#include #include // Queries can have wildcard terms that can match multiple instances of a // relationship or relationship target. typedef struct { int amount; } Eats; int main(int argc, char *argv[]) { ecs_world_t *ecs = ecs_init_w_args(argc, argv); ECS_COMPONENT(ecs, Eats); ECS_TAG(ecs, Apples); ECS_TAG(ecs, Pears); // Create a query that matches edible components ecs_query_t *q = ecs_query(ecs, { .filter.terms = {{ .id = ecs_pair(ecs_id(Eats), EcsWildcard ) }} }); // Create a few entities that match the query ecs_entity_t bob = ecs_new_entity(ecs, "Bob"); ecs_set_pair(ecs, bob, Eats, Apples, {10}); ecs_set_pair(ecs, bob, Eats, Pears, {5}); ecs_entity_t alice = ecs_new_entity(ecs, "Alice"); ecs_set_pair(ecs, alice, Eats, Apples, {4}); // Iterate the query ecs_iter_t it = ecs_query_iter(ecs, q); while (ecs_query_next(&it)) { Eats *eats = ecs_field(&it, Eats, 1); ecs_id_t pair = ecs_field_id(&it, 1); ecs_entity_t food = ecs_pair_second(ecs, pair); for (int i = 0; i < it.count; i ++) { printf("%s eats %d %s\n", ecs_get_name(ecs, it.entities[i]), eats[i].amount, ecs_get_name(ecs, food)); } } // Output: // Bob eats 10 Apples // Bob eats 5 Pears // Alice eats 4 Apples return ecs_fini(ecs); }