void fnAdvectSemiLagrange_time_fraction(FluidSolver* parent, FlagGrid& flags, MACGrid& vel, GridType& orig, int order, Real strength, Real time_fraction) {
typedef typename GridType::BASETYPE T;
Real dt = (time_fraction) * parent->getDt();
std::cout << " time_fraction = " << time_fraction << std::endl ;
std::cout << " dt = " << dt << std::endl ;
bool levelset = orig.getType() & GridBase::TypeLevelset;
// forward step
GridType fwd(parent);
SemiLagrange<T> (flags, vel, fwd, orig, dt, levelset);
if (order == 1) {
orig.swap(fwd);
}
else if (order == 2) { // MacCormack
GridType bwd(parent);
GridType newGrid(parent);
// bwd <- backwards step
SemiLagrange<T> (flags, vel, bwd, fwd, -dt, levelset);
// newGrid <- compute correction
MacCormackCorrect<T> (flags, newGrid, orig, fwd, bwd, strength, levelset);
// clamp values
MacCormackClamp<T> (flags, vel, newGrid, orig, fwd, dt);
orig.swap(newGrid);
}
}
