bevy/examples/stress_tests
Marco Buono ef23f465ce
Do not re-check visibility or re-render shadow maps for point and spot lights for each view (#15156)
# Objective

_If I understand it correctly_, we were checking mesh visibility, as
well as re-rendering point and spot light shadow maps for each view.
This makes it so that M views and N lights produce M x N complexity.
This PR aims to fix that, as well as introduce a stress test for this
specific scenario.

## Solution

- Keep track of what lights have already had mesh visibility calculated
and do not calculate it again;
- Reuse shadow depth textures and attachments across all views, and only
render shadow maps for the _first_ time a light is encountered on a
view;
- Directional lights remain unaltered, since their shadow map cascades
are view-dependent;
- Add a new `many_cameras_lights` stress test example to verify the
solution

## Showcase

110% speed up on the stress test
83% reduction of memory usage in stress test

### Before (5.35 FPS on stress test)
<img width="1392" alt="Screenshot 2024-09-11 at 12 25 57"
src="https://github.com/user-attachments/assets/136b0785-e9a4-44df-9a22-f99cc465e126">

### After (11.34 FPS on stress test)
<img width="1392" alt="Screenshot 2024-09-11 at 12 24 35"
src="https://github.com/user-attachments/assets/b8dd858f-5e19-467f-8344-2b46ca039630">


## Testing

- Did you test these changes? If so, how? 
- On my game project where I have two cameras, and many shadow casting
lights I managed to get pretty much double the FPS.
  - Also included a stress test, see the comparison above
- Are there any parts that need more testing?
- Yes, I would like help verifying that this fix is indeed correct, and
that we were really re-rendering the shadow maps by mistake and it's
indeed okay to not do that
- How can other people (reviewers) test your changes? Is there anything
specific they need to know?
  - Run the `many_cameras_lights` example
- On the `main` branch, cherry pick the commit with the example (`git
cherry-pick --no-commit 1ed4ace01`) and run it
- If relevant, what platforms did you test these changes on, and are
there any important ones you can't test?
  - macOS

---------

Co-authored-by: François Mockers <francois.mockers@vleue.com>
2024-11-11 18:49:09 +00:00
..
bevymark.rs Merge Style properties into Node. Use ComputedNode for computed properties. (#15975) 2024-10-18 22:25:33 +00:00
many_animated_sprites.rs Move TextureAtlas into UiImage and remove impl Component for TextureAtlas (#16072) 2024-10-23 23:24:17 +00:00
many_buttons.rs UiImage -> ImageNode, UiImageSize -> ImageNodeSize (#16271) 2024-11-07 21:52:58 +00:00
many_cameras_lights.rs Do not re-check visibility or re-render shadow maps for point and spot lights for each view (#15156) 2024-11-11 18:49:09 +00:00
many_cubes.rs aligning public apis of Time,Timer and Stopwatch (#15962) 2024-10-16 21:09:32 +00:00
many_foxes.rs aligning public apis of Time,Timer and Stopwatch (#15962) 2024-10-16 21:09:32 +00:00
many_gizmos.rs Merge Style properties into Node. Use ComputedNode for computed properties. (#15975) 2024-10-18 22:25:33 +00:00
many_glyphs.rs Merge Style properties into Node. Use ComputedNode for computed properties. (#15975) 2024-10-18 22:25:33 +00:00
many_lights.rs Improve API for scaling orthographic cameras (#15969) 2024-10-17 17:50:06 +00:00
many_sprites.rs aligning public apis of Time,Timer and Stopwatch (#15962) 2024-10-16 21:09:32 +00:00
README.md Add a stress test profile (#6901) 2022-12-20 15:59:41 +00:00
text_pipeline.rs aligning public apis of Time,Timer and Stopwatch (#15962) 2024-10-16 21:09:32 +00:00
transform_hierarchy.rs aligning public apis of Time,Timer and Stopwatch (#15962) 2024-10-16 21:09:32 +00:00
warning_string.txt Added performance warning when running stress test examples in debug mode (#5029) 2022-07-13 19:13:46 +00:00

Stress tests

These examples are used to stress test Bevy's performance in various ways. These should be run with the "stress-test" profile to accurately represent performance in production, otherwise they will run in cargo's default "dev" profile which is very slow.

Example Command

cargo run --profile stress-test --example <EXAMPLE>