Bevy - Render to wgpu::Texture

Question

I am looking for an elegant and hopefully bevy-esque way of rendering to a wgpu::Texture. The reason is that I'm am implementing a WebXR libary and the WebXRFramebuffer must be rendered to in immersive XR.

let framebuffer = //get framebuffer from web_sys
let texture: wgpu::Texture = unsafe {
        device.create_texture_from_hal::<wgpu_hal::gles::Api>(
            wgpu_hal::gles::Texture {
                inner: wgpu_hal::gles::TextureInner::ExternalFramebuffer {
                    inner: framebuffer,
...

My question is, once I have created this wgpu::Texture is there a way to either:

1. Set it as the main pass texture of the bevy engine
2. Render the cameras to a bevy::Image and blit that to the wgpu::texture

I've seen examples like the superconductor engine doing a lot of low level wgpu work to achieve this but it feels like there should be a simpler way with recent bevy features like the render graph and camera render targets.

Answer 1

Rendering to a TextureView is supported as of Bevy 0.11, see the pr for more info.

here's an exerpt from my web_xr crate that sets the TextureView from a gl_layer as a target that cameras can render to. Look here for creating the camera and here for applying the texture view.

/// set the texture view in camera
...
let mut entity = commands.spawn(Camera3dBundle {
            camera_3d: Camera3d {
                clear_color, //split screen
                ..default()
            },
            camera: Camera {
                order,
                target: RenderTarget::TextureView(**texture_id),
                viewport: Some(xr_camera.viewport.clone()),
                ..default()
            },
            transform: pose.into(),
            ..default()
        });
}

/// updating the texture view
pub fn update_manual_texture_views(
    gl_layer: NonSend<web_sys::XrWebGlLayer>,
    render_device: Res<RenderDevice>,
    texture_id: Res<bevy_utils::FramebufferTextureViewId>,
    mut manual_tex_view: ResMut<ManualTextureViews>,
) {
    let dest_texture = xr_utils::create_framebuffer_texture(
        render_device.wgpu_device(),
        &gl_layer,
    );

    let size =
        UVec2::new(gl_layer.framebuffer_width(), gl_layer.framebuffer_height());

    let descriptor = wgpu::TextureViewDescriptor::default();
    let view = dest_texture.create_view(&descriptor);

    manual_tex_view.insert(
        **texture_id,
        ManualTextureView::with_default_format(view.into(), size),
    );
}