src/live_effects/lpe-knot.cpp

   1 #define INKSCAPE_LPE_KNOT_CPP
   2 /** \file
   3  * LPE <knot> implementation
   4  */
   5 /*
   6  * Authors:
   7  *   JF Barraud
   8 *
   9 * Copyright (C) JF Barraud 2007 <jf.barraud@gmail.com>
  10  *
  11  * Released under GNU GPL, read the file 'COPYING' for more information
  12  */
  13
  14 #include "live_effects/lpe-knot.h"
  15
  16 #include <2geom/path.h>
  17 #include <2geom/d2.h>
  18 #include <2geom/crossing.h>
  19 #include <2geom/path-intersection.h>
  20
  21 namespace Inkscape {
  22 namespace LivePathEffect {
  23
  24 LPEKnot::LPEKnot(LivePathEffectObject *lpeobject) :
  25     Effect(lpeobject),
  26     // initialise your parameters here:
  27     interruption_width(_("Gap width"), _("The width of the gap in the path where it self-intersects"), "interruption_width", &wr, this, 10)
  28 {
  29     // register all your parameters here, so Inkscape knows which parameters this effect has:
  30     registerParameter( dynamic_cast<Parameter *>(&interruption_width) );
  31 }
  32
  33 LPEKnot::~LPEKnot()
  34 {
  35
  36 }
  37
  38 //remove an interval from an union of intervals.
  39 std::vector<Geom::Interval> complementOf(Geom::Interval I, std::vector<Geom::Interval> domain){
  40     std::vector<Geom::Interval> ret;
  41     double min = domain.front().min();
  42     double max = domain.back().max();
  43     Geom::Interval I1 = Geom::Interval(min,I.min());
  44     Geom::Interval I2 = Geom::Interval(I.max(),max);
  45
  46     for (unsigned i = 0; i<domain.size(); i++){
  47         boost::optional<Geom::Interval> I1i = intersect(domain.at(i),I1);
  48         if (I1i) ret.push_back(I1i.get());
  49         boost::optional<Geom::Interval> I2i = intersect(domain.at(i),I2);
  50         if (I2i) ret.push_back(I2i.get());
  51     }
  52     return ret;
  53 }
  54
  55 Geom::Interval
  56 findShadowedTime(Geom::Path &patha,
  57                  Geom::Path &pathb,
  58                  Geom::Crossing crossing,
  59                  unsigned idx, double width){
  60     using namespace Geom;
  61     double curveidx, timeoncurve = modf(crossing.getOtherTime(idx),&curveidx);
  62     if(curveidx == pathb.size() && timeoncurve == 0) { curveidx--; timeoncurve = 0.99999;}
  63     assert(curveidx >= 0 && curveidx < pathb.size());
  64
  65     std::vector<Point> MV = pathb[unsigned(curveidx)].pointAndDerivatives(timeoncurve,1);
  66     Point T = unit_vector(MV.at(1));
  67     Point N = T.cw();
  68     Point A = MV.at(0)-10*width*T, B = MV.at(0)+10*width*T;
  69
  70     std::vector<Geom::Path> cutter;
  71     Geom::Path cutterLeft  = Geom::Path();
  72     Geom::Path cutterRight = Geom::Path();
  73     cutterLeft.append (LineSegment (A-width*N, B-width*N));
  74     cutterRight.append(LineSegment (A+width*N, B+width*N));
  75     cutter.push_back(cutterLeft);
  76     cutter.push_back(cutterRight);
  77
  78     std::vector<Geom::Path> patha_as_vect = std::vector<Geom::Path>(1,patha);
  79
  80     CrossingSet crossingTable = crossings (patha_as_vect, cutter);
  81     double t0 = crossing.getTime(idx);
  82     double tmin = 0,tmax = patha.size()-0.0001;
  83     assert(crossingTable.size()>=1);
  84     for (unsigned c=0; c<crossingTable.front().size(); c++){
  85         double t = crossingTable.front().at(c).ta;
  86         assert(crossingTable.front().at(c).a==0);
  87         if (t>tmin and t<t0) tmin = t;
  88         if (t<tmax and t>t0) tmax = t;
  89     }
  90     //return Interval(t0-0.1,t0+0.1);
  91     return Interval(tmin,tmax);
  92 }
  93
  94 //Just a try; this should be moved to 2geom if ever it works.
