C++ Piecewise::firstValue方法代码示例

Geom::Piecewise<Geom::D2<Geom::SBasis> >
LPEOffset::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > const & pwd2_in)
{
    using namespace Geom;

    Piecewise<D2<SBasis> > output;

    double t = nearest_point(offset_pt, pwd2_in);
    Point A = pwd2_in.valueAt(t);
    double offset = L2(A - offset_pt);

    Piecewise<D2<SBasis> > der = unitVector(derivative(pwd2_in));
    Piecewise<D2<SBasis> > n   = rot90(der);

    output  = pwd2_in + n * offset;
    append_half_circle(output, pwd2_in.lastValue(), n.lastValue() * offset);
    output.continuousConcat(reverse(pwd2_in - n * offset));
    append_half_circle(output, pwd2_in.firstValue(), -n.firstValue() * offset);

    // TODO: here we should remove self-overlaps by applying the "union" boolop
    //       but we'd need to convert the path to a Shape, which is currently
    //       broken in 2geom, so we return the unaltered path

    return output;
}

    void draw(cairo_t *cr,
	      std::ostringstream *notify,
	      int width, int height, bool save, std::ostringstream *timer_stream) {
        srand(10);
        for(unsigned i=0; i<NB_SLIDER; i++){
            adjuster[i].pos[X] = 30+i*20;
            if (adjuster[i].pos[Y]<100) adjuster[i].pos[Y] = 100;
            if (adjuster[i].pos[Y]>400) adjuster[i].pos[Y] = 400;
            cairo_move_to(cr, Point(30+i*20,100));
            cairo_line_to(cr, Point(30+i*20,400));
            cairo_set_line_width (cr, .5);
            cairo_set_source_rgba (cr, 0., 0., 0., 1);
            cairo_stroke(cr);
        }
        double tol     = (400-adjuster[0].pos[Y])/300.*5+0.05;
        double tau     = (400-adjuster[1].pos[Y])/300.;
//         double scale_topback  = (250-adjuster[2].pos[Y])/150.*5;
//         double scale_botfront = (250-adjuster[3].pos[Y])/150.*5;
//         double scale_botback  = (250-adjuster[4].pos[Y])/150.*5;
//         double growth =       1+(250-adjuster[5].pos[Y])/150.*.1;
//         double rdmness =      1+(400-adjuster[6].pos[Y])/300.*.9;
//         double bend_amount    = (250-adjuster[7].pos[Y])/300.*100.;

        b1_handle.pts.back() = b2_handle.pts.front(); 
        b1_handle.pts.front() = b2_handle.pts.back(); 
        D2<SBasis> B1 = b1_handle.asBezier();
        D2<SBasis> B2 = b2_handle.asBezier();
        
        cairo_set_line_width(cr, 0.3);
        cairo_set_source_rgba(cr, 0, 0, 0, 1);
        cairo_d2_sb(cr, B1);
        cairo_d2_sb(cr, B2);
        cairo_set_line_width (cr, .5);
        cairo_set_source_rgba (cr, 0., 0., 0., 1);
        cairo_stroke(cr);

        
        Piecewise<D2<SBasis> >B;
        B.concat(Piecewise<D2<SBasis> >(B1));
        B.continuousConcat(Piecewise<D2<SBasis> >(B2));

        Piecewise<SBasis> are;
        
        Point centroid_tmp(0,0);
        are = integral(dot(B, rot90(derivative(B))))*0.5;
        are = (are - are.firstValue())*(height/10) / (are.lastValue() - are.firstValue());
    
        D2<Piecewise<SBasis> > are_graph(Piecewise<SBasis>(Linear(0, width)), are );
        std::cout << are.firstValue() << "," << are.lastValue() << std::endl;
        cairo_save(cr);
        cairo_d2_pw_sb(cr, are_graph);
        cairo_set_line_width (cr, .5);
        cairo_set_source_rgba (cr, 0., 0., 0., 1);
        cairo_stroke(cr);
        cairo_restore(cr);
        

#if 0
        std::vector<Piecewise<D2<SBasis> > >f = split_at_discontinuities(B);
        std::list<Point> p = toPoly( f, tol);
        uncross(p);
        cairo_move_to(cr, p.front());
        for (std::list<Point>::iterator pt = p.begin(); pt!=p.end(); ++pt){
            cairo_line_to(cr, *pt);
            //if (i++>p.size()*tau) break;
        } 
        cairo_set_line_width (cr, 3);
        cairo_set_source_rgba (cr, 1., 0., 0., .5);
        cairo_stroke(cr);

        if ( p.size()<3) return;
        double tot_area = 0;
        std::list<Point>::iterator a = p.begin(), b=a;
        b++;
        while(b!=p.end()){
            tot_area += ((*b)[X]-(*a)[X]) * ((*b)[Y]+(*a)[Y])/2;
            a++;b++;
        }
        bool clockwise = tot_area < 0;

        std::vector<Triangle> tri;
        int nbiter =0;
        triangulate(p,tri,clockwise);
        cairo_set_source_rgba (cr, 1., 1., 0., 1);
        cairo_stroke(cr);
        for (unsigned i=0; i<tri.size(); i++){
            cairo_move_to(cr, tri[i].a);
            cairo_line_to(cr, tri[i].b);
            cairo_line_to(cr, tri[i].c);
            cairo_line_to(cr, tri[i].a);
            cairo_set_line_width (cr, .5);
            cairo_set_source_rgba (cr, 0., 0., .9, .5);
            cairo_stroke(cr);
            cairo_move_to(cr, tri[i].a);
            cairo_line_to(cr, tri[i].b);
            cairo_line_to(cr, tri[i].c);
            cairo_line_to(cr, tri[i].a);
            cairo_set_source_rgba (cr, 0.5, 0., .9, .1);
            cairo_fill(cr);
        } 
//.........这里部分代码省略.........