prefabs/slots

• C

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  #include <slots.h>
  #include <stdio.h>
   
  // Prefab hierarchies that use the non-fragmenting Parent storage automatically
  // let applications resolve an instantiated child from its prefab child. This
  // provides slot-like lookup without adding a relationship to either entity.
   
  int main(int argc, char *argv[]) {
      ecs_world_t *ecs = ecs_init_w_args(argc, argv);
   
      // Create a prefab hierarchy with non-fragmenting Parent storage.
      ecs_entity_t SpaceShip = ecs_entity(ecs, { .name = "SpaceShip" });
      ecs_add_id(ecs, SpaceShip, EcsPrefab);
          ecs_entity_t Engine = ecs_new_w_parent(ecs, SpaceShip, "Engine");
      
          ecs_entity_t Cockpit = ecs_new_w_parent(ecs, SpaceShip, "Cockpit");
   
          ecs_entity_t PilotSeat = ecs_new_w_parent(ecs, Cockpit, "PilotSeat");
   
      // Create a prefab instance.
      ecs_entity_t inst = ecs_entity(ecs, { .name = "my_spaceship" });
      ecs_add_pair(ecs, inst, EcsIsA, SpaceShip);
   
      // Get the instantiated children from their prefab children. A nested child
      // is resolved from the corresponding instance parent.
      ecs_entity_t inst_engine = ecs_get_target(ecs, inst, Engine, 0);
      ecs_entity_t inst_cockpit = ecs_get_target(ecs, inst, Cockpit, 0);
      ecs_entity_t inst_seat = ecs_get_target(ecs, inst_cockpit, PilotSeat, 0);
   
      printf("instance engine found:  %s\n", inst_engine ? "true" : "false");
      printf("instance cockpit found: %s\n", inst_cockpit ? "true" : "false");
      printf("instance seat found:    %s\n", inst_seat ? "true" : "false");
   
      // Output:
      //  instance engine found:  true
      //  instance cockpit found: true
      //  instance seat found:    true
   
      return ecs_fini(ecs);
  }

• C++

  View on GitHub

  #include <slots.h>
  #include <iostream>
   
  // Prefab hierarchies that use the non-fragmenting Parent storage automatically
  // let applications resolve an instantiated child from its prefab child. This
  // provides slot-like lookup without adding a relationship to either entity.
   
  int main() {
      flecs::world ecs;
   
      // Create a prefab hierarchy with non-fragmenting Parent storage.
      flecs::entity SpaceShip = ecs.prefab("SpaceShip");
          flecs::entity Engine = ecs.prefab(flecs::Parent{SpaceShip}, "Engine");
   
          flecs::entity Cockpit = ecs.prefab(
              flecs::Parent{SpaceShip}, "Cockpit");
   
      flecs::entity PilotSeat = ecs.prefab(
          flecs::Parent{Cockpit}, "PilotSeat");
   
      // Create a prefab instance.
      flecs::entity inst = ecs.entity("my_spaceship").is_a(SpaceShip);
   
      // Get the instantiated children from their prefab children. A nested child
      // is resolved from the corresponding instance parent.
      flecs::entity inst_engine = inst.target(Engine);
      flecs::entity inst_cockpit = inst.target(Cockpit);
      flecs::entity inst_seat = inst_cockpit.target(PilotSeat);
      
      std::cout << std::boolalpha;
      std::cout << "instance engine found:  " << inst_engine.is_valid() << "\n";
      std::cout << "instance cockpit found: " << inst_cockpit.is_valid() << "\n";
      std::cout << "instance seat found:    " << inst_seat.is_valid() << "\n";
   
      // Output:
      //  instance engine found:  true
      //  instance cockpit found: true
      //  instance seat found:    true
  }