# Objective
Allow `Gizmos` to work in `FixedUpdate` without any changes needed. This
changes `Gizmos` from being a purely immediate mode api, but allows the
user to use it as if it were an immediate mode API regardless of
schedule context.
Also allows for extending by other custom schedules by adding their own
`GizmoStorage<Clear>` and the requisite systems:
- `propagate_gizmos::<Clear>` before `update_gizmo_meshes`
- `stash_default_gizmos` when starting a clear context
- `pop_default_gizmos` when ending a clear context
- `collect_default_gizmos` when grabbing the requested gizmos
- `clear_gizmos` for clearing the context's gizmos
## Solution
Adds a generic to `Gizmos` that defaults to `Update` (the current way
gizmos works). When entering a new clear context the default `Gizmos`
gets swapped out for that context's duration so the context can collect
the gizmos requested.
Prior work: https://github.com/bevyengine/bevy/pull/9153
## To do
- [x] `FixedUpdate` should probably get its own First, Pre, Update,
Post, Last system sets for this. Otherwise users will need to make sure
to order their systems before `clear_gizmos`. This could alternatively
be fixed by moving the setup of this to `bevy_time::fixed`?
PR to fix this issue: https://github.com/bevyengine/bevy/pull/10977
- [x] use mem::take internally for the swaps?
- [x] Better name for the `Context` generic on gizmos? `Clear`?
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## Changelog
- Gizmos drawn in `FixedMain` now last until the next `FixedMain`
iteration runs.
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