# bevy_headless_render

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A plugin for the [Bevy](https://bevyengine.org) engine which allows for headless rendering.

Every frame will be copied from `HeadlessRenderSource` render textures into `HeadlessRenderDestination` images each frame.

## Compatibility

| Crate Version | Bevy Version |
|---            |---           |
| 0.1           | 0.14         |

## Installation

### crates.io
```toml
[dependencies]
bevy_headless_render = "0.1"
```

### Using git URL in Cargo.toml
```toml
[dependencies.bevy_headless_render]
git = "https://github.com/exvacuum/bevy_headless_render.git"
```

## Usage

In `main.rs`:
```rs
use bevy::prelude::*;
use bevy_headless_render;

fn main() {
    App::new()
        .add_plugins((
            DefaultPlugins
            .build()
            .disable::<WinitPlugin>(),
            ScheduleRunnerPlugin::run_loop(Duration::from_secs_f32(1.0 / TICK_RATE)),
            bevy_headless_render::HeadlessRenderPlugin,
        ))
        .run();
}
```

When spawning a camera:
```rs
let size = Extent3d {
    width: 640,
    height: 480,
    depth_or_array_layers: 1,
};

let mut image = Image {
    texture_descriptor: TextureDescriptor {
        label: None,
        size,
        dimension: TextureDimension::D2,
        format: TextureFormat::R8Unorm,
        mip_level_count: 1,
        sample_count: 1,
        usage: TextureUsages::TEXTURE_BINDING
            | TextureUsages::COPY_SRC
            | TextureUsages::RENDER_ATTACHMENT,
        view_formats: &[],
    },
    ..default()
};

image.resize(size);

let image_handle = images.add(image); // ResMut<Assets<Image>>

commands.spawn((
    Camera3dBundle {
        camera: Camera {
            target: image_handle.clone().into();
            ..Default::default()
        },
        ..Default::default()
    },
    bevy_headless_render::HeadlessRenderBundle {
        source: headless_render_sources.add(HeadlessRenderSource(image_handle.clone())), // ResMut<Assets<HeadlessRenderSource>>
        destination: HeadlessRenderDestination::default(),
    },
));
```

The HeadlessRenderDestination component will contain the extracted image which can be used or saved for whatever you need.

## License

This crate is licensed under your choice of 0BSD, Apache-2.0, or MIT license.