1 files changed, 96 insertions, 0 deletions
diff --git a/src/toys/conic-3.cpp b/src/toys/conic-3.cpp
new file mode 100644
index 0000000..64b2c27
--- /dev/null
+++ b/src/toys/conic-3.cpp
@@ -0,0 +1,96 @@
+/**
+ * elliptics via C-curves. (njh)
+ * Limited to 180 degrees (by end point and tangent matching criteria)
+ * Also represents cycloids
+ */
+
+#include <2geom/d2.h>
+#include <2geom/sbasis.h>
+#include <2geom/bezier-to-sbasis.h>
+#include <2geom/sbasis-to-bezier.h>
+#include <2geom/sbasis-math.h>
+
+#include <toys/path-cairo.h>
+#include <toys/toy-framework-2.h>
+
+using std::vector;
+using namespace Geom;
+
+Linear z0(0.5,1.);
+
+unsigned total_pieces;
+
+double sinC(double t) { return t - sin(t);}
+double cosC(double t) { return 1 - cos(t);}
+double tanC(double t) { return sinC(t) / cosC(t);}
+
+class Conic3: public Toy {
+    PointSetHandle psh;
+    public:
+    Conic3 () {
+        psh.push_back(100, 500);
+        psh.push_back(100, 500 - 200*M_PI/2);
+        psh.push_back(500, 500 - 200*M_PI/2);
+        psh.push_back(500, 500);
+        handles.push_back(&psh);
+    }
+
+    void draw(cairo_t *cr, std::ostringstream *notify, int width, int height, bool save, std::ostringstream *timer_stream) override {
+        cairo_set_source_rgba (cr, 0., 0., 0, 0.8);
+        cairo_set_line_width (cr, 0.5);
+        cairo_stroke(cr);
+        
+        Geom::Point a[2] = {psh.pts[0] - psh.pts[1],
+                        psh.pts[2] - psh.pts[1]};
+        double angle = Geom::angle_between(a[0], a[1]);
+        double len = std::max(Geom::L2(a[0]),
+                                Geom::L2(a[1]));
+        for(auto & i : a) 
+        i = len*unit_vector(i);
+        *notify << "angle = " << angle;
+        *notify << " sinC = " << sinC(angle);
+        *notify << " cosC = " << cosC(angle);
+        *notify << " tanC = " << tanC(angle);
+        vector<Geom::Point> e_a_h = psh.pts;
+        
+        double alpha = M_PI;
+        Piecewise<SBasis> pw(Linear(0, alpha));
+        Piecewise<SBasis> C = cos(pw);
+        Piecewise<SBasis> S = sin(pw);
+        Piecewise<SBasis> sinC = pw - S;
+        Piecewise<SBasis> cosC = Piecewise<SBasis>(1) - C;
+        Piecewise<SBasis> Z3 = sinC/sinC(1);
+        Piecewise<SBasis> Z0 = reverse(Z3);
+        Piecewise<SBasis> Z2 = cosC/cosC(1) - Z3;
+        Piecewise<SBasis> Z1 = reverse(Z2);
+        
+        Piecewise<SBasis> Z[4] = {Z0, Z1, Z2, Z3};
+        
+        D2<Piecewise<SBasis> > B;
+        for(unsigned dim  = 0; dim < 2; dim++) {
+            B[dim] = Piecewise<SBasis>(0);
+            for(unsigned i  = 0; i < 4; i++) {
+                B[dim] += Z[i]*e_a_h[i][dim];
+            }
+        }
+        cairo_d2_pw_sb(cr, B);
+        Toy::draw(cr, notify, width, height, save,timer_stream);
+    }
+};
+
+int main(int argc, char **argv) {
+    init(argc, argv, new Conic3());
+
+    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 :