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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-13 11:57:42 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-13 11:57:42 +0000
commit61f3ab8f23f4c924d455757bf3e65f8487521b5a (patch)
tree885599a36a308f422af98616bc733a0494fe149a /src/toys/inverse-test.cpp
parentInitial commit. (diff)
downloadlib2geom-61f3ab8f23f4c924d455757bf3e65f8487521b5a.tar.xz
lib2geom-61f3ab8f23f4c924d455757bf3e65f8487521b5a.zip
Adding upstream version 1.3.upstream/1.3upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/toys/inverse-test.cpp')
-rw-r--r--src/toys/inverse-test.cpp174
1 files changed, 174 insertions, 0 deletions
diff --git a/src/toys/inverse-test.cpp b/src/toys/inverse-test.cpp
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+#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>
+
+#include <time.h>
+using std::vector;
+using namespace Geom;
+using namespace std;
+
+static void plot(cairo_t* cr, SBasis const &B,double vscale=1,double a=0,double b=1){
+ D2<SBasis> plot;
+ plot[0]=SBasis(Linear(150+a*300,150+b*300));
+ plot[1]=B*-vscale;
+ plot[1]+=450;
+ cairo_d2_sb(cr, plot);
+ cairo_stroke(cr);
+}
+static void plot(cairo_t* cr, Piecewise<SBasis> const &f,double vscale=1){
+ for (unsigned i=0;i<f.size();i++){
+ plot(cr,f.segs[i],vscale,f.cuts[i],f.cuts[i+1]);
+ draw_cross(cr,Geom::Point(f.cuts[i]*300 + 150, f.segs[i][0][0]*(-vscale) + 450));
+ }
+}
+
+static SBasis my_inverse(SBasis f, int order){
+ double a0 = f[0][0];
+ if(a0 != 0) {
+ f -= a0;
+ }
+ double a1 = f[0][1];
+ if(a1 == 0)
+ THROW_NOTINVERTIBLE();
+ //assert(a1 != 0);// not invertible.
+ if(a1 != 1) {
+ f /= a1;
+ }
+
+ SBasis g=SBasis(order, Linear());
+ g[0] = Linear(0,1);
+ double df0=derivative(f)(0);
+ double df1=derivative(f)(1);
+ SBasis r = Linear(0,1)-g(f);
+
+ for(int i=1; i<order; i++){
+ //std::cout<<"i: "<<i<<std::endl;
+ r=Linear(0,1)-g(f);
+ //std::cout<<"t-gof="<<r<<std::endl;
+ r.normalize();
+ if (r.size()==0) return(g);
+ double a=r[i][0]/std::pow(df0,i);
+ double b=r[i][1]/std::pow(df1,i);
+ g[i] = Linear(a,b);
+ }
+
+ return(g);
+}
+
+static Piecewise<SBasis> pw_inverse(SBasis const &f, int order,double tol=.1,int depth=0){
+ SBasis g=SBasis(Linear(0,1)),r;
+ Piecewise<SBasis> res,res1,res2;
+
+ //std::cout<<"depth: "<<depth<<std::endl;
+ g=my_inverse(f,order);
+ r=g(f);
+ //std::cout<<"error: "<<g.tail_error(1)<<std::endl;
+ if (g.tailError(1)<tol){
+ res.segs.push_back(g);
+ res.cuts.push_back(f[0][0]);
+ res.cuts.push_back(f[0][1]);
+ }else if (depth<200){
+ SBasis ff;
+ ff=f(Linear(0,.5));
+ res=pw_inverse(ff,order,tol,depth+1);
+ for (unsigned i=0;i<res.size();i++){
+ res.segs[i]*=.5;
+ }
+ ff=f(Linear(.5,1));
+ res1=pw_inverse(ff,order,tol,depth+1);
+ for (unsigned i=0;i<res1.size();i++){
+ res1.segs[i]*=.5;
+ res1.segs[i]+=.5;
+ }
+ res.concat(res1);
+ }
+ return(res);
+}
+
+
+
+class InverseTester: public Toy {
+ int size;
+ PointSetHandle hand;
+
+ void draw(cairo_t *cr, std::ostringstream *notify, int width, int height, bool save, std::ostringstream *timer_stream) override {
+
+ for (int i=0;i<size;i++){
+ hand.pts[i ][0]=150+15*(i-size);
+ hand.pts[i+size][0]=450+15*(i+1);
+ cairo_move_to(cr, Geom::Point(hand.pts[i ][0],150));
+ cairo_line_to(cr, Geom::Point(hand.pts[i ][0],450));
+ cairo_move_to(cr, Geom::Point(hand.pts[i+size][0],150));
+ cairo_line_to(cr, Geom::Point(hand.pts[i+size][0],450));
+ }
+ cairo_move_to(cr, Geom::Point(0,300));
+ cairo_line_to(cr, Geom::Point(600,300));
+
+ cairo_set_line_width (cr, 1);
+ cairo_set_source_rgba (cr, 0.2, 0.2, 0.2, 1);
+ cairo_stroke(cr);
+
+ SBasis f(size, Linear());//=SBasis(Linear(0,.5));
+ for (int i=0;i<size;i++){
+ f[i] = Linear(-(hand.pts[i ][1]-300)*std::pow(4.,i)/150,
+ -(hand.pts[i+size][1]-300)*std::pow(4.,i)/150 );
+ }
+ plot(cr,Linear(0,1),300);
+
+ f.normalize();
+ cairo_set_line_width (cr, 2);
+ cairo_set_source_rgba (cr, 0., 0., 0.8, 1);
+ plot(cr,f,300);
+
+ *notify<<"Use hand.pts to set the coefficients of the (blue) s-basis."<<std::endl;
+ *notify<<" (keep it monotonic!)"<<std::endl;
+ *notify<<"red=flipped inverse; should be the same as the blue one."<<std::endl;
+
+ try {
+ Piecewise<SBasis> g=pw_inverse(f,3);
+ cairo_set_line_width (cr, 1);
+ cairo_set_source_rgba (cr, 0.8, 0., 0., 1);
+ plot(cr,g,300);
+ Piecewise<SBasis> h=compose(g,f);
+ cairo_set_line_width (cr, 1);
+ cairo_set_source_rgba (cr, 0., 0.8, 0., 1);
+ plot(cr,h,300);
+ *notify<<g.size()<<" segments.";
+ } catch(NotInvertible) {
+ *notify << "function not invertible!" << std::endl;
+ }
+
+ Toy::draw(cr, notify, width, height, save,timer_stream);
+ }
+
+public:
+ InverseTester() {
+ size=4;
+ if(hand.pts.empty()) {
+ for(int i = 0; i < 2*size; i++)
+ hand.pts.emplace_back(0,150+150+uniform()*300*0);
+ }
+ hand.pts[0][1]=300;
+ hand.pts[size][1]=150;
+ handles.push_back(&hand);
+ }
+};
+
+int main(int argc, char **argv) {
+ init(argc, argv, new InverseTester);
+ 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:encoding = utf-8:textwidth = 99 :