  95 std::vector<Geom::Path>
  96 split_loopy_bezier (std::vector<Geom::Path> const & path_in){
  97
  98     std::vector<Geom::Path> ret;
  99     std::vector<Geom::Path>::const_iterator pi=path_in.begin();
 100     for(; pi != path_in.end(); pi++) {
 101         ret.push_back(Geom::Path());
 102         for (Geom::Path::const_iterator curve(pi->begin()),end(pi->end()); curve != end; ++curve){
 103
 104             //is the current curve a cubic bezier?
 105             if(Geom::CubicBezier const *cubic_bezier = dynamic_cast<Geom::CubicBezier const *>(&(*curve))){
 106                 Geom::CubicBezier theCurve = *cubic_bezier;
 107                 std::vector<Geom::Point> A = theCurve.points();
 108
 109                 //is there a crossing in the polygon?
 110                 if( cross(A[2]-A[0],A[1]-A[0])*cross(A[3]-A[0],A[1]-A[0])<0 &&
 111                     cross(A[0]-A[3],A[2]-A[3])*cross(A[1]-A[3],A[2]-A[3])<0){
 112
 113                     //split the curve where the tangent is parallel to the chord through end points.
 114                     double a = cross(A[3]-A[0],A[1]-A[2]);
 115                     double c = cross(A[3]-A[0],A[1]-A[0]);
 116                     double t; //where to split; solution of 3*at^2-(a+c)t +c = 0.
 117                     //TODO: don't we have a clean deg 2 equation solver?...
 118                     if (fabs(a)<.0001){
 119                         t = .5;
 120                     }else{
 121                         double delta = a*a-a*c+c*c;
 122                         t = ((a+c)-sqrt(delta))/2/a;
 123                         if ( t<0 || t>1 ) {t = ((a+c)+sqrt(delta))/2/a;}
 124                     }
 125                     //TODO: shouldn't Path have subdivide method?
 126                     std::pair<Geom::BezierCurve<3>, Geom::BezierCurve<3> > splitCurve;
 127                     splitCurve = theCurve.subdivide(t);
 128                     ret.back().append(splitCurve.first);
 129                     ret.back().append(splitCurve.second);
 130
 131                 }else{//cubic bezier but no crossing.
 132                     ret.back().append(*curve);
 133                 }
 134             }else{//not cubic bezier.
 135                 ret.back().append(*curve);
 136             }
 137         }
 138     }
 139     return ret;
 140 }
 141
 142
 143 std::vector<Geom::Path>
 144 LPEKnot::doEffect_path (std::vector<Geom::Path> const & input_path)
 145 {
 146     using namespace Geom;
 147     std::vector<Geom::Path> path_out;
 148     double width = interruption_width;
 149
 150     std::vector<Geom::Path> path_in = split_loopy_bezier(input_path);
 151
 152     CrossingSet crossingTable = crossings_among(path_in);
 153     for (unsigned i = 0; i < crossingTable.size(); i++){
 154         std::vector<Interval> dom;
 155         dom.push_back(Interval(0.,path_in.at(i).size()-0.00001));
 156         //TODO: handle closed curves...
 157         for (unsigned crs = 0; crs < crossingTable.at(i).size(); crs++){
 158             Crossing crossing = crossingTable.at(i).at(crs);
 159             unsigned j = crossing.getOther(i);
 160             //TODO: select dir according to a parameter...
