2022-05-16 13:53:20 +00:00
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//! Create an application without winit (runs single time, no event loop).
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2021-12-15 00:15:47 +00:00
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use bevy::prelude::*;
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use bevy::winit::WinitPlugin;
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fn main() {
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App::new()
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Plugins own their settings. Rework PluginGroup trait. (#6336)
# Objective
Fixes #5884 #2879
Alternative to #2988 #5885 #2886
"Immutable" Plugin settings are currently represented as normal ECS resources, which are read as part of plugin init. This presents a number of problems:
1. If a user inserts the plugin settings resource after the plugin is initialized, it will be silently ignored (and use the defaults instead)
2. Users can modify the plugin settings resource after the plugin has been initialized. This creates a false sense of control over settings that can no longer be changed.
(1) and (2) are especially problematic and confusing for the `WindowDescriptor` resource, but this is a general problem.
## Solution
Immutable Plugin settings now live on each Plugin struct (ex: `WindowPlugin`). PluginGroups have been reworked to support overriding plugin values. This also removes the need for the `add_plugins_with` api, as the `add_plugins` api can use the builder pattern directly. Settings that can be used at runtime continue to be represented as ECS resources.
Plugins are now configured like this:
```rust
app.add_plugin(AssetPlugin {
watch_for_changes: true,
..default()
})
```
PluginGroups are now configured like this:
```rust
app.add_plugins(DefaultPlugins
.set(AssetPlugin {
watch_for_changes: true,
..default()
})
)
```
This is an alternative to #2988, which is similar. But I personally prefer this solution for a couple of reasons:
* ~~#2988 doesn't solve (1)~~ #2988 does solve (1) and will panic in that case. I was wrong!
* This PR directly ties plugin settings to Plugin types in a 1:1 relationship, rather than a loose "setup resource" <-> plugin coupling (where the setup resource is consumed by the first plugin that uses it).
* I'm not a huge fan of overloading the ECS resource concept and implementation for something that has very different use cases and constraints.
## Changelog
- PluginGroups can now be configured directly using the builder pattern. Individual plugin values can be overridden by using `plugin_group.set(SomePlugin {})`, which enables overriding default plugin values.
- `WindowDescriptor` plugin settings have been moved to `WindowPlugin` and `AssetServerSettings` have been moved to `AssetPlugin`
- `app.add_plugins_with` has been replaced by using `add_plugins` with the builder pattern.
## Migration Guide
The `WindowDescriptor` settings have been moved from a resource to `WindowPlugin::window`:
```rust
// Old (Bevy 0.8)
app
.insert_resource(WindowDescriptor {
width: 400.0,
..default()
})
.add_plugins(DefaultPlugins)
// New (Bevy 0.9)
app.add_plugins(DefaultPlugins.set(WindowPlugin {
window: WindowDescriptor {
width: 400.0,
..default()
},
..default()
}))
```
The `AssetServerSettings` resource has been removed in favor of direct `AssetPlugin` configuration:
```rust
// Old (Bevy 0.8)
app
.insert_resource(AssetServerSettings {
watch_for_changes: true,
..default()
})
.add_plugins(DefaultPlugins)
// New (Bevy 0.9)
app.add_plugins(DefaultPlugins.set(AssetPlugin {
watch_for_changes: true,
..default()
}))
```
`add_plugins_with` has been replaced by `add_plugins` in combination with the builder pattern:
```rust
// Old (Bevy 0.8)
app.add_plugins_with(DefaultPlugins, |group| group.disable::<AssetPlugin>());
// New (Bevy 0.9)
app.add_plugins(DefaultPlugins.build().disable::<AssetPlugin>());
```
2022-10-24 21:20:33 +00:00
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.add_plugins(DefaultPlugins.build().disable::<WinitPlugin>())
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2021-12-15 00:15:47 +00:00
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.add_system(setup_system)
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.run();
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}
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fn setup_system(mut commands: Commands) {
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Spawn now takes a Bundle (#6054)
# Objective
Now that we can consolidate Bundles and Components under a single insert (thanks to #2975 and #6039), almost 100% of world spawns now look like `world.spawn().insert((Some, Tuple, Here))`. Spawning an entity without any components is an extremely uncommon pattern, so it makes sense to give spawn the "first class" ergonomic api. This consolidated api should be made consistent across all spawn apis (such as World and Commands).
## Solution
All `spawn` apis (`World::spawn`, `Commands:;spawn`, `ChildBuilder::spawn`, and `WorldChildBuilder::spawn`) now accept a bundle as input:
```rust
// before:
commands
.spawn()
.insert((A, B, C));
world
.spawn()
.insert((A, B, C);
// after
commands.spawn((A, B, C));
world.spawn((A, B, C));
```
All existing instances of `spawn_bundle` have been deprecated in favor of the new `spawn` api. A new `spawn_empty` has been added, replacing the old `spawn` api.
By allowing `world.spawn(some_bundle)` to replace `world.spawn().insert(some_bundle)`, this opened the door to removing the initial entity allocation in the "empty" archetype / table done in `spawn()` (and subsequent move to the actual archetype in `.insert(some_bundle)`).
This improves spawn performance by over 10%:
To take this measurement, I added a new `world_spawn` benchmark.
Unfortunately, optimizing `Commands::spawn` is slightly less trivial, as Commands expose the Entity id of spawned entities prior to actually spawning. Doing the optimization would (naively) require assurances that the `spawn(some_bundle)` command is applied before all other commands involving the entity (which would not necessarily be true, if memory serves). Optimizing `Commands::spawn` this way does feel possible, but it will require careful thought (and maybe some additional checks), which deserves its own PR. For now, it has the same performance characteristics of the current `Commands::spawn_bundle` on main.
**Note that 99% of this PR is simple renames and refactors. The only code that needs careful scrutiny is the new `World::spawn()` impl, which is relatively straightforward, but it has some new unsafe code (which re-uses battle tested BundlerSpawner code path).**
---
## Changelog
- All `spawn` apis (`World::spawn`, `Commands:;spawn`, `ChildBuilder::spawn`, and `WorldChildBuilder::spawn`) now accept a bundle as input
- All instances of `spawn_bundle` have been deprecated in favor of the new `spawn` api
- World and Commands now have `spawn_empty()`, which is equivalent to the old `spawn()` behavior.
## Migration Guide
```rust
// Old (0.8):
commands
.spawn()
.insert_bundle((A, B, C));
// New (0.9)
commands.spawn((A, B, C));
// Old (0.8):
commands.spawn_bundle((A, B, C));
// New (0.9)
commands.spawn((A, B, C));
// Old (0.8):
let entity = commands.spawn().id();
// New (0.9)
let entity = commands.spawn_empty().id();
// Old (0.8)
let entity = world.spawn().id();
// New (0.9)
let entity = world.spawn_empty();
```
2022-09-23 19:55:54 +00:00
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commands.spawn(Camera3dBundle::default());
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2021-12-15 00:15:47 +00:00
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}
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