Give the player first move advantage, but maybe this should be a setting on motion so that some enemies can beat the player.

systems.cpp

@@ -33,25 +33,33 @@ void System::init_positions(DinkyECS::World &world) {
   });
 }
 
+inline void move_entity(spatial_map &collider, Map &game_map, Position &position, Motion &motion, DinkyECS::Entity ent) {
+  Point move_to = {
+    position.location.x + motion.dx,
+    position.location.y + motion.dy
+  };
+  motion = {0,0}; // clear it after getting it
+
+  if(game_map.inmap(move_to.x, move_to.y) &&
+      !game_map.iswall(move_to.x, move_to.y) &&
+      !collider.occupied(move_to))
+  {
+    collider.move(position.location, move_to, ent);
+    position.location = move_to;
+  }
+}
+
 void System::motion(DinkyECS::World &world, Map &game_map) {
   auto &collider = world.get<spatial_map>();
+  auto &player = world.get<Player>();
+  auto &player_position = world.component<Position>(player.entity);
+  auto &player_motion = world.component<Motion>(player.entity);
+  move_entity(collider, game_map, player_position, player_motion, player.entity);
 
   world.system<Position, Motion>([&](const auto &ent, auto &position, auto &motion) {
     // don't process entities that don't move
     if(motion.dx != 0 || motion.dy != 0) {
-      Point move_to = {
-        position.location.x + motion.dx,
-        position.location.y + motion.dy
-      };
-      motion = {0,0}; // clear it after getting it
-
-      if(game_map.inmap(move_to.x, move_to.y) &&
-          !game_map.iswall(move_to.x, move_to.y) &&
-          !collider.occupied(move_to))
-      {
-        collider.move(position.location, move_to, ent);
-        position.location = move_to;
-      }
+      move_entity(collider, game_map, position, motion, ent);
     }
   });
 }