1 files changed, 138 insertions, 0 deletions
diff --git a/src/toys/worms.cpp b/src/toys/worms.cpp
new file mode 100644
index 0000000..81e7558
--- /dev/null
+++ b/src/toys/worms.cpp
@@ -0,0 +1,138 @@
+#include <2geom/d2.h>
+#include <2geom/sbasis.h>
+#include <2geom/sbasis-geometric.h>
+#include <2geom/svg-path-parser.h>
+#include <2geom/sbasis-math.h>
+
+#include <toys/path-cairo.h>
+#include <toys/toy-framework-2.h>
+
+//Random walkers toy, written by mgsloan, initially for a school video proj.
+
+using namespace Geom;
+
+static void dot_plot(cairo_t *cr, Piecewise<D2<SBasis> > const &M, double min, double max, double space=10){
+    for( double t = min; t < max; t += space) {
+        Point pos = M(t), perp = M.valueAndDerivatives(t, 2)[1].cw() * 3;
+        draw_line_seg(cr, pos + perp, pos - perp);
+    }
+    cairo_stroke(cr);
+}
+
+D2<SBasis> random_d2() {
+    D2<SBasis> ret(SBasis(6, Linear()),
+                   SBasis(6, Linear()));
+    ret[0][0] = Linear(uniform()*720, uniform()*720);
+    ret[1][0] = Linear(uniform()*480, uniform()*480);
+    
+    int mul = 1;
+    for(int i = 1; i < 6; i++) {
+        ret[0][i] = Linear(uniform()*2000*mul - 1000, uniform()*2000*mul - 1000);
+        ret[1][i] = Linear(uniform()*2000*mul - 1000, uniform()*2000*mul - 1000);
+        mul*=2;
+    }
+    return ret;
+}
+
+class Worm {
+    Piecewise<D2<SBasis> > path;
+    int spawn_time, last_time;
+    double red, green, blue, length;
+  public:
+    void tele(int t) {
+        Piecewise<D2<SBasis> > new_path(portion(path, 0, t - last_time));
+        new_path.push(random_d2(), path.domain().max()+1);
+        path = arc_length_parametrization(new_path);
+    }
+    void add_section(const D2<SBasis> x) {
+        Piecewise<D2<SBasis> > new_path(path);
+        D2<SBasis> seg(x);
+        seg[0][0][0] = path.segs.back()[0][0][1];
+        seg[1][0][0] = path.segs.back()[1][0][1];
+        new_path.push(seg, path.domain().max()+1);
+        path = arc_length_parametrization(new_path);
+    }
+    Worm (int t, double r, double g, double b, double l) : spawn_time(t), last_time(t), red(r), green(g), blue(b), length(l) {
+        path = Piecewise<D2<SBasis> >(random_d2());
+        add_section(random_d2());
+    }
+    void draw(cairo_t *cr, int t) {
+        if(t - last_time > path.domain().max()) add_section(random_d2());
+        if(t - last_time - length > path.cuts[1]) {
+            Piecewise<D2<SBasis> > new_path;
+            new_path.push_cut(0);
+            for(unsigned i = 1; i < path.size(); i++) {
+                new_path.push(path[i], path.cuts[i+1] - path.cuts[1]);
+            }
+            last_time = t - length;
+            path = new_path;
+        }
+        cairo_set_source_rgb(cr, red, green, blue);
+        Piecewise<D2<SBasis> > port = portion(path, std::max(t - last_time - length, 0.), t - last_time);
+        cairo_pw_d2_sb(cr, port);
+        cairo_stroke(cr);
+        
+        double d = 4;
+        cairo_set_dash(cr, &d, 1, 0);
+        for(unsigned i = 1; i < path.size(); i++) {
+            if(path[i].at0() != path[i-1].at1()) {
+                draw_line_seg(cr, path[i].at0(), path[i-1].at1());
+            }
+        }
+        cairo_stroke(cr);
+        cairo_set_dash(cr, &d, 0, 0);
+        
+        cairo_set_source_rgb(cr, 0., 0., 1.);
+        dot_plot(cr, path, std::max(t - last_time - length, 0.), t - last_time);
+    }
+    void reverse_direction(int t) {
+        path = portion(path, 0, t - last_time);
+        D2<SBasis> seg = random_d2(), last = path[path.size()-1];
+        for(unsigned c = 0; c < 2; c++)
+            for(unsigned d = 1; d < seg[c].size() && d < last[c].size(); d++)
+                seg[c][d][0] = -last[c][d][1];
+        add_section(seg);
+    }
+};
+
+class Intro: public Toy {
+    int t;
+    vector<Worm> worms;
+    void draw(cairo_t *cr, std::ostringstream *notify, int width, int height, bool save, std::ostringstream *timer_stream) override {
+        t++;
+        if(t < 40 && t % 2 == 0) {
+            worms.emplace_back(t, uniform(), uniform(), uniform(), uniform() * 200 + 50);
+        }
+
+        for(auto & worm : worms) {
+            worm.draw(cr, t);
+            if(uniform() > .999) worm.tele(t);
+        }
+        
+        Toy::draw(cr, notify, width, height, save,timer_stream);
+        redraw();
+    }
+
+    int should_draw_bounds() override { return 0; }
+    
+    public:
+    Intro () {
+        t = 0;
+    }
+};
+
+int main(int argc, char **argv) {
+    init(argc, argv, new Intro(), 720, 480);
+    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 :