1 files changed, 125 insertions, 0 deletions
diff --git a/src/toys/sb1d.cpp b/src/toys/sb1d.cpp
new file mode 100644
index 0000000..dabbebb
--- /dev/null
+++ b/src/toys/sb1d.cpp
@@ -0,0 +1,125 @@
+#include <2geom/d2.h>
+#include <2geom/sbasis.h>
+#include <2geom/sbasis-2d.h>
+#include <2geom/bezier-to-sbasis.h>
+#include <2geom/choose.h>
+#include <2geom/convex-hull.h>
+
+#include <2geom/path.h>
+
+#include <toys/path-cairo.h>
+#include <toys/toy-framework-2.h>
+
+#include <vector>
+using std::vector;
+using namespace Geom;
+
+extern unsigned total_steps, total_subs;
+
+double& handle_to_sb(unsigned i, unsigned n, SBasis &sb) {
+    assert(i < n);
+    assert(n <= sb.size()*2);
+    unsigned k = i;
+    if(k >= n/2) {
+        k = n - k - 1;
+        return sb[k][1];
+    } else
+        return sb[k][0];
+}
+
+double handle_to_sb_t(unsigned i, unsigned n) {
+    double k = i;
+    if(i >= n/2)
+        k = n - k - 1;
+    double t = k/(2*k+1);
+    if(i >= n/2)
+        return 1 - t;
+    else
+        return t;
+}
+
+class Sb1d: public Toy {
+public:
+    PointSetHandle hand;
+    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., 0.5, 0, 1);
+        cairo_set_line_width (cr, 1);
+        
+        if(!save) {
+            for(unsigned i = 0; i < hand.pts.size(); i++) {
+                hand.pts[i][0] = width*handle_to_sb_t(i, hand.pts.size())/2 + width/4;
+                if(i)
+                    cairo_line_to(cr, hand.pts[i]);
+                else
+                    cairo_move_to(cr, hand.pts[i]);
+            }
+        }
+        
+        D2<SBasis> B;
+        B[0] = Linear(width/4, 3*width/4);
+        B[1].resize(hand.pts.size()/2);
+        for(auto & i : B) {
+            i = Linear(0);
+        }
+        for(unsigned i = 0; i < hand.pts.size(); i++) {
+            handle_to_sb(i, hand.pts.size(), B[1]) = 3*width/4 - hand.pts[i][1];
+        }
+        for(unsigned i = 1; i < B[1].size(); i++) {
+            B[1][i] = B[1][i]*choose<double>(2*i+1, i);
+        }
+        
+        Interval bs = *bounds_fast(B[1]);
+        double lo, hi;
+        lo = 3*width/4 - bs.min();
+        hi = 3*width/4 - bs.max();
+        cairo_move_to(cr, B[0](0), lo);
+        cairo_line_to(cr, B[0](1), lo);
+        cairo_move_to(cr, B[0](0), hi);
+        cairo_line_to(cr, B[0](1), hi);
+        cairo_stroke(cr);
+        *notify << "sb bounds = "<<lo << ", " <<hi<<std::endl;
+        //B[1] = SBasis(Linear(3*width/4)) - B[1];
+        *notify << B[0] << ", "; 
+        *notify << B[1];
+        Geom::Path pb;
+        B[1] = SBasis(Linear(3*width/4)) - B[1];
+        pb.append(B);
+        pb.close(false);
+        cairo_path(cr, pb);
+    
+        cairo_set_source_rgba (cr, 0., 0.125, 0, 1);
+        cairo_stroke(cr);
+    
+        Geom::ConvexHull ch(hand.pts);
+    
+        cairo_move_to(cr, ch.back());
+        for(auto i : ch) {
+            cairo_line_to(cr, i);
+        }
+        Toy::draw(cr, notify, width, height, save,timer_stream);
+    }
+public:
+Sb1d () {
+    hand.pts.emplace_back(0,450);
+    for(unsigned i = 0; i < 4; i++)
+        hand.pts.emplace_back(uniform()*400, uniform()*400);
+    hand.pts.emplace_back(0,450);
+    handles.push_back(&hand);
+}
+};
+
+int main(int argc, char **argv) {
+    init(argc, argv, new Sb1d());
+    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=4:softtabstop=4:fileencoding=utf-8:textwidth=99 :