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Include more lifecycle info in storage docs

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Co-Authored-By: Trashtalk217 <24552941+Trashtalk217@users.noreply.github.com>
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Elliott Pierce 2025-07-10 13:10:42 -04:00
parent e9df3006df
commit 3fcbb24823
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crates/bevy_ecs/src/entity/mod.rs
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@ -155,6 +155,15 @@
//! It also stores more information like the [`Tick`] a row was last constructed or destructed, and the [`EntityIdLocation`] itself.
//! For more information about what's stored here, see [`Entities`], Bevy's implementation of this special column.
//!
//! Entity spawning is done in two stages:
//! First we create an entity id (alloc step), and then we construct it (add components and other metadata).
//! The reason for this is that we need to be able to assign entity ids concurrently,
//! while for construction we need exclusive (non-concurrent) access to the world.
//! That leaves three states for any given [`EntityRow`], where those two spawning stages serve to transition between states.
//! First, a row could be unallocated; only the allocator has any knowledge of this [`Entity`].
//! Second, the row is allocated, making it a "null" entity; it exists, and other code can have knowledge of its existence, but it is not constructed.
//! Third, the row is constructed, adding any (or no) components to the entity; it is now discoverable through queries, etc.
//!
//! [`World`]: crate::world::World
//! [`Query`]: crate::system::Query
//! [`Bundle`]: crate::bundle::Bundle