Move render app init and extraction to separate plugin by kristoff3r · Pull Request #22758 · bevyengine/bevy

kristoff3r · 2026-01-31T21:53:42Z

Objective

Currently in bevy_render the renderer initialization (e.g. creating a surface, registering rendering systems) is very intertwined with setting up the extraction logic itself (e.g. how is data moved between the worlds, how are they kept in sync). This makes it harder to understand both things, and also makes it very hard to test the extraction logic, as you don't want to start the renderer in unit test.

In the future this functionality might even be useful for the ECS outside bevy_render, e.g. for custom renderers that want to use a render world, or for multi world setups.

Solution

This PR splits out creation of the render subapp plus the extraction logic itself into ExtractPlugin, and uses the new found flexibility to finally add a test for it.

This is the first part in a series of PRs I plan to do to:

Separate the extraction logic so it's possible to test (this one)
Fix the bug that's currently commented out in the test
Rework the Extract trait to bypass the orphan rules, so we can use it everywhere (speculative but I have an idea)

Testing

Added a test to show that extraction is working.

I also ran a bunch of examples requiring rendering and they still work.

alice-i-cecile

I like separating these, and this appears to have been done correctly.

crates/bevy_render/src/error_handler.rs

crates/bevy_render/src/extract_plugin.rs

crates/bevy_render/src/lib.rs

kristoff3r · 2026-02-06T11:22:21Z

I disentangled the 2 plugins a bit more, let me know what you think. I haven't worked that much with schedule creation before, and I didn't realize you have to be careful about ordering when doing .add_schedule. I added a warning that would have saved me 30 minutes 😄

Now the only render specific things are the RenderApp label, and that it creates and uses the Render schedule.

crates/bevy_app/src/sub_app.rs

crates/bevy_render/src/extract_plugin.rs

crates/bevy_render/src/lib.rs

Co-authored-by: atlv <email@atlasdostal.com>

@atlv24

# Objective Fixes #18722, and allows `ExtractComponent` to be used for foreign types. ## Solution * Split the `Out` type from `ExtractComponent` to a `SyncComponent` trait. This allows types to use the synchronization logic without the extraction logic, and allows `SyncComponentPlugin` to correctly identify which components should be removed. * Don't delete the entire entity but only the `Out` components in `SyncComponentPlugin`/`SyncWorldPlugin`, fixing #18722. * Add marker types to `ExtractComponent` and `SyncComponent`, allowing them to be implemented for foreign types outside `bevy_render`. (Example: `DirectionalLight` is defined in `bevy_light` which doesn't depend on `bevy_render`, and used by `bevy_pbr`. Without the marker no crate is allowed to implement the trait.) During some earlier render crate refactors by @atlv24, some uses of `ExtractComponent` was converted to manual implementations. I have not ported these back, that can be done in follow up PRs. As a follow up it might be interesting to make a derive macro for `SyncComponent`, and/or update the `ExtractComponent` macro to be able to customize the behavior around syncing. ## Testing Ran a bunch of the examples. It would be good to test others, especially ones that toggle components. ~~A test case is in #22758. If that one gets merged first this PR should be updated to uncomment the relevant assert.~~ edit: the assert has been added.

Move render app init and extraction to separate plugin

042a92c

kristoff3r added A-Rendering Drawing game state to the screen C-Code-Quality A section of code that is hard to understand or change S-Needs-Review Needs reviewer attention (from anyone!) to move forward labels Jan 31, 2026

github-project-automation bot added this to Rendering (Old) Jan 31, 2026

alice-i-cecile requested a review from atlv24 January 31, 2026 22:06

alice-i-cecile added the A-Windowing Platform-agnostic interface layer to run your app in label Jan 31, 2026

kristoff3r added 2 commits January 31, 2026 23:18

Fix no_renderer example

8f56128

Fix docs

e0a7378

kristoff3r mentioned this pull request Feb 1, 2026

Refactor extraction to bypass the orphan rules #22766

Merged

kristoff3r removed the A-Windowing Platform-agnostic interface layer to run your app in label Feb 1, 2026

alice-i-cecile added the M-Migration-Guide A breaking change to Bevy's public API that needs to be noted in a migration guide label Feb 2, 2026

kristoff3r added 2 commits February 5, 2026 23:53

Merge branch 'main' into ks/extract_plugin

bdaa3d9

Fix some bugs

36069a3

alice-i-cecile approved these changes Feb 5, 2026

View reviewed changes

kristoff3r added 2 commits February 6, 2026 00:26

clippy be quiet plz

3a8908f

Used wrong Instant type

6bd2970