Bevy Image Export

A Bevy plugin for rendering image sequences.

Compatibility

Usage

const WIDTH: u32 = 768;
const HEIGHT: u32 = 768;

fn main() {
    let export_plugin = ImageExportPlugin::default();
    let export_threads = export_plugin.threads.clone();

    App::new()
        .add_plugins((
            DefaultPlugins.set(WindowPlugin {
                primary_window: Some(Window {
                    resolution: (WIDTH as f32, HEIGHT as f32).into(),
                    ..default()
                }),
                ..default()
            }),
            export_plugin,
        ))
        .add_systems(Startup, setup)
        .run();

    // This line is optional but recommended.
    // It blocks the main thread until all image files have been saved successfully.
    export_threads.finish();
}

fn setup(
    mut commands: Commands,
    mut images: ResMut<Assets<Image>>,
    mut export_sources: ResMut<Assets<ImageExportSource>>,
) {
    // Create an output texture.
    let output_texture_handle = {
        let size = Extent3d {
            width: WIDTH,
            height: HEIGHT,
            ..default()
        };
        let mut export_texture = Image {
            texture_descriptor: TextureDescriptor {
                label: None,
                size,
                dimension: TextureDimension::D2,
                format: TextureFormat::Rgba8UnormSrgb,
                mip_level_count: 1,
                sample_count: 1,
                usage: TextureUsages::COPY_DST
                    | TextureUsages::COPY_SRC
                    | TextureUsages::RENDER_ATTACHMENT,
                view_formats: &[],
            },
            ..default()
        };
        export_texture.resize(size);

        images.add(export_texture)
    };

    commands
        .spawn(Camera3dBundle {
            transform: Transform::from_translation(5.0 * Vec3::Z),
            ..default()
        })
        .with_children(|parent| {
            parent.spawn(Camera3dBundle {
                camera: Camera {
                    // Connect the output texture to a camera as a RenderTarget.
                    target: RenderTarget::Image(output_texture_handle.clone()),
                    ..default()
                },
                ..default()
            });
        });

    // Spawn the ImageExportBundle to initiate the export of the output texture.
    commands.spawn(ImageExportBundle {
        source: export_sources.add(output_texture_handle),
        settings: ImageExportSettings {
            // Frames will be saved to "./out/[#####].png".
            output_dir: "out".into(),
            // Choose "exr" for HDR renders.
            extension: "png".into(),
        },
    });
}

Video file export

With FFmpeg installed, you can run the following command to convert your exported image sequence to an MP4 video file:

ffmpeg -r 60 -i out/%05d.png -vcodec libx264 -crf 25 -pix_fmt yuv420p out.mp4