Weird Constructor's Bevy Link and Tips Collection

WeirdConstructorsBevyLinks.md

Weird Constructor's Bevy Link and Tips Collection

• Bevy Book - Getting Started: https://bevyengine.org/learn/book/getting-started/
• Unofficial Bevy Cookbook: https://bevy-cheatbook.github.io/cookbook.html

Documentation Shortcuts

• Use time.update_with_instant for tests: https://docs.rs/bevy/latest/bevy/time/struct.Time.html#method.update_with_instant

Articles

• "Writing Tests in Bevy" by jroddev: https://blog.jroddev.com/bevy-tests/
• "automated-testing-in-bevy" by Chad Nauseam: https://chadnauseam.com/coding/gamedev/automated-testing-in-bevy
  • His helper code for tests: https://github.com/anchpop/endless-sea/blob/3b8481f1152293907794d60e920d4cc5a7ca8f40/src/tests/helpers.rs#L69-L83

Useful Crates

• bevy_debug_lines: https://github.com/Toqozz/bevy_debug_lines
• bevy_prototype_lyon: https://github.com/Nilirad/bevy_prototype_lyon

Common Problems and Code Snippets

Blurry Sprites in 2D Games

App::new()
    // Disable further blending due to anti aliasing:
    .insert_resource(Msaa { samples: 1 })
    // Disable linear interpolation of textures and default to nearest:
    .add_plugins(DefaultPlugins.set(ImagePlugin::default_nearest()))
    // .. rest of app
    .run();

Enabling Bloom

commands.spawn((
    Camera2dBundle {
        camera: Camera {
            hdr: true,
            ..default()
        },
        ..default()
    },
    BloomSettings {
        threshold: 0.0,
        intensity: 5.0,
        ..default()
    }
));

Write/Draw into Image/Texture

fn setup_sprite_thing(
    mut commands: Commands,
    mut textures: ResMut<Assets<Image>>,
    mut materials: ResMut<Assets<ColorMaterial>>,
) {
    use bevy::render::render_resource::{Extent3d, TextureDimension, TextureFormat};

    let (width, height) = (256, 256);
    let mut bytes = Vec::with_capacity(width * height * 4);
    for _y in 0..height {
        for _x in 0..width {
            bytes.push(0xff);
            bytes.push(0x00);
            bytes.push(0x00);
            bytes.push(0xff);
        }
    }

    let texture = Image::new(
        Extent3d{
            width: width as u32,
            height: height as u32,
            depth_or_array_layers: 1,
        },
        TextureDimension::D2,
        bytes,
        // See also wgpu code in Bevy, and font texture creation
        TextureFormat::Rgba8UnormSrgb,
    );

    let texture_handle = textures.add(texture);

    commands.spawn(Camera2dBundle::default());
    commands.spawn(SpriteBundle {
        texture: texture_handle,
        ..Default::default()
    });
}

Modify Colors of an TextureAtlas before loading

            let image = image_handle.clone();
            let mut image_dynamic = image.try_into_dynamic().unwrap();
            image_dynamic = image_dynamic.huerotate(rand.gen_range(0..360));
            // .brighten(-50);

            let texture_handle = assets.add(Image::from_dynamic(image_dynamic, true));
            let texture_atlas =
                TextureAtlas::from_grid(texture_handle, Vec2::new(122.0, 122.0), 34, 1, None, None);
            let texture_atlas_handle = texture_atlases.add(texture_atlas);