104 lines
3.5 KiB
Rust
104 lines
3.5 KiB
Rust
//! This example illustrates how to create UI text and update it in a system.
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//!
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//! It displays the current FPS in the top left corner, as well as text that changes color
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//! in the bottom right. For text within a scene, please see the text2d example.
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use bevy::{
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diagnostic::{DiagnosticsStore, FrameTimeDiagnosticsPlugin},
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prelude::*,
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};
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fn main() {
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App::new()
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.add_plugins((DefaultPlugins, FrameTimeDiagnosticsPlugin))
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.add_systems(Startup, setup)
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.add_systems(Update, (text_update_system, text_color_system))
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.run();
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}
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// A unit struct to help identify the FPS UI component, since there may be many Text components
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#[derive(Component)]
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struct FpsText;
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// A unit struct to help identify the color-changing Text component
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#[derive(Component)]
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struct ColorText;
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fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
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// UI camera
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commands.spawn(Camera2dBundle::default());
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// Text with one section
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commands.spawn((
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// Create a TextBundle that has a Text with a single section.
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TextBundle::from_section(
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// Accepts a `String` or any type that converts into a `String`, such as `&str`
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"hello\nbevy!",
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TextStyle {
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// This font is loaded and will be used instead of the default font.
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font: asset_server.load("fonts/FiraSans-Bold.ttf"),
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font_size: 100.0,
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color: Color::WHITE,
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},
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) // Set the alignment of the Text
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.with_text_alignment(TextAlignment::Center)
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// Set the style of the TextBundle itself.
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.with_style(Style {
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position_type: PositionType::Absolute,
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bottom: Val::Px(5.0),
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right: Val::Px(15.0),
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..default()
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}),
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ColorText,
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));
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// Text with multiple sections
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commands.spawn((
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// Create a TextBundle that has a Text with a list of sections.
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TextBundle::from_sections([
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TextSection::new(
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"FPS: ",
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TextStyle {
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// This font is loaded and will be used instead of the default font.
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font: asset_server.load("fonts/FiraSans-Bold.ttf"),
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font_size: 60.0,
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color: Color::WHITE,
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},
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),
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TextSection::from_style(TextStyle {
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font_size: 60.0,
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color: Color::GOLD,
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// If no font is specified, it will use the default font.
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..default()
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}),
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]),
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FpsText,
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));
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}
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fn text_color_system(time: Res<Time>, mut query: Query<&mut Text, With<ColorText>>) {
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for mut text in &mut query {
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let seconds = time.elapsed_seconds();
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// Update the color of the first and only section.
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text.sections[0].style.color = Color::Rgba {
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red: (1.25 * seconds).sin() / 2.0 + 0.5,
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green: (0.75 * seconds).sin() / 2.0 + 0.5,
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blue: (0.50 * seconds).sin() / 2.0 + 0.5,
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alpha: 1.0,
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};
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}
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}
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fn text_update_system(
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diagnostics: Res<DiagnosticsStore>,
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mut query: Query<&mut Text, With<FpsText>>,
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) {
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for mut text in &mut query {
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if let Some(fps) = diagnostics.get(FrameTimeDiagnosticsPlugin::FPS) {
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if let Some(value) = fps.smoothed() {
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// Update the value of the second section
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text.sections[1].value = format!("{value:.2}");
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}
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}
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}
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}
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