Properly link flecs library

engine/libs/flecs/examples/c/entities/iterate_components/src/main.c

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+#include <iterate_components.h>
+#include <stdio.h>
+
+typedef struct {
+    double x, y;
+} Position, Velocity;
+
+void iterate_components(ecs_world_t *ecs, ecs_entity_t e) {
+    // First get the entity's type, which is a vector of (component) ids.
+    const ecs_type_t *type = ecs_get_type(ecs, e);
+
+    // 1. The easiest way to print the components is to use ecs_type_str
+    char *type_str = ecs_type_str(ecs, type);
+    printf("ecs_type_str: %s\n\n", type_str);
+    ecs_os_free(type_str);
+
+    // 2. To print individual ids, iterate the type array with ecs_id_str
+    const ecs_id_t *type_ids = type->array;
+    int32_t i, count = type->count;
+
+    for (i = 0; i < count; i ++) {
+        ecs_id_t id = type_ids[i];
+        char *id_str = ecs_id_str(ecs, id);
+        printf("%d: %s\n", i, id_str);
+        ecs_os_free(id_str);
+    }
+
+    printf("\n");
+
+    // 3. we can also inspect and print the ids in our own way. This is a
+    // bit more complicated as we need to handle the edge cases of what can be
+    // encoded in an id, but provides the most flexibility.
+    for (i = 0; i < count; i ++) {
+        ecs_id_t id = type_ids[i];
+
+        printf("%d: ", i);
+
+        if (ECS_HAS_ID_FLAG(id, PAIR)) { // See relationships
+            ecs_entity_t rel = ecs_pair_first(ecs, id);
+            ecs_entity_t tgt = ecs_pair_second(ecs, id);
+            printf("rel: %s, tgt: %s",
+                ecs_get_name(ecs, rel), ecs_get_name(ecs, tgt));
+        } else {
+            ecs_entity_t comp = id & ECS_COMPONENT_MASK;
+            printf("entity: %s", ecs_get_name(ecs, comp));
+        }
+
+        printf("\n");
+    }
+
+    printf("\n\n");
+}
+
+int main(int argc, char *argv[]) {
+    ecs_world_t *ecs = ecs_init_w_args(argc, argv);
+
+    // Ordinary components
+    ECS_COMPONENT(ecs, Position);
+    ECS_COMPONENT(ecs, Velocity);
+
+    // A tag
+    ECS_TAG(ecs, Human);
+
+    // Two tags used to create a pair
+    ECS_TAG(ecs, Eats);
+    ECS_TAG(ecs, Apples);
+
+    // Create an entity which all of the above
+    ecs_entity_t Bob = ecs_new_id(ecs);
+
+    ecs_set(ecs, Bob, Position, {10, 20});
+    ecs_set(ecs, Bob, Velocity, {1, 1});
+    ecs_add(ecs, Bob, Human);
+    ecs_add_pair(ecs, Bob, Eats, Apples);
+
+    // Iterate & components of Bob
+    printf("Bob's components:\n");
+    iterate_components(ecs, Bob);
+
+    // We can use the same function to iterate the components of a component
+    printf("Position's components:\n");
+    iterate_components(ecs, ecs_id(Position));
+
+    return ecs_fini(ecs);
+}
+
+// Output:
+
+// Bob's components:
+// ecs_type_str: Position,Velocity,Human,(Eats,Apples)
+
+// 0: Position
+// 1: Velocity
+// 2: Human
+// 3: (Eats,Apples)
+
+// 0: entity: Position
+// 1: entity: Velocity
+// 2: entity: Human
+// 3: rel: Eats, tgt: Eats
+
+
+// Position's components:
+// ecs_type_str: EcsComponent,(Identifier,Name),(Identifier,Symbol),(OnDelete,Panic)
+
+// 0: Component
+// 1: (Identifier,Name)
+// 2: (Identifier,Symbol)
+// 3: (OnDelete,Panic)
+
+// 0: entity: Component
+// 1: rel: Identifier, tgt: Identifier
+// 2: rel: Identifier, tgt: Identifier
+// 3: rel: OnDelete, tgt: OnDelete