 161             if ((crossing.dir and crossing.a==i) or (not crossing.dir and crossing.b==i) or (i==j)){
 162                 if (i==j and not crossing.dir) {
 163                     double temp = crossing.ta;
 164                     crossing.ta = crossing.tb;
 165                     crossing.tb = temp;
 166                     crossing.dir = not crossing.dir;
 167                 }
 168                 Interval hidden = findShadowedTime(path_in.at(i),path_in.at(j),crossing,i,width);
 169                 dom = complementOf(hidden,dom);
 170             }
 171         }
 172         for (unsigned comp = 0; comp < dom.size(); comp++){
 173             assert(dom.at(comp).min() >=0 and dom.at(comp).max() < path_in.at(i).size());
 174             path_out.push_back(path_in.at(i).portion(dom.at(comp)));
 175         }
 176     }
 177     return path_out;
 178 }
 179
 180
 181 /*
 182 Geom::Piecewise<Geom::D2<Geom::SBasis> >
 183 addLinearEnds (Geom::Piecewise<Geom::D2<Geom::SBasis> > & m){
 184     using namespace Geom;
 185     Piecewise<D2<SBasis> > output;
 186     Piecewise<D2<SBasis> > start;
 187     Piecewise<D2<SBasis> > end;
 188     double x,y,vx,vy;
 189
 190     x  = m.segs.front()[0].at0();
 191     y  = m.segs.front()[1].at0();
 192     vx = m.segs.front()[0][1][0]+Tri(m.segs.front()[0][0]);
 193     vy = m.segs.front()[1][1][0]+Tri(m.segs.front()[1][0]);
 194     start = Piecewise<D2<SBasis> >(D2<SBasis>(Linear (x-vx,x),Linear (y-vy,y)));
 195     start.offsetDomain(m.cuts.front()-1.);
 196
 197     x  = m.segs.back()[0].at1();
 198     y  = m.segs.back()[1].at1();
 199     vx = -m.segs.back()[0][1][1]+Tri(m.segs.back()[0][0]);;
 200     vy = -m.segs.back()[1][1][1]+Tri(m.segs.back()[1][0]);;
 201     end = Piecewise<D2<SBasis> >(D2<SBasis>(Linear (x,x+vx),Linear (y,y+vy)));
 202     //end.offsetDomain(m.cuts.back());
 203
 204     output = start;
 205     output.concat(m);
 206     output.concat(end);
 207     return output;
 208 }
 209
 210 Geom::Piecewise<Geom::D2<Geom::SBasis> >
 211 LPEKnot::doEffect_pwd2 (Geom::Piecewise<Geom::D2<Geom::SBasis> > & pwd2_in)
 212 {
 213     using namespace Geom;
 214
 215
 216     Piecewise<D2<SBasis> > output;
 217     Piecewise<D2<SBasis> > m = addLinearEnds(pwd2_in);
 218
 219     Piecewise<D2<SBasis> > v = derivative(pwd2_in);
 220     Piecewise<D2<SBasis> > n = unitVector(v);
 221
 222 // // -------- Pleins et delies vs courbure ou direction...
 223 //     Piecewise<D2<SBasis> > a = derivative(v);
 224 //     Piecewise<SBasis> a_cross_n = cross(a,n);
 225 //     Piecewise<SBasis> v_dot_n = dot(v,n);
 226 //     //Piecewise<D2<SBasis> > rfrac = sectionize(D2<Piecewise<SBasis> >(a_cross_n,v_dot_n));
 227 //     //Piecewise<SBasis> h = atan2(rfrac)*interruption_width;
 228 //     Piecewise<SBasis> h = reciprocal(curvature(pwd2_in))*interruption_width;
 229 //
 230 // //    Piecewise<D2<SBasis> > dir = Piecewise<D2<SBasis> >(D2<SBasis>(Linear(0),Linear(-1)));
 231 // //    Piecewise<SBasis> h = dot(n,dir)+1.;
 232 // //    h *= h*(interruption_width/4.);
 233 //
 234 //     n = rot90(n);
 235 //     output = pwd2_in+h*n;
 236 //     output.concat(pwd2_in-h*n);
 237 //
 238 // //-----------
 239
 240     //output.concat(m);
 241     return output;
 242 }
 243 */
 244
 245 /* ######################## */
 246
 247 } //namespace LivePathEffect (setq default-directory "c:/Documents And Settings/jf/Mes Documents/InkscapeSVN")
 248 } /* namespace Inkscape */
 249
 250 /*
 251   Local Variables:
 252   mode:c++
 253   c-file-style:"stroustrup"
 254   c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
 255   indent-tabs-mode:nil
 256   fill-column:99
 257   End:
 258 */
 259 // vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :