bevy/examples/ui/text.rs
Carter Anderson 81b53d15d4 Make Commands and World apis consistent (#1703)
Resolves #1253 #1562

This makes the Commands apis consistent with World apis. This moves to a "type state" pattern (like World) where the "current entity" is stored in an `EntityCommands` builder.

In general this tends to cuts down on indentation and line count. It comes at the cost of needing to type `commands` more and adding more semicolons to terminate expressions.

I also added `spawn_bundle` to Commands because this is a common enough operation that I think its worth providing a shorthand.
2021-03-23 00:23:40 +00:00

117 lines
4.3 KiB
Rust

use bevy::{
diagnostic::{Diagnostics, FrameTimeDiagnosticsPlugin},
prelude::*,
};
/// This example illustrates how to create UI text and update it in a system. It displays the
/// current FPS in the top left corner, as well as text that changes colour in the bottom right.
/// For text within a scene, please see the text2d example.
fn main() {
App::build()
.add_plugins(DefaultPlugins)
.add_plugin(FrameTimeDiagnosticsPlugin::default())
.add_startup_system(setup.system())
.add_system(text_update_system.system())
.add_system(text_color_system.system())
.run();
}
// A unit struct to help identify the FPS UI component, since there may be many Text components
struct FpsText;
// A unit struct to help identify the color-changing Text component
struct ColorText;
fn setup(mut commands: Commands, asset_server: Res<AssetServer>) {
// UI camera
commands.spawn_bundle(UiCameraBundle::default());
// Text with one section
commands
.spawn_bundle(TextBundle {
style: Style {
align_self: AlignSelf::FlexEnd,
position_type: PositionType::Absolute,
position: Rect {
bottom: Val::Px(5.0),
right: Val::Px(15.0),
..Default::default()
},
..Default::default()
},
// Use the `Text::with_section` constructor
text: Text::with_section(
// Accepts a `String` or any type that converts into a `String`, such as `&str`
"hello\nbevy!",
TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
font_size: 100.0,
color: Color::WHITE,
},
// Note: You can use `Default::default()` in place of the `TextAlignment`
TextAlignment {
horizontal: HorizontalAlign::Center,
..Default::default()
},
),
..Default::default()
})
.insert(ColorText);
// Rich text with multiple sections
commands
.spawn_bundle(TextBundle {
style: Style {
align_self: AlignSelf::FlexEnd,
..Default::default()
},
// Use `Text` directly
text: Text {
// Construct a `Vec` of `TextSection`s
sections: vec![
TextSection {
value: "FPS: ".to_string(),
style: TextStyle {
font: asset_server.load("fonts/FiraSans-Bold.ttf"),
font_size: 60.0,
color: Color::WHITE,
},
},
TextSection {
value: "".to_string(),
style: TextStyle {
font: asset_server.load("fonts/FiraMono-Medium.ttf"),
font_size: 60.0,
color: Color::GOLD,
},
},
],
..Default::default()
},
..Default::default()
})
.insert(FpsText);
}
fn text_update_system(diagnostics: Res<Diagnostics>, mut query: Query<&mut Text, With<FpsText>>) {
for mut text in query.iter_mut() {
if let Some(fps) = diagnostics.get(FrameTimeDiagnosticsPlugin::FPS) {
if let Some(average) = fps.average() {
// Update the value of the second section
text.sections[1].value = format!("{:.2}", average);
}
}
}
}
fn text_color_system(time: Res<Time>, mut query: Query<&mut Text, With<ColorText>>) {
for mut text in query.iter_mut() {
let seconds = time.seconds_since_startup() as f32;
// We used the `Text::with_section` helper method, but it is still just a `Text`,
// so to update it, we are still updating the one and only section
text.sections[0].style.color = Color::Rgba {
red: (1.25 * seconds).sin() / 2.0 + 0.5,
green: (0.75 * seconds).sin() / 2.0 + 0.5,
blue: (0.50 * seconds).sin() / 2.0 + 0.5,
alpha: 1.0,
};
}
}