
Vector3 pointFromProportion(double alpha) {
var numCurves = getNumCurves();
var nRes = integerInterpolate(0, numCurves, alpha);
var n = nRes.item1;
var residue = nRes.item2;
var curve = getNthCurveFunction(n);
return curve(residue);
}