Bevy adapt desktop to mobile

When to use

Load this when a desktop window game must accept touch and a smaller layout. Platform features are on bevy-platform-mobile.

ECS shape

• Input: Touches lists active contacts. Action mapping lives on bevy-input-handling.
• UI: enlarge Node hit targets and pad the root with a safe-inset Resource. WindowResolution sets the logical size and an optional scale-factor override. WindowScaleFactorChanged reports a live dpi change.
• Textures: ASTC is a compressed texture format for mobile GPUs. Upload still goes through Assets<Image>.

fn configure_window(mut windows: Query<&mut Window>) {
    let Ok(mut window) = windows.single_mut() else {
        return;
    };
    window.resolution.set(720.0, 1280.0);
    window.resolution.set_scale_factor_override(Some(2.0));
}

#[derive(Resource, Default)]
struct LastTouch(Option<Vec2>);

fn track_touch(touches: Res<Touches>, mut last: ResMut<LastTouch>) {
    last.0 = touches.iter().next().map(|touch| touch.position());
}

#[derive(Component)]
struct TouchTarget;

#[derive(Component)]
struct HudRoot;

#[derive(Resource)]
struct SafeInsets {
    top: f32,
    bottom: f32,
}

fn enlarge_targets(mut nodes: Query<&mut Node, With<TouchTarget>>) {
    for mut node in &mut nodes {
        node.min_width = Val::Px(88.0);
        node.min_height = Val::Px(88.0);
    }
}

fn pad_hud(insets: Res<SafeInsets>, mut roots: Query<&mut Node, With<HudRoot>>) {
    for mut node in &mut roots {
        node.padding = UiRect {
            top: Val::Px(insets.top),
            bottom: Val::Px(insets.bottom),
            left: Val::Px(12.0),
            right: Val::Px(12.0),
        };
    }
}

use bevy::window::WindowScaleFactorChanged;