Bevy Gpu Insert

Insert data from buffers on the Gpu to the MainWorld.

Take a look at the example: cargo r --example gpu-generate.

The example computes the mesh on the Gpu and inserts it to the MainWorld. For simplicity the inserted mesh is extracted and prepared even though the data already persists on the Gpu.

impl GpuInsert for GeneratedMesh {
    type Info = Handle<GeneratedMesh>;
    type Param = SResMut<Assets<GeneratedMesh>>;

    fn insert(
        data: &[u8],
        info: Self::Info,
        assets: &mut SystemParamItem<Self::Param>,
    ) -> Result<(), GpuInsertError> {
        let mut mesh = Mesh::new(PrimitiveTopology::TriangleList);

        let data: Vec<_> = data
            .chunks_exact(4)
            .map(|b| f32::from_ne_bytes(b.try_into().unwrap()))
            .collect();

        ...

        let _ = assets.set(info, Self(mesh));

        Ok(())
    }
}

fn queue_gpu_inserts(
    mut gpu_insert_commands: ResMut<Vec<GpuInsertCommand<GeneratedMesh>>>,
) {
    gpu_insert_commands.push(GpuInsertCommand {
        buffer,
        bounds: 0..size,
        staging_buffer,
        staging_buffer_offset: 0,
        info: handle.clone_weak(),
    });
}

app.add_plugin(GpuInsertPlugin::<GeneratedMesh>::default());

let render_app = app.sub_app_mut(RenderApp);

...

let mut render_graph = render_app.world.resource_mut::<RenderGraph>();

render_graph.add_node(
    compute::graph::node::GENERATE_MESH,
    GenerateMeshNode::default(),
);

render_graph.add_node(
    compute::graph::node::STAGE_GENERATED_MESH, StagingNode::<GeneratedMesh>::default()
);

render_graph
    .add_node_edge(
        compute::graph::node::GENERATE_MESH,
        compute::graph::node::STAGE_GENERATED_MESH,
    )
    .unwrap();

render_graph
    .add_node_edge(
        compute::graph::node::STAGE_GENERATED_MESH,
        bevy::render::main_graph::node::CAMERA_DRIVER,
    )
    .unwrap();