bevy/examples/stress_tests
Brian Reavis 6b40b6749e
RenderAssetPersistencePolicy → RenderAssetUsages (#11399)
# Objective

Right now, all assets in the main world get extracted and prepared in
the render world (if the asset's using the RenderAssetPlugin). This is
unfortunate for two cases:

1. **TextureAtlas** / **FontAtlas**: This one's huge. The individual
`Image` assets that make up the atlas are cloned and prepared
individually when there's no reason for them to be. The atlas textures
are built on the CPU in the main world. *There can be hundreds of images
that get prepared for rendering only not to be used.*
2. If one loads an Image and needs to transform it in a system before
rendering it, kind of like the [decompression
example](https://github.com/bevyengine/bevy/blob/main/examples/asset/asset_decompression.rs#L120),
there's a price paid for extracting & preparing the asset that's not
intended to be rendered yet.

------

* References #10520
* References #1782

## Solution

This changes the `RenderAssetPersistencePolicy` enum to bitflags. I felt
that the objective with the parameter is so similar in nature to wgpu's
[`TextureUsages`](https://docs.rs/wgpu/latest/wgpu/struct.TextureUsages.html)
and
[`BufferUsages`](https://docs.rs/wgpu/latest/wgpu/struct.BufferUsages.html),
that it may as well be just like that.

```rust
// This asset only needs to be in the main world. Don't extract and prepare it.
RenderAssetUsages::MAIN_WORLD

// Keep this asset in the main world and  
RenderAssetUsages::MAIN_WORLD | RenderAssetUsages::RENDER_WORLD

// This asset is only needed in the render world. Remove it from the asset server once extracted.
RenderAssetUsages::RENDER_WORLD
```

### Alternate Solution

I considered introducing a third field to `RenderAssetPersistencePolicy`
enum:
```rust
enum RenderAssetPersistencePolicy {
    /// Keep the asset in the main world after extracting to the render world.
    Keep,
    /// Remove the asset from the main world after extracting to the render world.
    Unload,
    /// This doesn't need to be in the render world at all.
    NoExtract, // <-----
}
```
Functional, but this seemed like shoehorning. Another option is renaming
the enum to something like:
```rust
enum RenderAssetExtractionPolicy {
    /// Extract the asset and keep it in the main world.
    Extract,
    /// Remove the asset from the main world after extracting to the render world.
    ExtractAndUnload,
    /// This doesn't need to be in the render world at all.
    NoExtract,
}
```
I think this last one could be a good option if the bitflags are too
clunky.

## Migration Guide

* `RenderAssetPersistencePolicy::Keep` → `RenderAssetUsage::MAIN_WORLD |
RenderAssetUsage::RENDER_WORLD` (or `RenderAssetUsage::default()`)
* `RenderAssetPersistencePolicy::Unload` →
`RenderAssetUsage::RENDER_WORLD`
* For types implementing the `RenderAsset` trait, change `fn
persistence_policy(&self) -> RenderAssetPersistencePolicy` to `fn
asset_usage(&self) -> RenderAssetUsages`.
* Change any references to `cpu_persistent_access`
(`RenderAssetPersistencePolicy`) to `asset_usage` (`RenderAssetUsage`).
This applies to `Image`, `Mesh`, and a few other types.
2024-01-30 13:22:10 +00:00
..
bevymark.rs RenderAssetPersistencePolicy → RenderAssetUsages (#11399) 2024-01-30 13:22:10 +00:00
many_animated_sprites.rs Texture Atlas rework (#5103) 2024-01-16 13:59:08 +00:00
many_buttons.rs Fix panic in examples using argh on the web (#11513) 2024-01-24 21:16:10 +00:00
many_cubes.rs RenderAssetPersistencePolicy → RenderAssetUsages (#11399) 2024-01-30 13:22:10 +00:00
many_foxes.rs Fix panic in examples using argh on the web (#11513) 2024-01-24 21:16:10 +00:00
many_gizmos.rs Replace DiagnosticId by DiagnosticPath (#9266) 2024-01-20 15:42:51 +00:00
many_glyphs.rs Rename TextAlignment to JustifyText. (#10854) 2023-12-05 03:00:41 +00:00
many_lights.rs Use impl Into<A> for Assets::add (#10878) 2024-01-08 22:14:43 +00:00
many_sprites.rs Use a consistent scale factor and resolution in stress tests (#10474) 2023-11-09 22:05:32 +00:00
README.md Add a stress test profile (#6901) 2022-12-20 15:59:41 +00:00
text_pipeline.rs Rename TextAlignment to JustifyText. (#10854) 2023-12-05 03:00:41 +00:00
transform_hierarchy.rs Remove some old references to CoreSet (#9833) 2023-09-18 01:07:11 +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>