desktop_request_redraw.rs

//! Desktop request redraw
use bevy::{
    dev_tools::fps_overlay::{FpsOverlayConfig, FpsOverlayPlugin},
    prelude::*,
    window::RequestRedraw,
    winit::WinitSettings,
};

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_plugins(MeshPickingPlugin)
        // Enable the FPS overlay with a high resolution refresh interval. This makes it
        // easier to validate that UpdateMode is behaving correctly when desktop_app is used.
        // The FPS counter should essentially pause when the cube is not rotating and should
        // update rapidly when the cube is rotating or there is input (e.g. moving the mouse).
        //
        // Left and Right clicking the cube should roggle rotation on/off.
        .add_plugins(FpsOverlayPlugin {
            config: FpsOverlayConfig {
                text_config: TextFont {
                    font_size: 12.0,
                    ..default()
                },
                text_color: Color::srgb(0.0, 1.0, 0.0),
                refresh_interval: core::time::Duration::from_millis(16),
                ..default()
            },
        })
        .insert_resource(WinitSettings::desktop_app())
        .add_systems(Startup, setup)
        .add_systems(Update, (update, redraw.after(update)))
        .run();
}

#[derive(Component)]
struct AnimationActive;

fn setup(
    mut commands: Commands,
    mut meshes: ResMut<Assets<Mesh>>,
    mut materials: ResMut<Assets<StandardMaterial>>,
) {
    commands.spawn((
        Camera3d::default(),
        Transform::from_xyz(0.0, 5.0, 0.0).looking_at(Vec3::ZERO, Vec3::Y),
    ));

    commands.spawn((
        PointLight {
            intensity: 1e6,
            ..Default::default()
        },
        Transform::from_xyz(-1.0, 5.0, 1.0),
    ));

    let node = Node {
        display: Display::Block,
        padding: UiRect::all(Val::Px(10.0)),
        row_gap: Val::Px(10.0),
        ..Default::default()
    };

    commands.spawn((
        node.clone(),
        children![
            (
                node.clone(),
                children![Text::new("Right click cube to pause animation")]
            ),
            (
                node.clone(),
                children![Text::new("Left click cube to start animation")]
            )
        ],
    ));

    commands
        .spawn((
            Mesh3d(meshes.add(Cuboid::from_length(1.0))),
            MeshMaterial3d(materials.add(Color::WHITE)),
            AnimationActive,
        ))
        .observe(
            |trigger: On<Pointer<Click>>, mut commands: Commands| match trigger.button {
                PointerButton::Primary => {
                    commands.entity(trigger.entity()).insert(AnimationActive);
                }
                PointerButton::Secondary => {
                    commands
                        .entity(trigger.entity())
                        .remove::<AnimationActive>();
                }
                _ => {}
            },
        );
}

fn update(time: Res<Time>, mut query: Query<&mut Transform, With<AnimationActive>>) {
    if let Ok(mut transform) = query.single_mut() {
        transform.rotate_x(time.delta_secs().min(1.0 / 60.0));
    }
}

fn redraw(mut commands: Commands, query: Query<Entity, With<AnimationActive>>) {
    if query.iter().next().is_some() {
        commands.write_event(RequestRedraw);
    }
}