std::vector<::Movement::Spline::SplinePoint> MoveSpline::GetMidPoints()
{
std::vector<::Movement::Spline::SplinePoint> returnSpline;
if (m_splinePoints.size() > 2)
{
for (uint32_t i = 1; i < m_splinePoints.size() - 1; ++i)
{
auto splineCopy = SplinePoint(m_splinePoints[i]);
returnSpline.push_back(splineCopy);
}
}
return returnSpline;
}
SplinePoint SplinePoint::sampleBSpline(vector<SplinePoint*>& cps, double t, bool closed, int degree)
{
if (cps.empty()) {
UCBPrint("sampleBSpline", "need at least one control point");
return SplinePoint();
}
// get into 0,1 range
if (t > 1.0 || t < 0.0)
t = fmod(t, 1.0);
if (t < 0.0)
t += 1.0;
// adjust degree down as needed to get a curve, if too few control points and not on closed loop
int numCPs = int(closed ? cps.size() + degree : cps.size());
if (degree >= numCPs)
degree = numCPs - 1;
// rescale t to minSupport,maxSupport range
double minSupport = degree;
double maxSupport = numCPs;
t = (1-t)*minSupport + t*maxSupport;
// 'recursive' form of b-spline is done iteratively here
SplinePoint *bases = new SplinePoint[degree+1];
int k = (int)t;
for (int i = 0; i <= degree; ++i) {
bases[i] = *cps[(k - degree + i) % cps.size()];
}
for (int power = 1; power <= degree; ++power) {
for (int i = 0; i <= degree - power; ++i) {
int knot = k - degree + power + i;
double u_i = (double)knot;
double u_ipr1 = double(knot + degree - power + 1);
double a = (t - u_i) / (u_ipr1 - u_i);
bases[i] = SplinePoint::lerp(a, bases[i], bases[i+1]);
}
}
SplinePoint result = bases[0];
delete [] bases;
return result;
}
