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https://github.com/bevyengine/bevy
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174819be83
# Objective
Allow more use cases where the user may benefit from both `ExtractComponentPlugin` _and_ `UniformComponentPlugin`.
## Solution
Add an associated type to `ExtractComponent` in order to allow specifying the output component (or bundle).
Make `extract_component` return an `Option<_>` such that components can be extracted only when needed.
What problem does this solve?
`ExtractComponentPlugin` allows extracting components, but currently the output type is the same as the input.
This means that use cases such as having a settings struct which turns into a uniform is awkward.
For example we might have:
```rust
struct MyStruct {
enabled: bool,
val: f32
}
struct MyStructUniform {
val: f32
}
```
With the new approach, we can extract `MyStruct` only when it is enabled, and turn it into its related uniform.
This chains well with `UniformComponentPlugin`.
The user may then:
```rust
app.add_plugin(ExtractComponentPlugin::<MyStruct>::default());
app.add_plugin(UniformComponentPlugin::<MyStructUniform>::default());
```
This then saves the user a fair amount of boilerplate.
## Changelog
### Changed
- `ExtractComponent` can specify output type, and outputting is optional.
Co-authored-by: Torstein Grindvik <52322338+torsteingrindvik@users.noreply.github.com>
38 lines
1 KiB
Rust
38 lines
1 KiB
Rust
//! Configuration for cameras related to UI.
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use bevy_ecs::component::Component;
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use bevy_ecs::prelude::With;
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use bevy_ecs::query::QueryItem;
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use bevy_render::camera::Camera;
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use bevy_render::extract_component::ExtractComponent;
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/// Configuration for cameras related to UI.
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///
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/// When a [`Camera`] doesn't have the [`UiCameraConfig`] component,
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/// it will display the UI by default.
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///
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/// [`Camera`]: bevy_render::camera::Camera
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#[derive(Component, Clone)]
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pub struct UiCameraConfig {
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/// Whether to output UI to this camera view.
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///
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/// When a `Camera` doesn't have the [`UiCameraConfig`] component,
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/// it will display the UI by default.
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pub show_ui: bool,
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}
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impl Default for UiCameraConfig {
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fn default() -> Self {
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Self { show_ui: true }
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}
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}
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impl ExtractComponent for UiCameraConfig {
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type Query = &'static Self;
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type Filter = With<Camera>;
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type Out = Self;
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fn extract_component(item: QueryItem<'_, Self::Query>) -> Option<Self> {
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Some(item.clone())
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}
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}
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