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/**
* efficient and precise flattening of curves.
* incomplete rewrite (njh)
*/
#include <2geom/d2.h>
#include <2geom/sbasis.h>
#include <2geom/bezier-to-sbasis.h>
#include <toys/path-cairo.h>
#include <toys/toy-framework-2.h>
using std::vector;
using namespace Geom;
unsigned total_pieces_sub;
unsigned total_pieces_inc;
class PreciseFlat: public Toy {
PointSetHandle hand;
void draw(cairo_t *cr, std::ostringstream *notify, int width, int height, bool save, std::ostringstream *timer_stream) override {
cairo_set_line_width (cr, 0.5);
D2<SBasis> B = hand.asBezier();
D2<SBasis> dB = derivative(B);
D2<SBasis> ddB = derivative(dB);
cairo_set_source_rgb(cr, 0,0,0);
cairo_d2_sb(cr, B);
cairo_stroke(cr);
// draw the longest chord that is no worse than tol from the curve.
Geom::Point st = unit_vector(dB(0));
double s3 = fabs(dot(hand.pts[2] - hand.pts[0], rot90(st)));
SBasis inflect = dot(dB, rot90(ddB));
std::vector<double> rts = roots(inflect);
double f = 3;
for(double rt : rts) {
draw_handle(cr, B(rt));
double tp = rt;
Geom::Point st = unit_vector(dB(tp));
Geom::Point O = B(tp);
double s4 = fabs(dot(hand.pts[3] - O, rot90(st)));
double tf = pow(f/s4, 1./3);
Geom::Point t1p = B(tp + tf*(1-tp));
Geom::Point t1m = B(tp - tf*(1-tp));
cairo_move_to(cr, t1m);
cairo_line_to(cr, t1p);
cairo_stroke(cr);
//std::cout << tp << ", " << t1m << ", " << t1p << std::endl;
}
cairo_move_to(cr, B(0));
double t0 = 2*sqrt(f/(3*s3));
//std::cout << t0 << std::endl;
cairo_line_to(cr, B(t0));
cairo_stroke(cr);
Toy::draw(cr, notify, width, height, save,timer_stream);
}
public:
PreciseFlat () {
for(unsigned i = 0; i < 4; i++)
hand.pts.emplace_back(uniform()*400, uniform()*400);
handles.push_back(&hand);
}
};
int main(int argc, char **argv) {
init(argc, argv, new PreciseFlat());
return 0;
}
/*
Local Variables:
mode:c++
c-file-style:"stroustrup"
c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
indent-tabs-mode:nil
fill-column:99
End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :
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