Properly link flecs library

engine/libs/flecs/examples/c/prefabs/slots/include/slots.h

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+#ifndef SLOTS_H
+#define SLOTS_H
+
+/* This generated file contains includes for project dependencies */
+#include "slots/bake_config.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+

engine/libs/flecs/examples/c/prefabs/slots/include/slots/bake_config.h

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+/*
+                                   )
+                                  (.)
+                                  .|.
+                                  | |
+                              _.--| |--._
+                           .-';  ;`-'& ; `&.
+                          \   &  ;    &   &_/
+                           |"""---...---"""|
+                           \ | | | | | | | /
+                            `---.|.|.|.---'
+
+ * This file is generated by bake.lang.c for your convenience. Headers of
+ * dependencies will automatically show up in this file. Include bake_config.h
+ * in your main project file. Do not edit! */
+
+#ifndef SLOTS_BAKE_CONFIG_H
+#define SLOTS_BAKE_CONFIG_H
+
+/* Headers of public dependencies */
+#include <flecs.h>
+
+#endif
+

engine/libs/flecs/examples/c/prefabs/slots/project.json

@@ -0,0 +1,10 @@
+{
+    "id": "slots",
+    "type": "application",
+    "value": {
+        "use": [
+            "flecs"
+        ],
+        "public": false
+    }
+}

engine/libs/flecs/examples/c/prefabs/slots/src/main.c

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+#include <slots.h>
+#include <stdio.h>
+
+// Slots can be combined with prefab hierarchies to make it easier to access
+// the child entities created for an instance.
+//
+// To create a slot, the SlotOf relationship is added to the child of a prefab,
+// with as relationship target the prefab for which to register the slot. When
+// the prefab is instantiated, each slot will be added as a relationship pair
+// to the instance that looks like this:
+//   (PrefabChild, InstanceChild)
+//
+// For a SpaceShip prefab and an Engine child, that pair would look like this:
+//   (SpaceShip.Engine, Instance.Engine)
+//
+// To get the entity for a slot, an application can use the regular functions
+// to inspect relationships and relationship targets (see code).
+//
+// Slots can be added to any level of a prefab hierarchy, as long as it is above
+// (a parent of) the slot itself. When the prefab tree is instantiated, the 
+// slots are added to the entities that correspond with the prefab children.
+//
+// Without slots, an application would have to rely on manually looking up 
+// entities by name to get access to the instantiated children, like what the
+// hierarchy example does.
+
+int main(int argc, char *argv[]) {
+    ecs_world_t *ecs = ecs_init_w_args(argc, argv);
+
+    // Create the same prefab hierarchy as from the hierarchy example, but now
+    // with the SlotOf relationship.
+    ecs_entity_t SpaceShip = ecs_new_prefab(ecs, "SpaceShip");
+        ecs_entity_t Engine = ecs_new_prefab(ecs, "Engine");
+        ecs_add_pair(ecs, Engine, EcsChildOf, SpaceShip);
+        ecs_add_pair(ecs, Engine, EcsSlotOf, SpaceShip);
+    
+        ecs_entity_t Cockpit = ecs_new_prefab(ecs, "Cockpit");
+        ecs_add_pair(ecs, Cockpit, EcsChildOf, SpaceShip);
+        ecs_add_pair(ecs, Cockpit, EcsSlotOf, SpaceShip);
+
+        // Add an additional child to the Cockpit prefab to demonstrate how 
+        // slots can be different from the parent. This slot could have been
+        // added to the Cockpit prefab, but instead we register it on the top
+        // level SpaceShip prefab.
+        ecs_entity_t PilotSeat = ecs_new_prefab(ecs, "PilotSeat");
+        ecs_add_pair(ecs, PilotSeat, EcsChildOf, Cockpit);
+        ecs_add_pair(ecs, PilotSeat, EcsSlotOf, SpaceShip);
+
+    // Create a prefab instance.
+    ecs_entity_t inst = ecs_new_entity(ecs, "my_spaceship");
+    ecs_add_pair(ecs, inst, EcsIsA, SpaceShip);
+
+    // Get the instantiated entities for the prefab slots
+    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, PilotSeat, 0);
+
+    char *path = ecs_get_fullpath(ecs, inst_engine);
+    printf("instance engine:  %s\n", path);
+    ecs_os_free(path);
+
+    path = ecs_get_fullpath(ecs, inst_cockpit);
+    printf("instance cockpit: %s\n", path);
+    ecs_os_free(path);
+
+    path = ecs_get_fullpath(ecs, inst_seat);
+    printf("instance seat:    %s\n", path);
+    ecs_os_free(path);
+
+    // Output:
+    //  instance engine:  my_spaceship.Engine
+    //  instance cockpit: my_spaceship.Cockpit
+    //  instance seat:    my_spaceship.Cockpit.PilotSeat
+
+    return ecs_fini(ecs);
+}