bevy_debug_lines

A plugin providing a simple line drawing api for bevy.

Click on the above demo to play it.

Master branch has no stability guarantees.

About

This plugin uses a shader and sends individual points to the GPU, which then moves geometry to make a line. This is quite fast with a significant number of lines, and there is no added cost to moving lines around.

Usage

Add bevy_prototype_debug_lines to your Cargo.toml:

[dependencies]
bevy_prototype_debug_lines = "0.8"
# Or, for 3d:
# bevy_prototype_debug_lines = { version = "0.8", features = ["3d"] }

Add the plugin in your App::new() phase:

use bevy::prelude::*;
use bevy_prototype_debug_lines::*;

fn main() {
    App::new()
        .add_plugins(DefaultPlugins)
        .add_plugin(DebugLinesPlugin::default())
//      ...
        .run();
}

Draw a line in whatever system you have using the DebugLines resource:

fn some_system(
//  ...
    mut lines: ResMut<DebugLines>,
) {
    let start = Vec3::splat(-1.0);
    let end = Vec3::splat(1.0);
    let duration = 0.0;     // Duration of 0 will show the line for 1 frame.
    lines.line(start, end, duration);
}

Depth testing (drawing lines through geometry instead of always on top) can be changed using the DebugLinesPlugin::with_depth_test() method:

use bevy::prelude::*;
use bevy_prototype_debug_lines::*;

fn main() {
    App::new()
    .add_plugins(DefaultPlugins)
    .add_plugin(DebugLinesPlugin::with_depth_test(true))
//  ...
    .run();
}

See the examples for more complete usage examples.

Troubleshooting

Lines do not show up

Problem: Lines do not show up on screen, even if I added the DebugLinesPlugin and used DebugLines::lines

Solution: Check the dimension feature of bevy_debug_lines, when running your game, there should be a log message looking like:

INFO bevy_prototype_debug_lines: Loaded 2d debug lines plugin.

Pay attention to Loaded 2d debug this should match what you are using in your game. Is it a 3d game? If so, you should add the bevy_prototype_debug_lines/3d feature flag to your Cargo.toml. It should look like this:

bevy_prototype_debug_lines = { version = "0.8", features = ["3d"] }

Running Examples

You can run the examples like so:

cargo run --example 3d --features="example_deps"

Where 3d is one of the files in the examples

Changes in 0.3.0

In 0.3.0, the thickness parameter has been removed. I don't believe it provides enough value for the performance, time, or issues. However, if you feel differently, let me know in this issue.

This is technically a non-breaking change (i.e. your code will still compile) because duration was added which takes the same spot, but beware that your code still needs to be updated (probably just set old thickness values to 0, if you don't care about duration stuff.).

Changes in 0.6.0

• Support Bevy 0.6.
• Use a .wgsl shader, which should improve web compatibility.
• The DebugLines.depth_check field has been removed in favor of DebugLinesPlugin::with_depth_test() -- see depth_test example.
• When adding the plugin, we now need to use DebugLinesPlugin::default() instead of just DebugLinesPlugin.
• Due to underlying changes in the bevy renderer, 3d and 2d have been split into separate features. If you are using bevy_debug_lines in a 3d game, add the features = ["3d"] line to your bevy_prototype_debug_lines dependency. Sorry!

Bevy Version Support

bevy	bevy_prototype_debug_lines
0.8	0.8
0.7	0.7
0.6	0.6
0.5	0.3
0.4	0.2.1

---

Please do not hesitate to let me know if you have any requests, improvements, or suggestions on how to make this crate more ergonomic or otherwise.