render entities only if visible

rogueviz/ru/classes.cpp

@@ -116,6 +116,8 @@ struct entity {
   double gwhere_x, gwhere_y;
   double gvel_x, gvel_y;
 
+  bool visible(room *r);
+
   void clearg() {
     gwhere_x = where_x;
     gwhere_y = where_y;

rogueviz/ru/entity.cpp

@@ -16,6 +16,12 @@ bbox entity::get_pixel_bbox_at(double x, double y) {
   return b;
   }
 
+bool entity::visible(room *r) {
+  auto bb = get_intersect(pixel_to_block(get_pixel_bbox()), room_bb);
+  for(int y = bb.miny; y < bb.maxy; y++) for(int x = bb.minx; x < bb.maxx; x++) if(r->fov[y][x]) return true;
+  return false;
+  }
+
 void entity::apply_grav() {
 
   if(non_hyperbolic) return apply_portal_grav();

rogueviz/ru/geometry.cpp

@@ -94,8 +94,21 @@ bbox join(bbox a, bbox b) {
   return r;
   }
 
+bbox room_bb{0, 0, room_x, room_y};
+bbox screen_bb{0, 0, screen_x, screen_y};
+
+bbox get_intersect(bbox a, bbox b) {
+  bbox r;
+  r.minx = max(a.minx, b.minx);
+  r.miny = max(a.miny, b.miny);
+  r.maxx = min(a.maxx, b.maxx);
+  r.maxy = min(a.maxy, b.maxy);
+  return r;
+  }
+
 bool intersect(bbox a, bbox b) {
-  return max(a.minx, b.minx) < min(a.maxx, b.maxx) && max(a.miny, b.miny) < min(a.maxy, b.maxy);
+  auto g = get_intersect(a, b);
+  return g.minx < g.maxx && g.miny < g.maxy;
   }
 
 void print(hstream& hs, const bbox& b) {

rogueviz/ru/render.cpp

@@ -245,7 +245,9 @@ void man::draw() {
 void render_room_objects(room *r) {
   initquickqueue();
   if(r == current_room) m.draw();
-  for(auto& e: r->entities) e->draw();
+  for(auto& e: r->entities)
+    if(e->visible(r))
+      e->draw();
   quickqueue();
   }