/** Make a path from a d2 sbasis.
\param p the d2 Symmetric basis polynomial
\returns a Path
If only_cubicbeziers is true, the resulting path may only contain CubicBezier curves.
TODO: some of this logic should be lifted into svg-path
*/
std::vector<Geom::Path>
path_from_piecewise(Geom::Piecewise<Geom::D2<Geom::SBasis> > const &B, double tol, bool only_cubicbeziers) {
Geom::PathBuilder pb;
if(B.size() == 0) return pb.peek();
Geom::Point start = B[0].at0();
pb.moveTo(start);
for(unsigned i = 0; ; i++) {
if ( (i+1 == B.size())
|| !are_near(B[i+1].at0(), B[i].at1(), tol) )
{
//start of a new path
if (are_near(start, B[i].at1()) && sbasis_size(B[i]) <= 1) {
pb.closePath();
//last line seg already there (because of .closePath())
goto no_add;
}
build_from_sbasis(pb, B[i], tol, only_cubicbeziers);
if (are_near(start, B[i].at1())) {
//it's closed, the last closing segment was not a straight line so it needed to be added, but still make it closed here with degenerate straight line.
pb.closePath();
}
no_add:
if (i+1 >= B.size()) {
break;
}
start = B[i+1].at0();
pb.moveTo(start);
} else {
build_from_sbasis(pb, B[i], tol, only_cubicbeziers);
}
}
pb.flush();
return pb.peek();
}
/** Make a path from a d2 sbasis.
\param p the d2 Symmetric basis polynomial
\returns a Path
If only_cubicbeziers is true, the resulting path may only contain CubicBezier curves.
*/
void build_from_sbasis(Geom::PathBuilder &pb, D2<SBasis> const &B, double tol, bool only_cubicbeziers) {
if (!B.isFinite()) {
THROW_EXCEPTION("assertion failed: B.isFinite()");
}
if(tail_error(B, 2) < tol || sbasis_size(B) == 2) { // nearly cubic enough
if( !only_cubicbeziers && (sbasis_size(B) <= 1) ) {
pb.lineTo(B.at1());
} else {
std::vector<Geom::Point> bez;
sbasis_to_bezier(bez, B, 4);
pb.curveTo(bez[1], bez[2], bez[3]);
}
} else {
build_from_sbasis(pb, compose(B, Linear(0, 0.5)), tol, only_cubicbeziers);
build_from_sbasis(pb, compose(B, Linear(0.5, 1)), tol, only_cubicbeziers);
}
}
