mirror of
https://github.com/bevyengine/bevy
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67 lines
3.1 KiB
Rust
67 lines
3.1 KiB
Rust
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use crate::{
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component::Component,
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entity::{Entity, EntityMap, EntityMapper, MapEntities},
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world::World,
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};
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use bevy_reflect::FromType;
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/// For a specific type of component, this maps any fields with values of type [`Entity`] to a new world.
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/// Since a given `Entity` ID is only valid for the world it came frome, when performing deserialization
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/// any stored IDs need to be re-allocated in the destination world.
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///
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/// See [`MapEntities`] for more information.
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#[derive(Clone)]
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pub struct ReflectMapEntities {
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map_all_entities: fn(&mut World, &mut EntityMapper),
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map_entities: fn(&mut World, &mut EntityMapper, &[Entity]),
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}
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impl ReflectMapEntities {
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/// A general method for applying [`MapEntities`] behavior to all elements in an [`EntityMap`].
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///
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/// Be mindful in its usage: Works best in situations where the entities in the [`EntityMap`] are newly
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/// created, before systems have a chance to add new components. If some of the entities referred to
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/// by the [`EntityMap`] might already contain valid entity references, you should use [`map_entities`](Self::map_entities).
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///
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/// An example of this: A scene can be loaded with `Parent` components, but then a `Parent` component can be added
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/// to these entities after they have been loaded. If you reload the scene using [`map_all_entities`](Self::map_all_entities), those `Parent`
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/// components with already valid entity references could be updated to point at something else entirely.
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pub fn map_all_entities(&self, world: &mut World, entity_map: &mut EntityMap) {
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entity_map.world_scope(world, self.map_all_entities);
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}
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/// A general method for applying [`MapEntities`] behavior to elements in an [`EntityMap`]. Unlike
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/// [`map_all_entities`](Self::map_all_entities), this is applied to specific entities, not all values
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/// in the [`EntityMap`].
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///
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/// This is useful mostly for when you need to be careful not to update components that already contain valid entity
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/// values. See [`map_all_entities`](Self::map_all_entities) for more details.
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pub fn map_entities(&self, world: &mut World, entity_map: &mut EntityMap, entities: &[Entity]) {
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entity_map.world_scope(world, |world, mapper| {
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(self.map_entities)(world, mapper, entities);
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});
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}
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}
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impl<C: Component + MapEntities> FromType<C> for ReflectMapEntities {
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fn from_type() -> Self {
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ReflectMapEntities {
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map_entities: |world, entity_mapper, entities| {
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for &entity in entities {
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if let Some(mut component) = world.get_mut::<C>(entity) {
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component.map_entities(entity_mapper);
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}
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}
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},
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map_all_entities: |world, entity_mapper| {
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let entities = entity_mapper.get_map().values().collect::<Vec<Entity>>();
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for entity in &entities {
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if let Some(mut component) = world.get_mut::<C>(*entity) {
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component.map_entities(entity_mapper);
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}
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}
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},
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}
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}
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}
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