How to draw with Hatching for dashed/dotted lines?

[mattzque]

As far as I understand it, Lyon supports dashed lines via the hatching module in lyon_algorithms, but I couldn't get this to work in bevy with this crate. Algorithms is already a dependency (although not exported).

Does anyone know how to do that / has an example of how to accomplish this?

What I tried was:

[dependencies]
bevy = "0.12.1"
bevy_prototype_lyon = "0.10.0"
lyon_algorithms = "1"

use bevy::prelude::*;
use bevy_prototype_lyon::{
    draw::Stroke, entity::{Path, ShapeBundle}, geometry::GeometryBuilder, plugin::ShapePlugin, shapes::Line
};
use lyon_algorithms::{
    geom::LineSegment,
    hatching::{HatchSegment, Hatcher, HatchingOptions, RegularHatchingPattern},
    path::Path as LyonPath,
};

fn setup(mut commands: Commands) {
    commands.spawn(Camera2dBundle::default());

    // ***********************************************************************

    let shape = Line(Vec2::ZERO, Vec2::new(100.0, 0.0));

    commands.spawn((
        ShapeBundle {
            path: GeometryBuilder::build_as(&shape),
            ..default()
        },
        Stroke::new(Color::WHITE, 10.0),
    ));

    // ***********************************************************************
    // works:

    let shape = Line(Vec2::ZERO, Vec2::new(100.0, 0.0));

    let original_path = GeometryBuilder::build_as(&shape).0;

    commands.spawn((
        ShapeBundle {
            path: Path(original_path),
            spatial: SpatialBundle {
                transform: Transform::from_translation(Vec3::new(0.0, 100.0, 1.0)),
                ..default()
            },
            ..default()
        },
        Stroke::new(Color::BLUE, 10.0),
    ));

    // ***********************************************************************
    // this renders nothing:

    let shape = Line(Vec2::ZERO, Vec2::new(100.0, 0.0));

    let original_path = GeometryBuilder::build_as(&shape).0;

    let mut hatches = LyonPath::builder();
    let mut hatcher = Hatcher::new();
    hatcher.hatch_path(
        original_path.iter(),
        &HatchingOptions::DEFAULT,
        &mut RegularHatchingPattern {
            interval: 1.0,
            callback: &mut |segment: &HatchSegment| {
                hatches.add_line_segment(&LineSegment {
                    from: segment.a.position,
                    to: segment.b.position,
                });
            },
        },
    );
    let hatched_path = hatches.build();

    commands.spawn((
        ShapeBundle {
            path: Path(hatched_path),
            spatial: SpatialBundle {
                transform: Transform::from_translation(Vec3::new(0.0, 200.0, 1.0)),
                ..default()
            },
            ..default()
        },
        Stroke::new(Color::RED, 10.0),
    ));
}

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_plugins(ShapePlugin)
        .add_systems(Startup, setup)
        .run();
}

But the line doesn't render at all.