bullshit.rs

struct World;
struct UI;

struct VulkanoRenderer;
struct GFXRenderer;

impl Renderer<World> for VulkanoRenderer{/*...*/}
impl Renderer<UI> for VulkanoRenderer{/*...*/}

impl Renderer<World> for GFXRenderer{/*...*/}
impl Renderer<UI> for GFXRenderer{/*...*/}

trait Renderer<T> {
  fn render_item(&mut self, _: &mut T);
}