ru:: two new platform shapes

rogueviz/ru/classes.cpp

@@ -519,6 +519,26 @@ struct rope_platform : public moving_platform {
   void draw() override;
   };
 
+struct horoplatform : public moving_platform {
+  xy a, b;
+  ld period, shift;
+  xy location_at(ld t) override;
+  string get_shape_name() override { return a.y == b.y ? "horo" : "equi"; }
+  string get_help() override { return
+    a.y == b.y ?
+      "Go back and forth between two locations, on a horocyclic path."
+    : "Go back and forth between two locations, on an equidistant path.";
+    }
+  };
+
+struct cycloid_platform : public moving_platform {
+  moving_platform *base;
+  ld period, shift;
+  xy location_at(ld t) override;
+  string get_shape_name() override { return "cycloid"; }
+  string get_help() override { return "These go in a circle around another moving object."; }
+  };
+
 struct saw: public entity {
   unique_ptr<entity> base;
   moving_platform& mp() { return (moving_platform&)(*base); }

rogueviz/ru/entity.cpp

@@ -647,6 +647,22 @@ xy pendulum_platform::location_at(ld t) {
   return from_hyper(rgpushxto0(h1) * rspintox(gpushxto0(h1) * h2) * xpush0(x));
   }
 
+xy horoplatform::location_at(ld t) {
+  ld tp = t / game_fps / period - shift;
+  tp = tp - floor(tp);
+  tp = min(2*tp, 2-2*tp);
+  return xy(lerp(a.x, b.x, tp), lerp(a.y, b.y, tp));
+  }
+
+xy cycloid_platform::location_at(ld t) {
+  auto b =base->location_at(t);
+  auto h1 = to_hyper(b);
+  auto ph = t / game_fps / period + shift;
+  auto h2 = rgpushxto0(h1) * xspinpush0(ph * TAU, radius);
+  auto p = from_hyper(h2);
+  return p;
+  }
+
 xy ellipse_platform::location_at(ld t) {
   if(points.empty()) {
     auto h1 = to_hyper(a);

rogueviz/ru/load-world.cpp

@@ -108,6 +108,8 @@ void create_long_rope(room& r, int step, xy w) {
 
 mapswitch *lmev;
 
+moving_platform *last_platform;
+
 void load_room(fhstream& f, cell *c) {
   setdist(c, 7, nullptr);
   auto& r = *get_room_at(c);
@@ -329,11 +331,25 @@ void load_room(fhstream& f, cell *c) {
       else if(cap == "PENDULUM") {
         auto b = std::make_unique<pendulum_platform>();
         b->a = get_xy(); b->b = get_xy(); b->period = get_ld(); b->shift = get_ld();
+        last_platform = &*b;
+        r.entities.emplace_back(std::move(b));
+        }
+      else if(cap == "HORO") {
+        auto b = std::make_unique<horoplatform>();
+        b->a = get_xy(); b->b = get_xy(); b->period = get_ld(); b->shift = get_ld();
+        last_platform = &*b;
         r.entities.emplace_back(std::move(b));
         }
       else if(cap == "ELLIPSE") {
         auto b = std::make_unique<ellipse_platform>();
         b->a = get_xy(); b->b = get_xy(); b->period = get_ld(); b->shift = get_ld(); b->ratio = get_ld();
+        last_platform = &*b;
+        r.entities.emplace_back(std::move(b));
+        }
+      else if(cap == "CYCLOID") {
+        auto b = std::make_unique<cycloid_platform>();
+        b->base = last_platform; b->radius = get_ld(); b->period = get_ld(); b->shift = get_ld();
+        last_platform = &*b;
         r.entities.emplace_back(std::move(b));
         }
       else if(cap == "SAW") {