relationships/symmetric_relations

• C

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  #include <symmetric_relations.h>
  #include <stdio.h>
   
  int main(int argc, char *argv[]) {
      ecs_world_t *ecs = ecs_init_w_args(argc, argv);
   
      ECS_TAG(ecs, TradesWith);
   
      // Register TradesWith as symmetric relationship. Symmetric relationships
      // go both ways, adding (R, B) to A will also add (R, A) to B.
      ecs_add_id(ecs, TradesWith, EcsSymmetric);
   
      // Create two players
      ecs_entity_t player_1 = ecs_new(ecs);
      ecs_entity_t player_2 = ecs_new(ecs);
   
      // Add (TradesWith, player_2) to player_1. This also adds 
      // (TradesWith, player_1) to player_2.
      ecs_add_pair(ecs, player_1, TradesWith, player_2);
   
      // Log platoon of unit
      printf("Player 1 trades with Player 2: %s\n",
          (ecs_has_pair(ecs, player_1, TradesWith, player_2) ? "true" : "false"));
      printf("Player 2 trades with Player 1: %s\n",
          (ecs_has_pair(ecs, player_2, TradesWith, player_1) ? "true" : "false"));
   
      // Output:
      //  Player 1 trades with Player 2: true
      //  Player 2 trades with Player 1: true
   
      return ecs_fini(ecs);
  }

• C++

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  #include <symmetric_relations.h>
  #include <iostream>
   
  // Type for TradesWith relationship
  struct TradesWith { };
   
  int main(int, char*[]) {
      flecs::world ecs;
   
      // Register TradesWith as symmetric relationship. Symmetric relationships
      // go both ways, adding (R, B) to A will also add (R, A) to B.
      ecs.component<TradesWith>()
          .add(flecs::Symmetric);
   
      // Create two players
      flecs::entity player_1 = ecs.entity();
      flecs::entity player_2 = ecs.entity();
   
      // Add (TradesWith, player_2) to player_1. This also adds 
      // (TradesWith, player_1) to player_2.
      player_1.add<TradesWith>(player_2);
   
      // Log platoon of unit
      std::cout << "Player 1 trades with Player 2: " << 
          (player_1.has<TradesWith>(player_2) ? "true" : "false") << "\n";
      std::cout << "Player 2 trades with Player 1: " << 
          (player_2.has<TradesWith>(player_1) ? "true" : "false") << "\n";
   
      // Output:
      //  Player 1 trades with Player 2: true
      //  Player 2 trades with Player 1: true
  }