# Objective
Further speed up visibility checking by removing the main sources of contention for the system.
## Solution
- ~~Make `ComputedVisibility` a resource wrapping a `FixedBitset`.~~
- ~~Remove `ComputedVisibility` as a component.~~
~~This adds a one-bit overhead to every entity in the app world. For a game with 100,000 entities, this is 12.5KB of memory. This is still small enough to fit entirely in most L1 caches. Also removes the need for a per-Entity change detection tick. This reduces the memory footprint of ComputedVisibility 72x.~~
~~The decreased memory usage and less fragmented memory locality should provide significant performance benefits.~~
~~Clearing visible entities should be significantly faster than before:~~
- ~~Setting one `u32` to 0 clears 32 entities per cycle.~~
- ~~No archetype fragmentation to contend with.~~
- ~~Change detection is applied to the resource, so there is no per-Entity update tick requirement.~~
~~The side benefit of this design is that it removes one more "computed component" from userspace. Though accessing the values within it are now less ergonomic.~~
This PR changes `crossbeam_channel` in `check_visibility` to use a `Local<ThreadLocal<Cell<Vec<Entity>>>` to mark down visible entities instead.
Co-Authored-By: TheRawMeatball <therawmeatball@gmail.com>
Co-Authored-By: Aevyrie <aevyrie@gmail.com>
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