mirror of
https://github.com/bevyengine/bevy
synced 2024-11-22 12:43:34 +00:00
6f7d0e5725
# Objective
Currently text is recomputed unnecessarily on any changes to its color,
which is extremely expensive.
## Solution
Split up `TextStyle` into two separate components `TextFont` and
`TextColor`.
## Testing
I added this system to `many_buttons`:
```rust
fn set_text_colors_changed(mut colors: Query<&mut TextColor>) {
for mut text_color in colors.iter_mut() {
text_color.set_changed();
}
}
```
reports ~4fps on main, ~50fps with this PR.
## Migration Guide
`TextStyle` has been renamed to `TextFont` and its `color` field has
been moved to a separate component named `TextColor` which newtypes
`Color`.
112 lines
3.3 KiB
Rust
112 lines
3.3 KiB
Rust
//! This example illustrates how `FontAtlas`'s are populated.
|
|
//! Bevy uses `FontAtlas`'s under the hood to optimize text rendering.
|
|
|
|
use bevy::{color::palettes::basic::YELLOW, prelude::*, text::FontAtlasSets};
|
|
use rand::{Rng, SeedableRng};
|
|
use rand_chacha::ChaCha8Rng;
|
|
|
|
fn main() {
|
|
App::new()
|
|
.init_resource::<State>()
|
|
.insert_resource(ClearColor(Color::BLACK))
|
|
.add_plugins(DefaultPlugins)
|
|
.add_systems(Startup, setup)
|
|
.add_systems(Update, (text_update_system, atlas_render_system))
|
|
.run();
|
|
}
|
|
|
|
#[derive(Resource)]
|
|
struct State {
|
|
atlas_count: u32,
|
|
handle: Handle<Font>,
|
|
timer: Timer,
|
|
}
|
|
|
|
impl Default for State {
|
|
fn default() -> Self {
|
|
Self {
|
|
atlas_count: 0,
|
|
handle: Handle::default(),
|
|
timer: Timer::from_seconds(0.05, TimerMode::Repeating),
|
|
}
|
|
}
|
|
}
|
|
|
|
#[derive(Resource, Deref, DerefMut)]
|
|
struct SeededRng(ChaCha8Rng);
|
|
|
|
fn atlas_render_system(
|
|
mut commands: Commands,
|
|
mut state: ResMut<State>,
|
|
font_atlas_sets: Res<FontAtlasSets>,
|
|
) {
|
|
if let Some(set) = font_atlas_sets.get(&state.handle) {
|
|
if let Some((_size, font_atlas)) = set.iter().next() {
|
|
let x_offset = state.atlas_count as f32;
|
|
if state.atlas_count == font_atlas.len() as u32 {
|
|
return;
|
|
}
|
|
let font_atlas = &font_atlas[state.atlas_count as usize];
|
|
state.atlas_count += 1;
|
|
commands.spawn(ImageBundle {
|
|
image: font_atlas.texture.clone().into(),
|
|
style: Style {
|
|
position_type: PositionType::Absolute,
|
|
top: Val::ZERO,
|
|
left: Val::Px(512.0 * x_offset),
|
|
..default()
|
|
},
|
|
..default()
|
|
});
|
|
}
|
|
}
|
|
}
|
|
|
|
fn text_update_system(
|
|
mut state: ResMut<State>,
|
|
time: Res<Time>,
|
|
mut query: Query<&mut Text>,
|
|
mut seeded_rng: ResMut<SeededRng>,
|
|
) {
|
|
if state.timer.tick(time.delta()).finished() {
|
|
for mut text in &mut query {
|
|
let c = seeded_rng.gen::<u8>() as char;
|
|
let string = &mut **text;
|
|
if !string.contains(c) {
|
|
string.push(c);
|
|
}
|
|
}
|
|
|
|
state.timer.reset();
|
|
}
|
|
}
|
|
|
|
fn setup(mut commands: Commands, asset_server: Res<AssetServer>, mut state: ResMut<State>) {
|
|
let font_handle = asset_server.load("fonts/FiraSans-Bold.ttf");
|
|
state.handle = font_handle.clone();
|
|
commands.spawn(Camera2d);
|
|
commands
|
|
.spawn(NodeBundle {
|
|
background_color: Color::NONE.into(),
|
|
style: Style {
|
|
position_type: PositionType::Absolute,
|
|
bottom: Val::ZERO,
|
|
..default()
|
|
},
|
|
..default()
|
|
})
|
|
.with_children(|parent| {
|
|
parent.spawn((
|
|
Text::new("a"),
|
|
TextFont {
|
|
font: font_handle,
|
|
font_size: 50.0,
|
|
..default()
|
|
},
|
|
TextColor(YELLOW.into()),
|
|
));
|
|
});
|
|
// We're seeding the PRNG here to make this example deterministic for testing purposes.
|
|
// This isn't strictly required in practical use unless you need your app to be deterministic.
|
|
commands.insert_resource(SeededRng(ChaCha8Rng::seed_from_u64(19878367467713)));
|
|
}
|