Properly link flecs library

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

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+#include <basics.h>
+#include <stdio.h>
+
+// Prefabs are entities that can be used as templates for other entities. They
+// are created with a builtin Prefab tag, which by default excludes them from
+// queries and systems.
+//
+// Prefab instances are entities that have an IsA relationship to the prefab.
+// The IsA relationship causes instances to inherit the components from the 
+// prefab. By default all instances for a prefab share its components. 
+//
+// Inherited components save memory as they only need to be stored once for all
+// prefab instances. They also speed up the creation of prefabs, as inherited
+// components don't need to be copied to the instances.
+//
+// To get a private copy of a component, an instance can add it which is called 
+// an override. Overrides can be manual (by using add) or automatic (see the
+// override example).
+//
+// If a prefab has children, adding the IsA relationship instantiates the prefab
+// children for the instance (see hierarchy example).
+
+typedef struct { double value; } Defense;
+
+int main(int argc, char *argv[]) {
+    ecs_world_t *ecs = ecs_init_w_args(argc, argv);
+
+    ECS_COMPONENT(ecs, Defense);
+
+    // Create a SpaceShip prefab with a Defense component.
+    ecs_entity_t SpaceShip = ecs_new_prefab(ecs, "SpaceShip");
+    ecs_set(ecs, SpaceShip, Defense, {50});
+
+    // Create a prefab instance
+    ecs_entity_t inst = ecs_new_entity(ecs, "my_spaceship");
+    ecs_add_pair(ecs, inst, EcsIsA, SpaceShip);
+
+    // Because of the IsA relationship, the instance now shares the Defense
+    // component with the prefab, and can be retrieved as a regular component:
+    const Defense *d_inst = ecs_get(ecs, inst, Defense);
+    printf("defense: %f\n", d_inst->value);
+
+    // Because the component is shared, changing the value on the prefab will
+    // also change the value for the instance:
+    ecs_set(ecs, SpaceShip, Defense, { 100 });
+    printf("defense after set: %f\n", d_inst->value); // now prints 100
+
+    // Prefab components can be iterated like regular components:
+    ecs_query_t *q = ecs_query(ecs, {
+        .filter.terms = {
+            { .id = ecs_id(Defense) }
+        }
+    });
+
+    ecs_iter_t it = ecs_query_iter(ecs, q);
+    while (ecs_query_next(&it)) {
+        Defense *d = ecs_field(&it, Defense, 1);
+        for (int i = 0; i < it.count; i ++) {
+            printf("%s: defense: %f\n", 
+                ecs_get_name(ecs, it.entities[i]), d[i].value);
+        }
+    }
+
+    // Output:
+    //  defense: 50.000000
+    //  defense after set: 100.000000
+    //  my_spaceship: defense: 100.000000
+
+    return ecs_fini(ecs);
+}
+
+