bevy/examples/dev_tools/fps_overlay.rs

//! Showcase how to use and configure FPS overlay.

use bevy::{
    dev_tools::fps_overlay::{FpsOverlayConfig, FpsOverlayPlugin},
    prelude::*,
};

struct OverlayColor;

impl OverlayColor {
    const RED: Color = Color::srgb(1.0, 0.0, 0.0);
    const GREEN: Color = Color::srgb(0.0, 1.0, 0.0);
}

fn main() {
    App::new()
        .add_plugins((
            DefaultPlugins,
            FpsOverlayPlugin {
                config: FpsOverlayConfig {
                    text_config: TextStyle {
                        // Here we define size of our overlay
                        font_size: 42.0,
                        // We can also change color of the overlay
                        color: OverlayColor::GREEN,
                        // If we want, we can use a custom font
                        font: default(),
                    },
                    enabled: true,
                },
            },
        ))
        .add_systems(Startup, setup)
        .add_systems(Update, customize_config)
        .run();
}

fn setup(mut commands: Commands) {
    // We need to spawn a camera (2d or 3d) to see the overlay
    commands.spawn(Camera2d);

    // Instruction text
    commands
        .spawn(NodeBundle {
            style: Style {
                width: Val::Percent(100.0),
                height: Val::Percent(100.0),
                align_items: AlignItems::Center,
                justify_content: JustifyContent::Center,
                ..default()
            },
            ..default()
        })
        .with_children(|c| {
            c.spawn(TextBundle::from_section(
                concat!(
                    "Press 1 to toggle the overlay color.\n",
                    "Press 2 to decrease the overlay size.\n",
                    "Press 3 to increase the overlay size.\n",
                    "Press 4 to toggle the overlay visibility."
                ),
                TextStyle::default(),
            ));
        });
}

fn customize_config(input: Res<ButtonInput<KeyCode>>, mut overlay: ResMut<FpsOverlayConfig>) {
    if input.just_pressed(KeyCode::Digit1) {
        // Changing resource will affect overlay
        if overlay.text_config.color == OverlayColor::GREEN {
            overlay.text_config.color = OverlayColor::RED;
        } else {
            overlay.text_config.color = OverlayColor::GREEN;
        }
    }
    if input.just_pressed(KeyCode::Digit2) {
        overlay.text_config.font_size -= 2.0;
    }
    if input.just_pressed(KeyCode::Digit3) {
        overlay.text_config.font_size += 2.0;
    }
    if input.just_pressed(KeyCode::Digit4) {
        overlay.enabled = !overlay.enabled;
    }
}