examples/queries/
query_component_inheritance.rs

1use crate::z_ignore_test_common::*;
2
3use flecs_ecs::prelude::*;
4// This example shows how queries can be used to match simple inheritance trees.
5
6#[derive(Component)]
7struct Unit;
8
9#[derive(Component)]
10struct CombatUnit;
11
12#[derive(Component)]
13struct MeleeUnit;
14
15#[derive(Component)]
16struct RangedUnit;
17
18#[derive(Component)]
19struct Warrior;
20
21#[derive(Component)]
22struct Wizard;
23
24#[derive(Component)]
25struct Marksman;
26
27#[derive(Component)]
28struct BuilderX;
29
30fn main() {
31    let world = World::new();
32
33    // Make the ECS aware of the inheritance relationships. Note that IsA
34    // relationship used here is the same as in the prefab example.
35    world.component::<CombatUnit>().is_a::<Unit>();
36    world.component::<MeleeUnit>().is_a::<CombatUnit>();
37    world.component::<RangedUnit>().is_a::<CombatUnit>();
38
39    world.component::<Warrior>().is_a::<MeleeUnit>();
40    world.component::<Wizard>().is_a::<RangedUnit>();
41    world.component::<Marksman>().is_a::<RangedUnit>();
42    world.component::<BuilderX>().is_a::<Unit>();
43
44    // Create a few units
45    world.entity_named("warrior_1").add::<Warrior>();
46    world.entity_named("warrior_2").add::<Warrior>();
47
48    world.entity_named("marksman_1").add::<Marksman>();
49    world.entity_named("marksman_2").add::<Marksman>();
50
51    world.entity_named("wizard_1").add::<Wizard>();
52    world.entity_named("wizard_2").add::<Wizard>();
53
54    world.entity_named("builder_1").add::<BuilderX>();
55    world.entity_named("builder_2").add::<BuilderX>();
56
57    // Create a rule to find all ranged units
58    let r = world.query::<&RangedUnit>().build();
59
60    // Iterate the rule
61    r.each_entity(|e, rangedunit| {
62        println!("Unit {} found", e.name());
63    });
64
65    // Output:
66    //  Unit wizard_1 found
67    //  Unit wizard_2 found
68    //  Unit marksman_1 found
69    //  Unit marksman_2 found
70}
71
72#[cfg(feature = "flecs_nightly_tests")]
73#[test]
74fn test() {
75    let output_capture = OutputCapture::capture().unwrap();
76    main();
77    output_capture.test("query_component_inheritance".to_string());
78}
examples/queries/query_component_inheritance.rs

examples/queries/
query_component_inheritance.rs
